JPH11303874A - Rolling member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive rolling device improved in fretting resistance, acoustic performance, corrosion resistance, service life and workability. SOLUTION: In a rolling device composed of an outer member, an inner member and a plurality of rollers interposed between the former two members, in which the rollers roll on a first contract surface that is the surface of the outer member making contact with the rollers, and on a second contact surface that is the surface of the inner member making contact with the rollers, at least one of the outer member, the inner member and rollers is made of a steel alloy containing <=1.5 wt.% of C, >=10 wt.% and <=20 wt.% of Cr, >=0.1 wt.% and <=0.8 wt.% of Mn, >=0.1 wt.% and <=1.0 wt.% of Si, and <0.2 wt.% of N.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing, a linear guide bearing, and the like used in precision equipment such as an HDD (hard disk drive) and a VTR, a food machine, an aircraft, a machine tool, a semiconductor-related equipment, and the like. The present invention relates to a rolling device such as a ball screw device, which has excellent characteristics such as fretting resistance, acoustic performance, corrosion resistance and workability by improving the material composition.

[0002]

2. Description of the Related Art Generally, as a material for a rolling bearing, SUJ2 is used for bearing steel, and SUS is used for stainless steel.
440C or 13Cr martensitic stainless steel, or SCR420 or SCM4 for case hardened steel
20 steel materials are used. Rolling bearings are repeatedly subjected to shear stress under high surface pressure and used to withstand the shear stress and secure the rolling fatigue life. Tempering, and case hardening steel are quenched and tempered after carburizing or carbonitriding to achieve a hardness of HRC 58 to 64.

[0003] However, the use environment of these rolling bearings is various, and the use of bearing steel is not sufficient because of salt damage in an area adjacent to the sea, intrusion of water or seawater, or in a wet or other corrosive environment. Exposure or use may cause premature rusting.

Therefore, a rolling bearing which is used in a corrosive environment and in which it is particularly necessary to avoid rusting is excellent in corrosion resistance and hardness HR required for the bearing.
High carbon Cr as stainless steel bearing steel having C58 or more
Martensitic SUS440C and the like have been conventionally used.

[0005] Rolling bearings used for transporting various types of spindles or various types of spindle motors and for use in swing arms of HDDs and the like have excellent rotation and excellent rotation.
It is required to have acoustic performance and fretting resistance and small torque fluctuation. However, the conventional stainless steel contains a large number of coarse eutectic carbides exceeding 10 μm, so that it is difficult to obtain the target processing accuracy. For example, the acoustic performance tends to be inferior to that of bearing steel. is there.

For this reason, rolling bearings made of bearing steel are often used for spindle motors, which are used particularly for rotationally driving magnetic disks and require rotational and acoustic performance, for the reasons described above. On the other hand, the rolling bearing for the swing arm, which is used to drive the swing arm for positioning the access to the effective area of the magnetic disk, is used under the oscillating condition. An oil film is not easily formed on the HDD, and torque fluctuations and torque spikes may occur due to fretting wear, which may cause a failure in the reading function of the HDD device.

Therefore, high-carbon Cr stainless steel having good fretting resistance is often used for a rolling bearing for a swing arm, and in recent years, a 13Cr-based martensitic system with improved rotational and acoustic performance has been used. Stainless steel is often used as a stainless bearing steel for a rolling bearing used in a swing arm of an HDD device or the like.

On the other hand, in the case of a linear motion guide bearing device comprising a guide rail and a slider or a ball screw device comprising a screw shaft and a nut, JIS-SUS440C or 1 is used as a corrosion-resistant stainless steel material used for these.
A 3Cr martensitic stainless steel (carbon content: 0.6 to 0.7%) and a precipitation hardening stainless steel such as JIS-SUS630 are used.

[0009]

SUMMARY OF THE INVENTION In the case of a rolling bearing In the high carbon Cr stainless steel as described above, C,
When the content of Cr is large, for example, when C is contained in excess of 0.6% by weight, a large number of coarse eutectic carbides exceeding 10 μm are formed in combination with a large amount of Cr, and these are used as rolling elements. There is a problem that not only the fatigue life, toughness, corrosion resistance and the like are reduced, but also the workability such as forgeability and machinability is deteriorated.

[0010] Furthermore, the presence of coarse eutectic carbides can also adversely affect the acoustic performance of the bearing. Acoustic performance refers to the low noise generated by signals generated while the bearing is operating.For relatively small stainless steel rolling bearings used in precision equipment that extremely dislikes vibration such as HDD devices, Often a big problem.

That is, the vibration generated in the bearing is
It largely depends on the accuracy of the shape of the outer ring, inner ring or shaft body, and rolling element. Therefore, when a material having coarse eutectic carbides is used for the bearing, the coarse carbides become a hindrance to the achievement of the target accuracy when finishing the bearing, and further during rotation operation. Also, a difference in wear occurs between the matrix and the eutectic carbide, which causes a reduction in accuracy such as roughness, and further, these carbides interfere with each other on the contact surface, resulting in an increase in noise.

As described above, the coarse eutectic carbide not only reduces the acoustic performance of the bearing, but also reduces the fatigue life as a stress concentration source, and further causes deterioration in toughness, corrosion resistance, and the like.

Therefore, high carbon C such as SUS440C
r Martensitic stainless steel not only does not have sufficient corrosion resistance and mechanical strength as stainless steel, but also has extremely poor acoustic performance and high cost, so bearings and various spindles used in a corrosive environment, or Rolling bearings used in various types of spindle motors, swing arms for HDD devices, and the like cannot be suitably used.

In addition, these rolling bearings are often fixed with an adhesive, and if rust-preventive oil is attached, the adhesive strength is reduced, or the rust-preventive oil chemically reacts with this to cause rust. In addition, there are various problems such as the occurrence of outgassing and the generation of outgas which adheres to the disk surface and lowers the reliability of the HDD device. Therefore, the bearing is often completely degreased. Is preferred. However, stainless steel is not only higher in cost than bearing steel such as SUJ2, but also has better corrosion resistance and fretting resistance than SUJ2, but has a large number of coarse eutectic carbides. It is difficult to obtain processing accuracy. Also, since the acoustic performance of the bearing tends to be inferior to that of SUJ2, it has been difficult to use it for a rolling bearing for a spindle motor that requires high rotational and acoustic performance. Further, with respect to rolling bearings for various types of spindles, further improvements are required in the fretting resistance during transportation and operation of the spindles.

Japanese Patent Publication No. 5-27334 discloses that C, Cr
Discloses a rolling bearing made of martensitic stainless steel in which the formation of a eutectic carbide is suppressed by reducing the content of, and the acoustic performance, fatigue strength and the like are remarkably improved. However, this is inferior to SUJ2 in terms of the size of the carbide, so that not only is the acoustic performance inferior, but also no consideration is given to the cost. Further, this publication discloses the required characteristics of a rolling bearing for an HDD swing arm. No matters concerning fretting resistance are specified, and no description is made on workability.

Further, Japanese Unexamined Patent Publication (Kokai) No. 6-117439 discloses that one or both of the inner ring and the outer ring are made of martensitic stainless steel and the rolling elements are made of bearing steel to reduce the cost and to improve the acoustic performance. Attempts have been made to improve the acoustic performance because the stainless steel used for the bearing ring is the same as the martensitic stainless steel described in Japanese Patent Publication No. 5-2734. It was inferior to bearing steels such as SUJ2, and was inferior in terms of acoustic performance to rolling bearings made of bearing steel in all of the inner ring, outer ring and rolling elements. Also, as in Japanese Patent Publication No. 5-2734, this publication does not clearly disclose matters relating to fretting resistance, which is a required characteristic of a rolling bearing for an HDD swing arm, and does not make any description regarding workability.

Also, in both of the above prior arts, when corrosion resistance is particularly required, it cannot be said that measures are necessarily sufficient.

In the case of a linear motion guide bearing device and a ball screw device, such as a linear guide device, when a component to be used has a complicated irregular cross-sectional shape like a slider or a rail,
Since the material is often subjected to cold deformed drawing to a shape as close as possible to the shape of the finished product, stainless steel, which is difficult to process, has large deformation resistance and work hardening. For this reason, it takes a lot of time and cost to draw out deformed shapes, and case hardening steel such as SCM420 and SCR420 and S45C, which have relatively good workability.
There is a problem that the cost is remarkably higher than that of carbon steel for machine structure such as S53C and S53C.

In particular, precipitation-hardening stainless steel such as SUS630 has very high corrosion resistance, but has a hardness of about 33 to 36 HRC even in a solution-treated state, so that it has extremely poor cold workability and component manufacturing costs. At present, the cost is very high and it is rarely used except for special fields such as nuclear power.

Therefore, in recent years, SUS4 which is difficult to process is used.
The use of 13Cr-based high carbon martensitic stainless steel, which has a reduced carbon and Cr content of 40C and improved cold deformability, has been used. But,
Even with this material, the improvement effect is still insufficient, and the problems such as the lack of the mold at the early stage and the necessity of reworking have not been sufficiently solved.

Further, in the conventional high-carbon martensitic stainless steel, when a deformed shape is drawn, work hardening occurs and a longitudinal aging crack may occur along the groove having the largest area reduction. Special attention should be paid to tempering immediately.

Further, since the linear motion guide device having the above-mentioned rolling element is often used under repeated high shear stress under high surface pressure like a rolling bearing, the linear motion guide device is required to withstand the shear stress and secure the rolling fatigue life. In manufacturing, quenching treatment is performed after molding to increase the surface hardness. As a conventional quenching method, a method of performing soaking quenching in a vacuum and a method of performing induction quenching are well known, but in the former, since the entire part is quenched after being heated to a high temperature, the part shape is irregular or long. The smaller the length, the more unbalanced the cooling rate of the entire part may be, resulting in large deformation, bending, and twisting.

On the other hand, in the latter method of performing induction hardening, partial hardening can be easily performed by designing a hardening coil, and it is not necessary to apply heat to the entire part. There is an advantage that the deformation, bending, twisting, etc. of the non-cured layer can be reduced, and the non-hardened layer such as the core is sufficiently soft, so that the deformation can be easily corrected. For this reason, among the parts such as rails and sliders that constitute the linear guide device, particularly in the case of irregular or long parts, the quenching is more often performed by the latter induction hardening.

However, in the conventional stainless steel, the diffusion rate of carbon is lower than that of carbon steel for mechanical structure, and the coarse eutectic carbide generated in the solidification process is hard to melt into the matrix. , It is difficult to obtain a hardened hardened layer depth by heating for a short time. Also, when trying to obtain a deep hardened layer depth by high frequency output, quenching speed, etc., the Ms point decreases due to excessive penetration of carbides, martensitic transformation is suppressed, and a large amount of untransformed austenite remains, resulting in surface hardening. There were also problems such as being unable to be performed and unevenness in hardness. Also,
Conventional stainless steel contains a large number of coarse eutectic carbides regardless of the quenching method, which acts as a source of stress concentration, reduces rolling fatigue life, and does not have sufficient corrosion resistance. There were also problems.

JP-A-2-310342 and JP-A 3-1342
Japanese Patent No. 38335 discloses a martensitic stainless steel for cold forging and a method for producing the same. However, these stainless steels not only lack the content of carbon that contributes to solid solution or precipitation strengthening, Since it does not contain nitrogen which has a favorable effect on dynamic fatigue life, wear resistance, corrosion resistance, etc., it is not sufficient for bearing applications which are repeatedly subjected to fatigue under high surface pressure.

Since the linear guide device and the ball screw device are repeatedly reciprocated in a short stroke, fretting resistance is required as in the case of a rolling bearing.

Used under particularly severe conditions such as corrosion resistance
Case (rolling bearings, linear guide bearings, ball bearings)
Problems common to all threading devices) If the above rolling devices such as rolling bearings, linear motion guide bearing devices, and ball screw devices require particularly corrosion resistance, these stainless steels and bearing steels, and carburized or carbonitrided A case hardened steel treated with hard Cr plating, fluoridated fluoride and other various surface coatings is used. However, there is a problem that a rolling bearing suffers damages such as fatigue and wear in the vicinity of its surface, and such a coating that is discontinuous with a matrix phase falls off immediately, resulting in insufficient durability.

On the other hand, German Patent No. 3901470 discloses that an unusually high corrosion resistance and high performance martensitic stainless steel is obtained by replacing carbon with nitrogen. Stainless steels have been actively published in recent years, mainly in Europe (Pr
oceeding of International Congress Stainless Stee
l'96 (p42-p46) etc.) (Material name Cronidur 30 or X30 etc.).

In general, nitrogen addition to stainless steel is mainly performed in austenitic stainless steel. In martensitic stainless steel, the solubility of nitrogen is small, and when a large amount of nitrogen is contained, solidification occurs. There is also a problem that air bubbles are generated in the process and a large amount of pores are introduced into the ingot, thereby deteriorating the soundness of the material. Until now, research has been inactive and almost no practical use has been achieved.

On the other hand, the above-mentioned German patent enables the alloying of nitrogen exceeding 0.3% by performing steelmaking in a pressure vessel in a nitrogen atmosphere of several tens of atmospheres. However, in other words, it is necessary to perform steelmaking in a pressure vessel, and since the steelmaking process is special, there has been a problem that an increase in cost is unavoidable in terms of capital investment and productivity.

Further, the material used for corrosion-resistant bearings for aircraft or used at relatively high temperatures needs to be excellent not only in corrosion resistance but also in high-temperature life and the like. There was still room for improvement.

An object of the present invention is to provide a rolling device that solves the above-mentioned problems.

Another object of the present invention is to improve the material composition so as to impart better workability to the material composition having excellent corrosion resistance, and to improve the functions such as rolling life, fretting resistance and acoustic performance. Rolling bearings that are suitable for use in bearings used in corrosive environments, HDDs, and the like in which the rolling bearings are bonded to the shafts with an adhesive during the assembly process (thus, those that require corrosion resistance). In particular, it is to provide a ball bearing at low cost.

Still another object of the present invention is to provide not only excellent rolling life but also excellent fretting resistance and remarkably excellent corrosion resistance, which can be used in a corrosive environment or at a high temperature, and which is excellent in workability and can be provided at low cost. It is to provide a bearing device such as a linear guide device and a ball screw.

Still another object of the present invention is a case in which it is relatively unnecessary to consider corrosion resistance. By optimizing the combination of components, functions such as rolling life, fretting resistance, and acoustic performance are improved. Another object of the present invention is to provide a low-cost rolling bearing, particularly a ball bearing.

Still another object of the present invention is to provide a rolling bearing suitable for use in an environment having particularly severe corrosion resistance.
A rolling member such as a linear guide and a ball screw is provided.

[0037]

Means for Solving the Problems The present inventors consisted of an outer member, an inner member, and a plurality of rolling members disposed therebetween, wherein the rolling members contact the outer member with the rolling members. A rolling device that rolls on a first contact surface that is a surface and a second contact surface that is a contact surface of an inner member facing the rolling element with the outer member; And at least one of the rolling elements is, by weight%, C: 1.5% or less, Cr: 10% to 20%, Mn: 0.1% to 0.8%, Si;
It has been found that the above-mentioned object can be achieved by a rolling device made of an alloy steel containing 1% or more and 1.0% or less and N; less than 0.2%.

In particular, in the rolling device of the present invention, at least one of the outer member, the inner member, and the rolling member is appropriately selected from the following (1) to (6) according to a more detailed purpose or the like. It is characterized by being composed of a kind of material.

First, the following (1) to (3) are particularly low cost, excellent in corrosion resistance, and further excellent in acoustic characteristics, fretting resistance, or workability.

(1) By weight%, C: 0.6% or less, C
r: 10% to 14%, Mn: 0.1% to 0.8
% Or less, Si: 0.1% or more and 1.0% or less, N: 0.2
%; Mo; 0.5% or less; V; 0.2% or less; the balance containing Fe and unavoidable components; and the relationship between carbon and Cr content is C% ≦ −0.05Cr% + 1.41 and ,
A predetermined relational expression eq1 indicating the content of the element that promotes the ferrite formation of the material and a predetermined relational expression eq2 indicating the content of the element that promotes the austenitization of the material,
The following equation (eq1) = Cr% + Si% + 1.5Mo% + 3.5
V%, (eq2) = C% + 0.83N% + 0.12Mn%
And the correlation between the two equations and the total content of carbon and nitrogen are as follows: (eq2) ≧ 0.04 × (eq1) −0.39 eq1 ≦ 14.0, eq2 ≦ 0.8 C + N ≧ 0.45% Satisfactory martensitic stainless steel (Steel I of the present invention).

(2) Steel having hardness HRC 57 or more and secondary hardening ability, and having a nitrided layer of 2% or less of the rolling element diameter Da on the surface layer of the finished product (Steel II of the present invention).

(3) C in weight%; 0.30 to 0.45
%, Cr: 10.5-13.5%, Mn: 0.1-0.
8%, Si: 0.1 to 1.0%, N: 0.05 to 0.1
9%, C + N: 0.5% or more, the balance containing Fe and unavoidable components, martensitic stainless steel excellent in silence and corrosion resistance (invention steel III).

The above (1), (3) or high Cr
(4) is a material of a member that is effective in fretting resistance or acoustic characteristics when used in combination with a rolling member made of martensitic stainless steel.

(4) C by weight%; 0.8% or more and 1.5%
Cr: 0.1% or more and 2.0% or less, Mn: 0.1 or less
% Or more and 1.5% or less, Si; 0.1% or more and 1.0% or less, a specific high carbon steel containing the balance Fe and unavoidable components.

Next, there are the following (5) and (6) as materials for the rolling members which are required to have particularly severe corrosion resistance and the like.

(5) C in weight%; 0.45% or less, C
r: 15% to 20%, Mn: 0.1% to 0.8
%; Si; 0.1% to 1.0%; N: 0.0
5% or more and less than 0.2%, Mo; 0.5% or more and 3.0% or less, Ni; 1.5% or less, Cu; 2.0% or less, and the balance containing Fe and unavoidable components; And a predetermined relational expression eq1 indicating that the relationship between Cr and C content is C% ≦ −0.05Cr% + 1.41 and the content of the element that promotes the ferrite formation of the material, and the content of the element that promotes the austenitization of the material. The following equation (eq1) = Cr% + Si% + 1.5Mo% (eq2) = C% + 0.83N% + 0.12Mn% + 0.
05Ni% + 0.02Cu%, and the correlation between the two equations and the total content of carbon and nitrogen are as follows: (eq2) ≧ 0.04 × (eq1) −0.39, C + N ≧
0.4%, and the pitting resistance index PI value = Cr% + 3.3Mo% +
Martensitic stainless steel in which 30N% -45C% satisfies 10.0 or more (Steel IV of the present invention).

(6) C: 0.45% or less by weight%, Cr:
15% or more and 20% or less, Mn; 0.1% or more and 0.8% or less,
Si: 0.1% or more and 1.0% or less, N: 0.05% or more and 0.2%
Mo: 0.5% or more and 3.0% or less, and Ni: 1.5
%; Cu; 2.0% or less; Co; 1.0% or more and 7.0% or less; V; 1.0% or less; and the balance Fe and unavoidable components; Mo + V; 0.8% or more; 0% or less, Co + Ni; 2.
0% or more and 8.0% or less, the relationship between C and Cr content is C% ≦ −
The relational expression eq1 indicating the content of 0.055 Cr + 1.41 and the element promoting the ferrite formation of the material and the relational expression eq2 indicating the content of the element promoting the austenitization of the material are respectively expressed as follows: [eq1] = Cr% + Si % + 1.5Mo% + 3.5V%, [eq2] = C% + 0.83N% + 0.12Mn% + 0.05 (Ni + Co)% + 0.0
2Cu%, the relationship between the two and the layer content of C and N is [eq2] ≧ 0.04 × [eq1] −0.39, [eq
2] ≦ 0.8, C + N ≧ 0.4%, and PI value of pitting corrosion resistance index = Cr% + 3.3Mo% + 30N% −45C% is 1
Martensitic stainless steel satisfying 0.0 or more (Steel V of the present invention) Further, preferred embodiments of the present invention include the following embodiments.

(B) In a rolling bearing comprising an outer ring, an inner ring or a shaft, and a plurality of rolling members including a plurality of rolling elements between the outer ring and the inner ring or the shaft, at least one of the rolling members is A rolling bearing made of the above stainless steel (1).

(B) The rolling bearing according to (a), wherein the rolling elements are made of high carbon Cr martensitic stainless steel.

(C) In a rolling bearing comprising an outer ring, an inner ring or a shaft, and a plurality of rolling members including a plurality of rolling elements between the outer ring and the inner ring or the shaft, the outer ring, the inner ring or the shaft is A rolling bearing made of the specific high carbon steel (4), and a rolling element made of high Cr martensitic stainless steel.

(D) The rolling element is N: 0.05% by weight or more and 0.2%
The rolling bearing according to the above (c), which is made of a high Cr martensitic stainless steel containing less than 10% by weight.

(E) In a rolling bearing comprising an outer ring, an inner ring or a shaft, and a plurality of rolling members including a plurality of rolling members between the outer ring and the inner ring or the shaft, the outer ring, the inner ring or the shaft , By weight%, C: 0.45% or less, Cr: 12.0
% To 13.5% or less, Mn: 0.1% to 0.8% or less, S
i: from 0.1% to 1.0%, N: 0.05% to 0.5%, C + N ≧ 0.5%, Mo: 3.0% or less from the above secondary hardened steel (2) A rolling bearing in which fine carbide having a particle size of 2.0 μm or less is dispersed in the nitrided layer.

(F) The rolling bearing of (e), wherein the rolling element is made of ceramics.

(G) In a rolling bearing including an outer ring, an inner ring or a shaft, and a plurality of rolling members including a plurality of rolling elements between the outer ring and the inner ring or the shaft, at least one of the rolling members is Particle size of carbide is 2.0 μm or less, area ratio is 5
% Or less of the above stainless steel (3).

(H) When the stainless steel (3) is O ≦ 2
0 ppm, Ti + 0.1 Al ≦ 50 ppm and S ≦ 100
The rolling bearing according to the above (g), which satisfies at least one of ppm.

(I) A rolling bearing in which at least one of the outer ring, the inner ring and the shaft is made of the above stainless steel (3), and the rolling elements are made of the specified high carbon steel (4).

(G) The material of the outer ring, the inner ring, or the shaft has a carbide particle diameter of 2.0 μm or less, an area ratio of 5% or less, and at least one of the rolling element, the outer ring, and the inner ring or the shaft. (Preferably both) 0 ≦ 20 ppm, Ti + 0.1
The rolling bearing according to (1), wherein at least one of Al ≦ 50 ppm and S ≦ 100 ppm is satisfied.

(G) A linear guide bearing device comprising a guide rail, a slider and a plurality of rolling members including a plurality of rolling members, or a plurality of rolling members including a screw shaft, a nut and a plurality of rolling members. In the ball screw device, at least one of the rolling members is made of the stainless steel (1), and particularly, in the stainless steel (1), C + N ≦ 0.
Linear guide bearing device or ball screw device which is 7% by weight.

(E) The linear guide bearing device or the ball screw device according to (1) above, wherein the rolling surface with the rolling element has a hardened layer formed by induction hardening.

(C) In a rolling device comprising an outer member, an inner member and a plurality of rolling members disposed therebetween, at least one of the outer member, the inner member and the rolling member is made of stainless steel. (5) A rolling device made of (invention steel IV).

(F) In a rolling device including an outer member, an inner member, and a plurality of rolling members disposed therebetween, at least one of the outer member, the inner member, and the rolling member is made of the stainless steel. (6) A rolling device made of (steel V of the present invention).

[0062]

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment In the Case of Rolling Bearing Firstly, the inventors of the present invention disclosed in Japanese Patent Application No. 7-271111 (Japanese Patent Application Laid-Open No. 9-287053) that C, in which coarse eutectic carbide is not formed, By finding the relationship between the Cr concentration and reducing the carbon concentration in the steel that adversely affects the corrosion resistance, instead of adding nitrogen having a solid solution strengthening action similar to carbon, (1) formation of coarse eutectic carbide Can be suppressed,
(2) Dramatic improvement in corrosion resistance by adding nitrogen;
(3) Nitrogen acts on precipitation strengthening and solid solution strengthening to improve hardness and abrasion resistance, thereby inventing a martensitic stainless steel suitable for use in bearings.

However, the present invention only improves the function of the bearing, and does not mention the workability, which is very important in terms of cost, and the fretting resistance, which is a required characteristic of the bearing for the HDD swing arm. .

The inventors of the present invention have intensively studied the effects of alloy components in order to improve productivity and develop a low-cost and high-performance stainless steel for bearings. As a result, the carbon content is reduced, and instead of adding nitrogen, coarse and hard eutectic carbides are eliminated to form fine sphere (ball) -like carbides / nitrides. By suppressing the contents of Mn, Cr, Mo, V, etc. within a certain threshold value, it is possible to suppress an increase in hardness after annealing, and to dramatically improve workability, thereby providing a highly functional and inexpensive stainless steel. A steel bearing can be provided.Furthermore, by using this material on the bearing ring side and using high carbon Cr martensitic stainless steel on the rolling element side, the fretting resistance is further improved than in the case of a single material. The present inventors have found that a rolling bearing that can be suitably used as a bearing for an HDD swing arm or the like can be provided, and have accomplished the present invention.

That is, this rolling bearing is composed of a plurality of rolling members including an outer ring, an inner ring or a shaft, and a plurality of rolling elements between the outer ring and the inner ring or the shaft. At least one is, by weight, C: 0.6% or less, Cr: 10% to 14%, Mn: 0.1% to 0.8%, Si: 0.1% to 1.0%. , N;
Less than 0.2%, Mo: 0.5% or less, V: 0.2% or less, the balance contains Fe and unavoidable components, and the relationship between carbon and Cr content is C% ≦ -0.05Cr% + 1. .4
1, and a predetermined relational expression eq1 indicating the content of the element promoting the ferrite formation of the material and a predetermined relational expression eq2 indicating the content of the element promoting the austenitization of the material, respectively, the following expression (eq1) = Cr% + Si% + 1.5Mo% + 3.5
V%, (eq2) = C% + 0.83N% + 0.12Mn%,
The correlation between the two formulas and the total content of carbon and nitrogen are as follows: (eq2) ≧ 0.04 × (eq1) −0.39, eq1 ≦ 14.0, eq2 ≦ 0.8, C + N ≧ 0.45
% Martensitic stainless steel (Steel I of the present invention).

More preferably, in a shaft body provided with an outer ring, an inner ring or a raceway, and a rolling bearing composed of a plurality of rolling elements, a rolling element other than a rolling element, that is, a rolling element, At least one of the mating members (inner ring (or shaft) and outer ring) used with rolling contact between the members is made of this martensitic stainless steel, and the rolling element is made of high carbon Cr martensitic stainless steel. It is characterized by comprising.

Second Embodiment In order to provide inexpensively various kinds of high-performance spindles, or spindle motors or rolling bearings for HDDs, the present inventors applied material cost and processing to the inner and outer rings, which have a large cost reduction effect. We examined whether the acoustic performance and fretting resistance could be improved by using high-carbon steel such as bearing steel with low cost and using different materials for the rolling elements.

As a result, by using high carbon steel for the bearing ring and using stainless steel for the rolling elements, (1) the roughness accuracy on the bearing ring side is improved as compared with the conventional stainless steel rolling bearing, and Excellent acoustic performance due to the elimination of interference between coarse carbides, etc. (2) When high carbon steel and stainless steel come into contact with each other, fretting wear of stainless steel slightly increases as compared to the case of single material contact However, it has been found that fretting is significantly suppressed on the high carbon steel side, and the fretting resistance is remarkably improved as compared with a conventional bearing steel rolling bearing.

That is, stainless steel is used for the bearing ring,
When high-carbon steel is used for the rolling elements, the effect on cost is not only small, but fretting damage is more likely to occur on the raceway side made of stainless steel than when both the raceway and rolling elements are made of a single stainless steel material. If the fretting property is a problem, especially for swing arm bearings, high carbon steel is used for the race and stainless steel is used for the rolling elements. The combination used was found to be appropriate. This is because the rolling portion of the ball slightly shifts with the mating member (the bearing ring or shaft) due to the slight sliding between the bearing ring (or shaft) and the ball due to the rapid acceleration and deceleration of the rocking motion. On the other hand, the bearing ring (or shaft) has a smaller deviation, and the bearing ring (or shaft) is disadvantageous in fretting.

Further, when nitrogen is used as a component of stainless steel, nitrogen enhances the effect of reducing the friction of the passive film and facilitates the formation of a transition film on the contacting side of the contacting layer. It has been found that fretting damage of the material can be suppressed.

When high-carbon steel is used for the race and stainless steel is used for the rolling elements, the internal friction can be reduced because the high-carbon steel is slightly harder than stainless steel. Since the specific gravity of the bearing also decreases, the starting and rotational torque of the bearing tend to decrease, so that it is suitably used as a rolling bearing for transporting various spindles or various spindle motors, and for a swing arm for an HDD device, and the like. It turns out that it can.

That is, this rolling bearing is composed of a plurality of rolling members including an outer ring, an inner ring or a shaft, and a plurality of rolling members between the outer ring and the inner ring or the shaft. At least one of the rolling members is C in weight%;
0.8% or more and 1.5% or less (preferably 0.9% or less), Cr: 0.1% or more and 2.0% or less (preferably 0.6% or less), Mn: 0.1% or more and 1% or less .5% or less, S
i; made of high carbon steel containing 0.1% or more and 1.0% or less, the balance being Fe and unavoidable components (the specific high carbon steel of the above 4), and the rolling elements are made of high Cr martensitic stainless steel;
Particularly preferably, it is made of high Cr martensitic stainless steel containing 0.05% or more and less than 0.2% of nitrogen.

According to this embodiment, the cost is reflected in the conventional rolling bearings used for transporting various spindles or various spindle motors made of a single material and for swing arms for HDD devices. The outer ring, inner ring and shaft are made of high-carbon steel, which is inexpensive and has good workability.Compared to these, stainless steel is used for the rolling element, which has a smaller volume, has a simpler shape, and does not reflect much the material cost including processing costs. By using steel, these rolling bearings can be provided at low cost, and the mutual interference of carbides is eliminated. Furthermore, by improving the hardness and roughness accuracy of the bearing ring, torque and torque fluctuation are small and excellent in acoustic performance,
Furthermore, the swing durability can be improved by the fretting reduction effect of the stainless steel on the mating material. Further, in addition to the effect of reducing the wear of the rolling elements, the linear expansion coefficient and specific gravity of the rolling elements are small, so that they can be suitably used for rolling bearings for machine tools used at high speed rotation.

The present embodiment may be applied to a linear guide device or a ball screw device. In the case of a linear guide device, the rail and slider are the high carbon steel (4), the rolling elements are high Cr martensitic stainless steel, and in the case of the ball screw device, the screw shaft and nut are the high carbon steel (4), the rolling elements Is a high Cr martensitic stainless steel.

At this time, N is set to 0.05 to 0.20 in the rolling element.
It is the same as the case of the rolling bearing that the content is more preferable if it is contained by weight%.

Third Embodiment In recent years, rolling bearings for various types of spindles or various types of spindle motors and for swing arms used in HDDs and the like have been required to have higher fretting resistance. Further improvements were needed for the near future. Therefore, the inventors of the present application have conducted intensive research,
We have developed a rolling bearing that has both excellent acoustic properties and fretting resistance.

A third embodiment of the rolling bearing according to the present invention which achieves the above object is a plurality of rolling bearings comprising an outer ring, an inner ring or a shaft, and a plurality of rolling elements between the outer ring and the inner ring or the shaft. At least one of the rolling members is made of steel having secondary hardening ability, and has a nitrided layer having a surface layer of 2% or less of the rolling element diameter Da (the steel of the present invention). II). A more preferable form of the rolling bearing includes an outer ring, an inner ring or a shaft, and a plurality of rolling members including a plurality of rolling elements between the outer ring and the inner ring or the shaft. One is made of steel having secondary hardening ability, has a surface layer having a nitrided layer of 2% or less of the rolling element diameter Da, and further has rolling elements made of a ceramic material.

In this embodiment, the surface layer has 480
C nitrided at a temperature of 430 ° C. or lower, preferably 430 ° C. or lower.
A nitride layer (nitrogen-enriched layer) made of r-nitride, Fe-nitride, etc.
have. By applying such a nitrided layer to the bearing material, adhesion can be prevented, friction can be reduced and fretting damage can be significantly improved. In this case, if the bearing material is a general bearing material such as SUJ2 which does not have the secondary hardening ability, it becomes very soft under the nitride layer after the nitriding treatment. Plastic deformation occurs, which causes deterioration of acoustic characteristics. Therefore, it is a necessary condition that the material has a secondary curing ability, and preferably has an HRC of 57 or more, more preferably has a very fine carbide having a size of 2 μm or less, and is particularly preferably. Is C; 0.4
5% or less, N: 0.05 to 0.50%, preferably N: 0.05 to 0.20%, C + N: 0.5 from the viewpoint of cost
0% or more, Cr; 12 to 13.5%, Mn; 0.1 to
0.8%, Si; 0.1 to 1.0%, Mo as required;
Martensitic stainless steel containing 3% or less, preferably 0.5% or less, with the balance being Fe and unavoidable components is used.

Rolling bearings used in information equipment are particularly strictly controlled in precision. Therefore, when the nitriding temperature is high, the surface roughness and roundness are impaired, making the rolling bearing unusable.
Therefore, the nitriding temperature is preferably 480 ° C or lower, more preferably 430 ° C or lower.

The bearing is usually processed into a desired shape by cutting, and then assembled and shipped through processes such as heat treatment, cutting, and finishing.
The nitriding treatment is performed at a higher temperature (450
480 ° C.) and then a second hardening treatment (high temperature tempering) is performed. In some cases, after quenching and secondary hardening, cutting and grinding are performed, and nitriding is performed before final finishing.

If the interface between the nitrided layer and the underlayer becomes deeper than the maximum shear stress depth, the interface or the nitrided layer may be cracked or damaged due to an impact load or excessive pressurization during transportation. The depth of the nitrided layer is set to 2% or less of the rolling element diameter Da, and the underlayer has high toughness and can withstand rolling fatigue.
57 or more secondary hardened steel. On the other hand, when the nitride layer depth is large, not only does the cost increase due to long-time treatment, but also the surface roughness and roundness tend to decrease, which may cause problems in production, which is not preferable.

In the present embodiment, since the rolling elements are made of ceramic balls, adhesion is more unlikely to occur and fretting damage tends to be reduced. Preferably, a ball is used.

Fourth Embodiment The inventors of the present application have conducted intensive studies and have developed a high-performance and inexpensive rolling bearing for information equipment by improving the material composition. A fourth embodiment of the rolling bearing according to the present invention that achieves the above object is a plurality of rolling elements including an outer ring, an inner ring or a shaft, and a plurality of rolling elements between the outer ring and the inner ring or the shaft. 9. In a stainless steel rolling bearing composed of a member, at least one of the rolling members has a weight percentage of C: 0.30 to 0.45%, and Cr;
5 to 13.5%, Mn; 0.1 to 0.8%, Si;
1 to 1.0%, N; 0.05 to 0.19%, C + N;
A rolling bearing characterized by being composed of martensitic stainless steel (steel III of the present invention) containing 0.5% or more, the balance being Fe and unavoidable components, and having excellent quietness and corrosion resistance.

Further, as a preferred form of the rolling bearing of the present embodiment, the particle size of the contained carbide is 2.0 μm or less,
One having an area ratio of 5% or less so that quietness and corrosion resistance can be more reliably obtained.

Further, as a more preferable embodiment of the rolling bearing of the present embodiment, a rolling bearing containing 20 ppm or less of O or a total of 50 ppm or less of Ti + 0.1Al, and particularly preferably containing 100 ppm of S
Rolling bearings that are less than ppm.

Fifth Embodiment The inventors of the present invention have made intensive studies and made further improvements, and have developed a low-cost rolling bearing material having excellent functions such as acoustic performance. Further, the inventors of the present application consider that the rolling element is made of the steel III of the present invention in consideration of the fact that the corrosion resistance is ensured by grease sealed in the bearing, and the rolling element is made of an inexpensive high carbon bearing. We considered the construction of steel balls. As a result, when a ball made of high-precision high-carbon bearing steel is used for the rolling element, if the orbit theory is the conventional 13Cr martensitic stainless steel,
Since hard and coarse carbides of M7C3 type and M23C6 type were present, it was found that sufficient durability could not be obtained, for example, the surface accuracy of the ball gradually deteriorated and the acoustic performance was reduced during rotation. On the other hand, when the steel V of the present invention is used for the orbital theory, the carbides and nitrides contained therein are very fine, and nitrogen enhances the friction reducing effect of the passive layer film. It was found that the precision of the moving body could be prevented from deteriorating, and that it had much better durability than conventional steel.

A fifth embodiment of the rolling bearing of the present invention which achieves the above object is a plurality of rolling elements including an outer ring, an inner ring or a shaft, and a plurality of rolling elements between the outer ring and the inner ring or the shaft. In a rolling bearing made of stainless steel constituted by the rolling members described above, at least one of the rolling members excluding the rolling elements has a C content of 0.30 to 0.45% by weight.
r: 10.5 to 13.5%, Mn: 0.1 to 0.8%,
Si: 0.1 to 1.0%, N: 0.05 to 0.19%,
C + N: made of martensitic stainless steel (Steel III of the present invention) containing 0.5% or more, the balance Fe and unavoidable components, and having excellent quietness and corrosion resistance.
A rolling bearing excellent in acoustic performance, characterized in that the rolling element is made of the specific high carbon steel of (4).

As a preferred form of the rolling bearing of the present embodiment, the particle size of the contained carbide is 2.0 μm or less,
One having an area ratio of 5% or less so that quietness and corrosion resistance can be more reliably obtained.

Further, as a more preferred form of the present embodiment, at least one (more preferably, both) of the stainless steel used for at least one of the outer ring, the inner ring and the shaft and the high carbon bearing steel used for the rolling elements.
O: 20 ppm or less, or Ti + 0.1 Al; 50 p
pm or less.

In the case of a linear motion guide bearing device and a ball screw device
(Sixth Embodiment) The inventors of the present invention reduced the carbon content and eliminated the coarse and hard eutectic carbides by adding nitrogen instead to form fine spherical carbides / nitrides. In addition, by suppressing the contents of Si, Mn, Cr, and Mo within a certain threshold value, it is possible to suppress an increase in hardness after annealing, and to dramatically reduce deformation resistance and improve cold workability. Improved and can be suitably applied to parts such as sliders and rails for linear motion guide devices having an irregular cross-sectional shape.
Since the nitride is fine and homogeneous, it is easy to obtain a hardened hard layer depth by short-time induction hardening, and it is possible to reduce variation in heat treatment quality.In addition, even if the quenching method is either vacuum quenching or induction hardening The present inventors have found that good corrosion resistance and fatigue life can be obtained as compared with conventional steels such as SUS440C and 13Cr-based high-carbon martensitic stainless steel, and have accomplished the present invention.

The linear motion guide bearing device or ball screw device which achieves the above object is constituted by a plurality of rolling members including a guide rail, a slider or a screw shaft, a nut and a plurality of rolling elements. At least one of the members is made of a martensitic stainless steel of the steel I of the present invention. In particular, the steel I of the present invention preferably satisfies C + N ≦ 0.7% by weight.

In a linear guide bearing device and a ball screw device comprising a guide rail, a slider or a screw shaft, a nut and a plurality of rolling elements, at least one of components such as a rail and a slider having an irregular cross-sectional shape. One, after annealing, consists of a mixed structure of fine carbides or nitrides and ferrite, and after cold deformed drawing to a shape close to the desired finished product shape, only the surface layer or rolling parts are high frequency It is characterized by having a quench hardened layer by quenching. Here, the surface layer means, for example, within 2% of the diameter of the rolling element.

According to this embodiment, with respect to the stainless steel material as a constituent material, carbon, which is a component that has a bad effect on corrosion resistance and forms a coarse eutectic carbide to reduce the function when the content is large, is used. By controlling the carbon concentration within a certain range by partially substituting with nitrogen having the same solid solution strengthening action, it is possible to suppress the formation of coarse eutectic carbides, and it is excellent in corrosion resistance and rolling life etc. Further, by setting the content of other alloy components in an appropriate range, the workability and the heat treatment productivity are improved, and as a result, a high-performance linear motion guide bearing device can be manufactured at low cost.

Further, since the cold workability, rolling fatigue life characteristics after heat treatment, and corrosion resistance are much better than conventional steel, pipes, coils, and steel bars for bearings that are cold-worked and manufactured regardless of deformed shapes. And the like can be easily applied.

Furthermore, the rolling device of this embodiment is excellent in fretting resistance, and can be suitably used for a ball screw or a linear guide for a table device which repeatedly reciprocates a short stroke.

Preferably, as in the first embodiment relating to the rolling bearing described above, the rolling elements are made of high carbon Cr martensitic stainless steel. For example, in a linear guide, a rail slider or a rail is formed of the present invention steel I, and a rolling element is formed of high Cr martensitic stainless steel. In a ball screw device, a nut and a screw shaft are formed of the present steel I and a rolling element is formed of high Cr martensite. It may be made of sight stainless steel.

When particularly severe corrosion resistance is required
(Including rolling bearings, linear motion guide bearing devices, and ball screw devices
In the present application we Japanese Patent Application No. 7-271111 as common) above seventh embodiment in the rolling member containing not coarse carbides are formed C, found the relationship between the Cr concentration, further soundness of material The present invention has been made to achieve low cost by adding nitrogen within a range in which is maintained, and to further enhance the function of a conventional stainless steel. The inventors of the present application have intensively studied to further improve the function. As a result, a material structure having extremely excellent corrosion resistance without generating coarse eutectic carbide and δ ferrite which are harmful to rolling fatigue life has been found.

A rolling bearing and other rolling devices for achieving the above object are a rolling device comprising an outer member, an inner member, and a plurality of rolling elements disposed therebetween, wherein the outer member, the inner member, At least one of the rolling elements has C;
5% or less, Cr: 15% or more and 20% or less, Mn: 0.1
% To 0.8%, Si: 0.1% to 1.0%, N: 0.05% to less than 0.2%, Mo: 0.5%
Not less than 3.0%, Ni: 1.5% or less, C
u: contains 2.0% or less and the balance Fe and unavoidable components, and the relationship between C and Cr content is C% ≦ −0.05Cr%
+ Eq.41, and a relational expression eq1 indicating the content of the element promoting the ferritization of the material and a relational expression eq2 indicating the content of the element promoting the austenitization of the material, respectively: (eq1) = Cr% + Si% +1.5 Mo%, (eq2) = C% + 0.83 N% + 0.12 Mn% + 0.
05Ni% + 0.02Cu%, and the correlation between the two formulas and the total content of carbon and nitrogen is (eq2) ≧ 0.04 × (eq1)
-0.39, C + N ≧ 0.4%, and the pitting corrosion resistance index PI value = Cr% + 3.3Mo% + 30N% -45C% satisfying 10.0 or more (Steel IV of the present invention) ).

Eighth Embodiment As described above, the inventors of the present invention disclosed in Japanese Patent Application No. 7-271111.
Invented, the invention was made to further improve the performance of conventional stainless steel at low cost, but further studies were conducted to further improve the corrosion resistance and high-temperature life, and high core toughness was disclosed in JP-A-9-287058. A rolling bearing having both corrosion resistance and high-temperature life and suitable for use in aircraft, especially jet engines and gas turbines used under high-temperature and high-speed conditions has been developed.

However, the present invention also requires that the material be cut into a shape close to the shape of the finished product and then subjected to a nitriding treatment before quenching. In some precision machine products, such as quenching a round bar, solid grinding may be used to collectively form grooves.In this case, the machining allowance is very large below the rolling surface, so the surface hardening type Therefore, there has been a demand for development of a low-cost stainless steel for soot-burning type bearings having excellent corrosion resistance and high-temperature life.

Therefore, the inventors of the present invention have conducted intensive studies to further enhance the performance of the alloy, and have produced extremely excellent corrosion resistance and corrosion resistance without generating coarse eutectic carbide and δ ferrite which are harmful to the rolling fatigue life. We have invented a bearing stainless steel having a high-temperature life.

A rolling bearing and other rolling devices according to the present invention for achieving the above object comprise an outer member, an inner member, and a plurality of rolling members disposed between the outer member and the inner member. A rolling member that rolls with respect to a first contact surface that is a contact surface with a rolling element and a second contact surface that is a contact surface of an inner member facing the rolling member with the first contact surface. At least one of the side member, the inner member and the rolling element is
And C: 0.45% or less, Cr: 15% to 20%,
Mn: 0.1% or more and 0.8% or less, Si: 0.1% or more and 1.0%
Below, N: 0.05% or more and less than 0.2%, Mo: 0.5% or more
3.0% or less, further Ni: 1.5% or less, Cu: 2.0% or less, Co: 1.0% or more and 7.0% or less, V: 1.0% or less, and the balance Fe and inevitable components. Mo + V: 0.8% or more and 4.0% or less, Co + Ni; 2.0% or more and 8.0% or less, C
Is a relational expression eq1 indicating that the relationship between Cr and the Cr content is C% ≦ −0.05Cr + 1.41 and the content of the element promoting the ferrite formation of the material, and the relational expression eq2 indicating the content of the element promoting the austenitization of the material. [Eq1] = Cr% + Si% + 1.5Mo% + 3.5V%, [eq2] = C% + 0.83N% + 0.12Mn% + 0.05
(Ni + Co)% + 0.02Cu%, and the relationship between the two and the layer content of C and N is [eq2] ≧ 0.04 × [eq
1] −0.39, [eq2] ≦ 0.8, C + N ≧ 0.4%, and PI value of pitting corrosion resistance = Cr% + 3.3Mo% + 3
It is characterized by being constituted by martensitic stainless steel (steel V of the present invention) in which 0N% -45C% satisfies 10.0 or more.

Description of Action and Content of Each Element When Steel I of the Present Invention (Martensitic Stainless Steel) is Used (First and Sixth Embodiments) The critical significance of each component of the steel I of the present invention is as follows. It is as follows.

(C) C is an element which improves hardness after quenching / tempering by converting the matrix into martensite to increase the strength, but the smaller the better, the better the corrosion resistance. When added in a large amount, Cr forms coarse eutectic carbide during steelmaking. As a result, not only the Cr concentration in the matrix becomes insufficient and sufficient corrosion resistance cannot be obtained, but also the fatigue life, toughness and workability are reduced. Therefore, the carbon content was set to 0.6% by weight or less. However, from the viewpoint of corrosion resistance and workability, the content is 0.5% by weight or less, and more preferably 0.45% by weight or less.

(Cr) Cr is the most necessary element for imparting corrosion resistance to steel, but if it is less than 10.0% by weight, good corrosion resistance cannot be obtained. Also, when the Cr content increases, the corrosion resistance improves, but when added more than necessary, δ ferrite and eutectic carbide tend to be formed, and the toughness or fatigue life decreases, and further, the workability also deteriorates. 14
% Or less. Preferably 11.5% by weight or more and 13.5%
% By weight or less.

(Mn) Mn is an element necessary as a deoxidizing agent in steel making and is added in an amount of 0.1% by weight or more. When added in a large amount, not only does cold workability and machinability deteriorate, but also S , P
And so on, which may lower the corrosion resistance and, in some cases, increase the amount of retained austenite to make it difficult to obtain sufficient quench hardness, so that 0.8% by weight or less, preferably 0.1% by weight or less. 5% by weight or less.

(Si) Si, like Mn, needs to be 0.1% by weight or more as a deoxidizing agent in steel making. Further, it is an element effective for increasing the temper softening resistance and for improving the rolling fatigue life. However, when added in a large amount, it reduces toughness and cold workability and promotes the formation of δ ferrite. 0.0% by weight or less.

(Mo) Mo has the effect of significantly increasing hardenability and temper softening resistance. Further, it effectively acts on corrosion resistance. However, if added excessively, not only the toughness but also the hardness after annealing increases, and as a result, the cold workability and machinability decrease, and not only the material cost but also the manufacturing cost of the bearing increases, so that 0 0.5% by weight or less.

(V) V is a strong carbide and nitride forming element, has a remarkably high strength, and tends to work effectively in corrosion resistance. However, if a large amount is added, not only the toughness but also the hardness after annealing is increased, and as a result, the cold workability and machinability are reduced, and not only the material cost but also the manufacturing cost of the bearing are increased. 0.2% by weight or less.

(N) N, like C, has the effect of strengthening martensite to improve corrosion resistance and wear resistance, and also has the effect of suppressing the formation of coarse eutectic carbides.
Preferably, 0.05% by weight or more is added.

In general, in the steelmaking process under normal atmospheric pressure conditions, the nitrogen solubility in the molten steel and the primary ferrite is low. Therefore, it is not possible to add 0.2% by weight or more of nitrogen in the components of the steel of the present invention. When it is very difficult to add a large amount of nitrogen, bubbles are generated during the coagulation process and a large amount of pores are introduced into the ingot, thereby impairing the soundness of the material.

In order to add 0.2% by weight or more of nitrogen, it is possible to make steel in a high-pressure nitrogen atmosphere. However, in this case, enormous equipment costs are required and cost increases. Is not preferred.

For the above reasons, the nitrogen content was set to less than 0.2% by weight. Nitrogen is also an austenite stabilizing element, and in some cases (especially in the case of direct-acting guide bearings, during overheating during induction hardening), the amount of residual austenite increases and the quench hardness may decrease. Therefore, the content is preferably 0.18% by weight or less, more preferably 0.14% by weight or less.

(C + N) In order to obtain a surface hardness of HRC 58 or more and sufficient abrasion resistance after quenching / tempering, C + N is required to be in the range of 0.
45% by weight or more is required. Also, if the total content of carbon and nitrogen is too large (especially in the case of direct-acting guide bearings,
C + N is preferably set to 0.7% by weight or less, since the cold workability decreases due to an increase in hardness after annealing or work hardening.

(Relational expression) In the present invention, (eq1) = Cr%
+ Si% + 1.5Mo% + 3.5V%, (eq2) = C%
+ 0.83N% + 0.12Mn%, and the correlation between the two equations and the total content of carbon and nitrogen is (eq2) ≧ 0.04 × (e
q1) -0.39, eq1 ≦ 14.0, eq2 ≦ 0.8
And

Each of the elements C, N and Mn is an austenite stabilizing element. On the other hand, Cr, Si, Mo, and V are ferrite stabilizing elements.

The formula (eq2) ≧ 0.04 × (eq1) −
If 0.39 is not satisfied, δ ferrite harmful to toughness may be formed. Eq1 ≦ 14.0, e
If q2 ≦ 0.8 is not satisfied, good workability cannot be obtained due to an increase in hardness after annealing, and a decrease in hardness due to stabilization of retained austenite cannot be achieved to achieve a long life. Preferably, eq2 ≦ 0.7.

The upper limit of the carbon concentration is set to C% ≦ −0.05.
If the content is not limited to Cr% + 1.41, coarse eutectic carbides are generated, and the acoustic characteristics, fatigue life, toughness, etc. are reduced.
In addition, even if C% ≦ −0.05Cr% + 1.41,
Eutectic carbide is 5 to 20 μm due to the solidification rate during steelmaking
Although it is often observed that the coarsening to a degree or more, the stainless steel used for the rolling bearing of the present invention contains nitrogen which has an action of suppressing the coarsening of the eutectic carbide. C% ≦ −0.05C
If r% + 1.41 is satisfied, formation of coarse eutectic carbide can be suppressed.

For the above reasons, the steel I of the present invention has a mixed structure of fine carbides, nitrides and ferrites of 10 μm or less after annealing, and has a proper content of C + N and other alloy components. Since the material hardness and work hardening ability can be reduced compared to conventional steels such as SUS440C and 13Cr martensitic stainless steel, especially in the case of linear guides and ball screw devices, it is particularly excellent in cold workability and sufficient by induction hardening. It is easy to obtain a hardened and hardened layer, the variation in heat treatment quality can be suppressed, and the reliability of the device can be improved.

The inner ring, the outer ring and the rolling elements may be constituted by the steel I of the present invention described above. However, more preferable effects can be obtained by using high-carbon Cr martensitic stainless steel for the rolling elements. This will be described below.

(High-Carbon Cr Martensitic Stainless Steel for Rolling Element) When a bearing is made of a single material using conventional high-carbon Cr martensitic stainless steel, the accuracy is lower than that of a bearing steel bearing. When rotating, carbides interfere with each other on the contact surface, and sufficient acoustic performance and fatigue life cannot be obtained.

Further, these stainless steels are poor in mechanical strength and workability, and thus are unsuitable especially for application to inner rings and outer rings. Since the steel I of the present invention has a fine carbide and good mechanical strength and workability, it is particularly effective for application to inner rings, outer rings and the like. Therefore, when the bearing is formed by using the steel I of the present invention for the material of the bearing ring side and high carbon Cr martensitic stainless steel for the material of the rolling element side, mutual interference of coarse carbides is suppressed, and the sound and fatigue life are reduced. And a ball bearing having good mechanical strength can be provided.

Furthermore, high carbon Cr martensitic stainless steel has a large amount of hard carbide such as M7C3 or M23C6, and these carbides have non-metallic properties, and the metal-metal contact area is relatively reduced. And, since the passive film generated on the surface of stainless steel may have a wear reducing effect, while having good wear resistance,
This has the effect of significantly suppressing wear of the mating member. In order to obtain a favorable effect, the area ratio of carbide is desirably 3% or more. Also, if the amount of carbide is too large, the crushing strength of the rolling element may be significantly reduced and lead to breakage,
The upper limit is 20% or less.

For the above reasons, it is possible to obtain a more preferable effect when the bearing member is formed by using the steel I of the present invention as the mating member and using the high carbon Cr martensitic stainless steel as the rolling element.

When the steel III of the present invention was used (fourth and fifth steels)
Embodiments) The effects of the alloy components of the steel III of the present invention, the reasons for limiting the component ranges, and other critical significances are as follows.

(C) The reason for limiting the C content range is that the steel of the present invention I
In particular, in order to obtain the hardness and fine carbide required for rolling bearings for various spindles, various spindle motors and HDDs, the carbon content should be 0.30% by weight or more and 0.45% by weight or less. , Preferably 0.40 to 0.45% by weight.

(Cr) The reason for limiting the content range of Cr is the same as that of the steel I of the present invention, and the content is particularly 10.5% by weight.
Or more and 13.5% by weight or less, preferably 12.0% by weight or more and 13.5% by weight or less.

(Mn, Si) The same as the steel I of the present invention.

The reason for limiting the (N) content is the same as that of the steel I of the present invention. For such a reason, the content of nitrogen is 0.19.
% By weight or less. Further, nitrogen is also an austenite stabilizing element, and in some cases, the amount of retained austenite increases and the impact resistance may decrease, so that it is preferably 0.16% by weight or less, more preferably 0.14% by weight or less. And

(C + N) C and N are elements necessary to obtain the hardness and fretting resistance required for bearings by forming a solid solution in martensite or forming carbides or nitrides. The total amount is 0.5% by weight or more. Is required.

The acoustic performance of the (O, Ti + 0.1Al) rolling bearing is adversely affected by the coarse eutectic carbide and the hard nonmetallic inclusions described above. O (oxygen) in steel is often combined with Al or the like as an unavoidable component and remains as alumina-based inclusions, and is relatively easily coarsened, which may adversely affect acoustic performance. Therefore, oxygen is 20 pp
m, preferably 10 ppm or less. Also, Al and Ti are combined with N (nitrogen) to form very hard A
Since they remain as 1N and TiN and adversely affect acoustic performance similarly to alumina-based inclusions, the total content of Ti + 0.1Al is limited to 50 ppm or less.

(S) S is an element harmful to corrosion resistance, and is preferably as small as possible, and more preferably 100 ppm or less in order to sufficiently exert its effect. However, the machinability of stainless steel is inferior to that of SUJ2. When S is reduced, not only does machinability decrease, but excessive cleanliness also raises material costs. No tempering is performed.

(The carbide contained has a particle size of 2.0 μm or less,
(Area ratio 5% or less) In order to obtain good acoustic performance, the contained carbide has a particle size of 2.0 μm or less and an area ratio of 5% or less.

When the Specific High Carbon Steel is Used The critical significance of each element of the specific high carbon steel of (4) used in the second and fifth embodiments is as follows.

(C) Carbon is an element effective for obtaining the hardness required for bearings, and it is necessary to use a low-cost heat treatment mainly for quenching and tempering when corrosion resistance is not required. Considering the above, in order to obtain a long life and abrasion resistance, a value of 0.
It is effective to add 8% or more.

However, when the content exceeds 1.5% by weight, coarse carbides are generated, so that long-time soaking is required or workability is reduced, which leads to an increase in cost. For the above reasons, the carbon content of the material is set to 0.8% by weight or more and 1.5% by weight or less. From the viewpoint of workability, in order to further reduce the material cost, the content is preferably 0.9% by weight or less.

(Cr) Cr has the effects of increasing hardenability and resistance to tempering softening, and also has the effect of forming carbides to suppress coarsening of crystal grains during heat treatment and imparting wear resistance. However, when the content exceeds 2.0%, soaking for a long time is required or workability is deteriorated, so that the cost of adding Cr and the material cost are increased. For the above reasons, the Cr content of the material is set to 0.1% by weight or more and 2.0% by weight or less. In order to further reduce the material cost from the viewpoint of workability, the content is preferably set to 0.6% by weight or less.

(Mn) Mn is a necessary element as a deoxidizing agent in steel making, and is added in an amount of 0.1% by weight or more. When added in a large amount, not only does the machinability deteriorate, but also in some cases the amount of retained austenite is reduced. 0.1% by weight or more (especially 0.5% by weight or more when the amount of Cr is 0.6% by weight or less) since sufficient quenching hardness may not be obtained due to an increase in
1.5% by weight or less, preferably 1.1% by weight or less.

(Si) Si needs to be 0.1% by weight or more as a deoxidizing agent at the time of steel making like Mn. Further, it is an element effective for increasing the tempering softening resistance and improving the rolling fatigue life. However, if added in a large amount, the machinability is reduced, so the content is set to 1.0% by weight or less. From the viewpoint of workability, in order to further reduce the material cost, the content is preferably set to 0.7% by weight or less.

Next, in the second embodiment, the reason why the rolling element as a mating member combined with the rolling member made of the above specified high carbon steel is made of high carbon Cr martensitic stainless steel is as follows. is there.

(High Cr martensitic stainless steel) When fretting resistance was evaluated using a single material of high carbon steel and high Cr stainless steel, stainless steel was extremely good. Thereby, the fretting damage of the high carbon steel is suppressed and remarkably improved.

On the other hand, stainless steel tends to be slightly more susceptible to fretting damage than the case where a single material is evaluated. Not only is the effect small, but the properties inherent in stainless steel cannot be fully exhibited.

A problem with the rolling bearing for the HDD swing arm is fretting damage to the raceway, and in order to achieve a sufficient effect in terms of cost and function, use low-cost high-carbon steel for the raceway. It is preferable to use stainless steel for the rolling elements. Although the workability is inferior to that of high carbon steel, the rolling elements (balls) are mostly forged by forging compared to race rings that require relatively many man-hours, so that there is not much problem with using stainless steel.

In addition, by using high carbon steel for the race, the accuracy of roughness is improved, interference between carbides on the contact surface is eliminated, and the acoustic performance is improved. In addition, high-carbon steel such as bearing steel has a slightly higher hardness than stainless steel, so internal friction can be reduced, and the use of stainless steel for the rolling elements reduces the specific gravity of the rolling elements. -The rotational torque tends to be slightly reduced, and the present invention can be suitably used not only for rolling bearings used for transporting various spindles or various spindle motors, but also for swing arms for HDD devices, and the like.

(N) Preferably 0.05 to 0.2% by weight is added. In addition to the reason for the first object, in particular, when the bearing ring or shaft as the mating member is the above-described carbon steel, the stainless steel is alloyed with nitrogen, so that the carbon steel as the mating material to be brought into contact is formed. A transition film is easily formed on the surface, which is very effective in reducing fretting wear. For the above reasons, at least 0.05% by weight or more is added.

When Steel IV of the Present Invention is Used (Seventh Embodiment) The critical significance of the content of each element in steel IV of the present invention is as follows.

(C) C is an element that increases the hardness after quenching / tempering by transforming the matrix into martensite to increase the strength, but the smaller the better, the better the corrosion resistance. When added in a large amount, a coarse eutectic carbide is formed by carbide-forming elements such as Cr and Mo during steelmaking, and the rolling life and corrosion resistance are remarkably deteriorated. Therefore, the C content is set to 0.45% by weight or less. Furthermore, from the viewpoint of corrosion resistance,
Preferably, it is not more than 0.4% by weight.

(Cr) Cr is the most necessary element that imparts corrosion resistance to steel, and when corrosion resistance is particularly important, 15.0% by weight or more is required to exert its effect remarkably. Also, if Cr is added more than necessary, δ ferrite is formed and becomes brittle, or depending on the carbon content, carbides may be coarsened and the corrosion resistance may be reduced, so the upper limit is set to 20.0% by weight. Preferably 17% by weight
Not less than 19% by weight.

(Mn) Mn is an element necessary as a deoxidizing agent in steel making and is added in an amount of 0.1% by weight or more. However, if added in a large amount, residual austenite is easily formed, and sufficient quenching hardness cannot be obtained. Therefore, the upper limit is set to 0.8% by weight, preferably 0.5% by weight or less.

(Si) Same as the steel I of the present invention.

(N) N, like C, has the effect of strengthening martensite, increasing quenching hardness, further improving corrosion resistance, and suppressing the formation of coarse primary eutectic carbides. 0.05% by weight or more, preferably 0.08% by weight or more. However, when a large amount is added, bubbles are generated due to the low solubility of the primary ferrite crystallized in the solidification process during ordinary melting, and as a result, a large amount of pores are introduced into the ingot, and the soundness of the material is lost. It is also possible to add a large amount of nitrogen without impairing the soundness of the material by a steelmaking method or a surface infiltration method in a high-pressure nitrogen atmosphere, but in this case, the cost of the material or the heat treatment increases. . From the above, it is preferable to perform the dissolution by ordinary dissolution from the viewpoint of cost.

(Mo) Mo has the effect of significantly increasing hardenability and temper softening resistance. Further, it has an effect of improving pitting corrosion resistance, so that 0.5% by weight or more is added. However, if added in excess, the toughness, workability and the like are reduced, so the upper limit was made 3.0% by weight.

(Ni) Ni is a strong austenite stabilizing element and has an effect of suppressing the formation of δ ferrite, improving toughness, and also improving corrosion resistance. Is added. However, if it is added more than necessary, a large amount of retained austenite may be formed and sufficient quenching hardness may not be obtained, so the upper limit was made 1.5% by weight.

(Cu) Cu is also a slight austenite stabilizing element like Ni, and suppresses the formation of δ ferrite.
Further, since it has an effect of improving corrosion resistance, it is preferably added in an amount of 0.1% by weight or more. However, if a large amount is added, hot cracking may occur in the hot forging step required in the manufacturing process of the bearing, and sufficient quenching hardness may not be obtained. And

(Inevitable Components) Normally, steel contains impurities such as P, S, and O in addition to the above main elements. In the invention of the present application, the cleanliness is not increased more than necessary in terms of cost, but in particular, when the amounts of S and P are large, they segregate or reduce the corrosion resistance. Good, preferably limited to 0.03% by weight or less. In addition, since O forms oxide-based inclusions and reduces the fatigue life and the like, it is desirable that the amount of impurities in steel is as small as possible, and it is preferably limited to 50 ppm or less.

(C% ≦ −0.05Cr% + 1.41) If the above formula is not satisfied, coarse eutectic carbides are formed, leading to not only rolling fatigue life but also significant deterioration of corrosion resistance. .

((Eq2) ≧ 0.04 × (eq1) −0.3
9, (eq1) = Cr% + Si% + 1.5Mo%, (eq
2) = C% + 0.83N% + 0.12Mn% + 0.05
(Ni% + 0.02Cu%) The elements described in eq1, that is, each element of Cr, Si, and Mo are ferrite stabilizing elements, and the elements described in eq2, that is, C, N,
Mn, Ni, and Cu are austenite stabilizing elements.
Therefore, if the component system does not satisfy the above inequality,
In some cases, the ferrite is stabilized and δ ferrite harmful to toughness is generated.

(C + N ≧ 0.4%) The minimum C required to obtain the hardness required for the bearing due to martensite strengthening, precipitation hardening, etc.
+ N needs to be 0.4% by weight, preferably 0.45% by weight or more.

(Pit corrosion resistance index PI value = Cr% + 3.3M)
o% + 30N% -45C% ≧ 10.0) In general, the evaluation of corrosion resistance of stainless steel is often performed by a salt spray test or pitting potential measurement. The salt spray test is the simplest evaluation method, but it is not suitable for quantifying the degree of difference in corrosion resistance.If quantitative evaluation of corrosion resistance is desired, the polarization measurement method is used. In many cases, the pitting potential Vc 'is measured and compared and evaluated. The greater the pitting potential, the better the corrosion resistance, indicating that
In austenitic stainless steel, the pitting resistance index PI (pitting index) = aCr% + bM
It is said that there is a correlation with a relational expression of o% + cN%.
That is, it is shown that the higher the content of Cr, Mo, and N, the better the corrosion resistance, and the concept of the pitting corrosion resistance index is often used for the component design of the austenitic stainless steel. However, this conventional pitting resistance index can be applied to austenitic or ferritic steels containing almost no carbon, and cannot be applied to martensitic stainless steel containing carbon. Therefore, the inventors of the present application have conducted intensive studies and investigated the effect of carbon on corrosion resistance. as a result,
If the composition range satisfies C% ≦ −0.05Cr% + 1.41, PI = Cr% + 3.3Mo% + 30N% −4
It was derived that it was highly correlated with 5C%.

The present inventor has found that when no coarse eutectic carbide is contained, there is a good correlation between the above-mentioned PI value and the pitting potential Vc ′ (100) that indicates the corrosion resistance of steel. It has been found that very high corrosion resistance can be obtained by securing 10 or more. For the above reasons, the PI value is set to 10.0 or more in the present invention.

When Steel V of the Invention is Used (Eighth Embodiment) The critical significance of the content of each element in steel V of the invention is as follows.

[C], [Cr], [Mn], [Si],
[N], [Mo], [Ni], [Cu], [unavoidable components], [relationship between C and Cr], [C + N], and [PI value] are the same as those of steel IV of the present invention.

[Co] Co, like Ni, is an austenite stabilizing element, suppresses the formation of δ ferrite, and further improves tempering softening resistance and high-temperature hardness by strengthening the solid solution of the matrix and suppressing the aggregation of carbides. Has the effect of causing. Therefore, it is added in an amount of 1.0% by weight or more. However, if added in a large amount, the workability is lowered and the material cost is significantly increased, so the upper limit was made 7.0%.

[V] V is a strong carbide / nitride forming element, and finely precipitates in the matrix to contribute to precipitation strengthening. In particular, when tempered at a high temperature, it acts on secondary hardening and has the effect of increasing the room temperature hardness. Therefore, selectively
Although it is added up to 1.0% by weight, if it is added in a large amount exceeding 1.0% by weight, carbides are coarsened in the solidification process and workability such as machinability is remarkably reduced.

[[Eq2] ≧ 0.04 × [eq1] −0.3
9, [eq1] = Cr% + Si% + 1.5Mo% + 3.5V%,
[Eq2] = C% + 0.83N% + 0.12Mn% + 0.05
(Ni + Co)% + 0.02Cu%, [eq2] ≦ 0.8] The elements described in eq1, namely, Cr, Si, Mo,
Each element of V is a ferrite stabilizing element, and the elements described in eq2, namely, C, N, Mn, Ni, Co,
Cu is an austenite stabilizing element. Therefore, if the component system does not satisfy the above inequality, the ferrite may be stabilized and δ ferrite harmful to toughness may be generated. When eq2 is 0.8 or more, austenite may be stabilized and sufficient quenching hardness may not be obtained.

[0166]

<Example I> This example corresponds to the first embodiment.

The test materials and comparative steels of the present invention were prepared as shown in Table 1. Table 2 shows the results of evaluation of workability by a reduction test, a drilling test, and a grinding test. The test conditions are shown below. The heat treatment was performed at a heating temperature of 1020 to 1070 ° C.
Immediately after quenching in quenching oil, a sub-zero treatment at −80 ° C. × 1 hr was performed and tempering was performed at 160 to 200 ° C. × 2 hr.

(Cutting test conditions) Cutting method: Dry feed rate: 0.1 to 0.2 mm / rev Cutting depth: 0.5 to 1.0 mm Cutting tool: P10 (JIS B 4053) Cutting speed: 80 to 100 m / Min (Drill drilling test conditions) Drill tool: φ8mm, SKH51 Drilling method: Dry type Drilling depth: 10mm Cutting speed: 21m / min (840rpm) Thrust: 70kg (Grinding test conditions) Grinding wheel: WA80 (Creamton) Grinding Liquid: Soluble type Wheel peripheral speed: 1500-2700m / min

[0169]

[Table 1]

[0170]

[Table 2] None of the steels of the present invention have coarse eutectic carbides.
As is clear from Tables 1 and 2, C, Si, Mn,
Since the alloy components such as Cr and Mo, V, etc. are limited and the increase in hardness after annealing is minimized, the machinability, grindability, and even the roughness after grinding finishing are small, and in all cases Good. In contrast, G, which is a reference example,
H, I, and K do not satisfy eq1 ≦ 14.0, and the hardness after annealing relatively increases, and good workability cannot be obtained. In Reference Example N, not only is C% 0.6% or more, but eq2 ≦ 0.7 and C% ≦ −0.05Cr% + 1.
Since the relational expression of 41 or the like is not satisfied, coarse carbides are formed and workability is poor. Reference Example O was excluded from the evaluation because delta ferrite was formed.

Table 3 shows the life test results, the impact test results, and the salt spray test results.

In the salt spray test, after the outer ring of the bearing was completely degreased with acetone, it was tested according to JIS standard Z2371.
C., using a 5% NaCl solution for a test time of 50 hours.
The appearance was determined later. In the table, the degree of rusting was observed, and the results were evaluated in three grades of ○, Δ, and × from good ones.

For the life test, a thrust-type rolling life tester described on pages 10 to 21 of “Special Steel Handbook”, 1st edition (edited by Denki Steel Research Institute, Rigaku Corp., published May 25, 1969) was used. Performed under the following conditions, and the number of cumulative stress repetitions up to the point when flaking occurred in each sample (life)
And a Weibull plot was created, and each L10 life was determined from the results of each Weibull distribution.

The impact test was performed on a JIS No. 3 test piece (2 m
m depth 5RC notch) at room temperature.

(Life test) Test surface pressure: 5200 Mpa Rotational speed: 3000 C.P. P. M. Lubricating oil: # 68 turbine oil

[0176]

[Table 3] From Table 3, it can be seen that in Examples, fine carbides were used, the amount of carbides was small, and the effects of nitrogen addition also provided good results in impact strength, corrosion resistance, and fatigue life. M and N, which are reference examples, are slightly inferior to the steel of the present invention in all because the carbides are slightly coarse and the amount of carbides is large and there is no influence of nitrogen addition.

In Reference Example L, good workability was obtained, but the content of C + N was insufficient, sufficient hardness was not obtained, and good rolling life was not obtained. From the above, it has been found that the steel of the present invention has good workability and good rolling life and corrosion resistance. Therefore, it is found that an inexpensive and high-performance bearing can be provided by forming a bearing using this material.

Table 4 shows the results of evaluation of acoustic performance or fretting resistance, which are required characteristics of various types of spindles, various types of spindle motors, and ball bearings for swing arms for HDD devices and the like. The fretting resistance was evaluated using the fretting durability tester shown in FIG. 1 under the following conditions, and the inner ring wear depth was measured and evaluated.

In FIG. 1, reference numeral 10 denotes a preload spring fixed to a shaft, 12 denotes a shaft rotation stop, 14 denotes a shaft, 16 denotes a housing, and 18a, 18b and 18c denote a member formed separately from the shaft. ) Sleeve, 20 is a test bearing, 22 is a disc spring for pressing the sleeve in the axial direction, 24 is a support bearing, 26
Is an AC servomotor. The shaft and the inner ring do not rotate, and the housing and the outer ring are rotatably supported. As shown in FIG. 2, the preload is applied to the inner ring 20-2, the outer ring 20-1 and the rolling element 20A of the uppermost test bearing 20 by pressing the sleeve 18a. It is transmitted to the bearing 20.

(Fretting durability test) Test bearing: SR1810 Lubrication: Mineral oil-based grease Frequency: 30 Hz Load: 9.8 N Swing angle: 8 ° Number of cycles: 200 million times

[0181]

[Table 4] From Table 4, it can be seen that the steel of the present invention has no coarse carbides, has high hardness, and therefore has excellent acoustic performance and low torque. In addition, due to the effect of nitrogen and the like which contribute to wear resistance as well as high hardness, the fretting resistance is also good, and the effect is particularly great when the rolling element is made of high carbon Cr stainless steel.

On the other hand, in Reference Example No. Nos. 6 and 7 are examples in which both the race and the rolling element are made of conventional high-carbon Cr stainless steel. However, due to the presence of coarse carbide, the acoustic performance is slightly inferior and the amount of N is small.
o. In No. 6, the fretting resistance tends to be slightly inferior. Further, the hardness tends to be slightly insufficient, and the torque tends to increase due to internal wear. Reference Example No. In No. 8, the content of C + N was less than 0.45, the hardness was insufficient, and the fretting resistance was significantly reduced.

As described above, the present invention not only improves the function as a conventional stainless steel but also imparts good workability, and thus can be suitably used as a bearing material to be machined.

<Example II> This example corresponds to the second embodiment.

The test materials of the present invention were prepared as shown in Table 5.

[0186]

[Table 5] Table 6 shows the heat treatment conditions of the test materials, and embodiments and reference examples in the present invention. In addition, various spindles,
The fretting resistance, which is a required characteristic of a ball bearing used for a swing arm for various spindle motors and HDD devices, was measured using the fretting durability tester shown in FIG. 1 under the conditions described below. Further, the torque before and after the test, the torque fluctuation width, and the like were measured and evaluated. The magnitude and fluctuation range of the torque were measured by rotating the bearing at 360 ° at a speed of 2 rpm, and evaluated using the average value and the fluctuation range, respectively.

(Fretting test conditions) Test bearing: SR1810 Lubrication: Mineral oil grease Frequency: 30 Hz Load: 9.8 N Swing angle: 8 ° Number of cycles: 200 million times

[0188]

[Table 6] As shown in Table 6, in this example, the bearing was formed using the specific high carbon steel of (4) above for the race and the high Cr martensitic stainless steel for the rolling elements, so that there was no mutual interference between coarse carbides. In addition, improved roughness accuracy and hardness on the raceway side have achieved good acoustic performance and low torque.
Further, by using stainless steel for the rolling elements, fretting damage on the raceway side was reduced, and deterioration in the function of the bearing was suppressed.

In particular, a rolling element made of nitrogen-containing stainless steel has a great effect of suppressing fretting damage, and also has a tendency to improve acoustic performance since carbides are suppressed from being coarsened. In addition, when P having 0.9% by weight or less of C and 0.6% by weight or less of Cr is used as the high carbon steel constituting the rolling element, the acoustic characteristics and the torque tend to be further improved. Recognize. On the other hand, in the reference example No. 1; 17, No. 18 and no. 1
9 has good acoustic performance because both the race and the rolling elements are made of high-carbon steel, but is susceptible to fretting damage and has a markedly reduced function as a bearing.

In addition, No. 20, no. 21 is a bearing ring,
Although the rolling elements are made of stainless steel, the cost is high and the fretting damage is relatively small,
Sufficient acoustic performance cannot be obtained due to mutual interference between carbides and a decrease in roughness accuracy. In addition, No. 22 is made of a bearing using stainless steel for the bearing ring and high-carbon steel for the rolling element, so that not only is the cost reduction effect small, but also the acoustic performance is slightly inferior to the example of the present invention, and the torque and torque fluctuations are small. large.

Further, the bearing ring and the rolling elements are more susceptible to fretting damage than when they are made of stainless steel, which impairs the function originally provided by stainless steel, which is not preferable.

As described above, the high-carbon steel is used for the outer ring, the inner ring or the shaft, and the raceway side, and the bearing is formed using the high-Cr stainless steel for the rolling elements. A ball bearing for a swing arm for a motor or an HDD device can be provided.

<Example III> This example corresponds to the third embodiment.

In the material of the outer ring and the inner ring, carbide having extremely fine carbide and secondary hardening ability: 0.40 to 0.45
%, N; 0.05 to 0.20%, Cr; 12 to 13.5
%, Mn: 0.1 to 0.8%, Si: 0.1 to 1.0
%, C + N ≧ 0.5%, balance Fe and martensitic stainless steel as an unavoidable component were used.

Table 7 shows the results of comparing the sound measurement results and the fretting durability test results of the ball bearing of this embodiment with those of the conventional ball bearing. The material according to the present embodiment uses the above martensitic stainless steel, is quenched at 1020 ° C. to 1070 ° C., then subjected to a secondary hardening treatment at 450 ° C. × 2 hours, and then cut, and then subjected to 410 ° C. × 24 hours. A nitride layer is formed on the surface layer by a gas nitriding method, and then a finish layer is used.
(2% of Da; 31.8 μm)
As described. As a reference, Table 8 shows a comparison with the case of the conventional nitriding treatment at 530 ° C., but in this embodiment, the surface roughness and the roundness are less deteriorated compared to the reference example, and the grinding allowance is relatively small. It is effective as a heat treatment method for a very small diameter ball bearing for information equipment requiring high accuracy.

Table 7 shows SUJ2 used for various conventional ball bearings for spindles and C used for ball bearings for swing arms used in HDDs and the like;
60-0.75%, Cr; 10.5-13.5%, M
n: 0.3 to 0.8%, the balance Fe and 13Cr martensitic stainless steel as an unavoidable component were described as B in Reference Examples.

The fretting durability tester shown in FIG. 1 was used. For test bearings, fix the inner ring and connect the outer ring to AC
Vibration was performed by a servomotor, and the test was performed under the following conditions.

Test bearing: 695 Lubrication: Mineral oil-based grease Frequency: 27 Hz Load: 1.5 kgf Vibration angle: 2 ° Number of cycles: 100,000 times As is clear from Table 7, the conventional SUJ2 described in Reference Example 35 Although the ball bearings for spindles have good acoustic characteristics, the acoustic level after the fretting durability test is greatly reduced, and the fretting resistance is not sufficient. On the other hand, the conventional 13Cr martensitic stainless steel ball bearing for a swing arm described in Reference Example 36 has a lower acoustic level after the fretting durability test than the SUJ2 ball bearing, and has a lower fretting resistance. Good, but inferior in sound level to SUJ2 ball bearings.

On the other hand, Embodiments 31 to 34 of the present application are examples in which the steel of the present invention is used for either the bearing ring or the rolling element. The fretting resistance has also been improved. Further, as shown in Example 34 of the present application, the fretting resistance tends to be further improved when the rolling elements are made of ceramic balls when a slight increase in cost is expected.

As described above, according to the present invention, it is possible to provide a ball bearing with improved fretting resistance and excellent acoustic characteristics.

In the present embodiment, as the steel A, the one containing no Mo is used in consideration of the material cost, but within 3% by weight (preferably 0.5% by weight or less in terms of cost). ), The secondary curing ability can be further improved. Other materials may be used as long as they have a secondary curing ability and have a material of HRC 57 or higher.

[0202]

[Table 7]

[0203]

[Table 8] <Example IV> This example corresponds to the fourth embodiment.

The test materials of the present invention were prepared as shown in Table 9. A cutting test was performed under the same conditions as in Example 1.

Tables 10 and 11 show the results of the evaluation of the heat treatment quality, and Table 12 the results of evaluation of the acoustic performance, fretting resistance, corrosion resistance and the like of the ball bearing 695. SUJ2 in the table
Manufactured by the company are also described for comparison. A to F are quenching temperature 1
After gas cooling at 030 ° C, sub-zero treatment at -80 ° C
It was subjected to a tempering test at 0 ° C.

Regarding the particle size of the carbide, 20 fields of view were observed with a scanning electron microscope at a magnification of 3000 times, and those having the largest particle size were extracted from each field and converted into a circle-equivalent diameter by image processing. Calculated by averaging minutes. Regarding the area ratio of the carbide, 20 fields of view were observed with an optical microscope at a magnification of 1000 times, and the area ratio of each field was determined by image processing.

The acoustic performance of the above ball bearing was measured using an Anderon meter. B. And H. B. Was measured, and each was described as an average value of n = 20. In addition, in the fretting durability test, the bearing described above was applied to the durability test machine shown in FIG.
The test was performed under the conditions of a frequency of 27 Hz, a vibration angle of 8 °, and a cycle number of 100,000 times, and measuring the Anderon value after the durability test. The lubrication of the bearing was performed under a slight amount of lubrication in which 2 to 3 mg of an ester synthetic oil was applied.

In addition, the corrosion resistance was evaluated according to JIS standard Z23.
The salt spray test according to No. 71 was carried out in the same manner as in Example 1. In the table, the results of a 5-grade evaluation are given, where A is no rusting, B is slightly rusting, C is rusting at 20% or more of the test area, C is rusting almost entirely, and E is significant rusting. did.

[0209] From Table 10, it can be seen from the table that the components of the embodiment of the present invention, including the carbon content, are adjusted to the range where the workability is improved, so that the tool life is improved and the cost can be greatly reduced. The reference example is the case of 13Cr martensitic stainless steel (Reference Examples 44 and 45) and SUS440C (Reference Example 46) which are conventional steels, both of which have a high carbon content in the material and a large number of hard eutectic carbides. Due to the inherent nature, it is inferior to the invention steel in workability.

Further, as is clear from Tables 11 and 12, the embodiment of the present invention has no coarse carbides, and the carbon is reduced and nitrogen is added. It is much better in that respect. Also, O,
In Example 42 in which Ti + 0.1Al was reduced, nonmetallic inclusions harmful to acoustic performance were reduced, and acoustic performance was further improved. Example 43 in which S was additionally reduced
In, the corrosion resistance was further improved. On the other hand, Reference Example 44 is an example of 13Cr martensitic stainless steel, which is a conventional steel, but is inferior to the steel of the present invention not only in acoustic performance but also in corrosion resistance due to the presence of a somewhat large eutectic carbide. I have. Reference Example 45 shows that S and Ti of 13Cr martensitic stainless steel, which is a conventional steel, are used.
+ 0.1Al content is both reduced,
Since the coarse eutectic carbide remains, the effect on acoustic performance or corrosion resistance is inferior to that of the steel of the present invention. Reference Example 46 is an example of SUS440C which is a conventional steel,
Due to the presence of extremely coarse eutectic carbides, both acoustic performance and corrosion resistance are insufficient. Further, Reference Example 47 is an example of SUJ2 currently used for a spindle motor, but has excellent acoustic performance but is insufficient in corrosion resistance and fretting resistance.

As described above, the present invention not only improves the function as a conventional stainless steel but also imparts good workability, so that it can be suitably used as a bearing material to be machined. Ball bearings for information equipment have remarkable effects in both cost reduction and high functionality.

As described above, in the ball bearing of the present invention, the stainless steel material, which is a constituent material thereof, has a bad effect on the corrosion resistance and, when the content is large, forms a coarse eutectic carbide to deteriorate the function. By partially substituting carbon, which is the component to be dissolved, with nitrogen having the same solid solution strengthening action, and further reducing the content of impurity components, coarse eutectic carbide harmful to acoustic performance and corrosion resistance etc. Alternatively, formation of nonmetallic inclusions can be suppressed, and as a result, workability can be improved and a high-performance ball bearing can be manufactured at low cost.

[0213]

[Table 9]

[0214]

[Table 10]

[0215]

[Table 11]

[0216]

[Table 12] <Example V> This example corresponds to the fifth embodiment.

Test materials and comparative steels used as materials for the bearing rings in the present invention were prepared as shown in Table 13. Table 14 shows the materials used for the rolling elements.

The bearing was made of 695, the race was made of the material shown in Table 13, and the rolling elements made of the material shown in Table 14 were subjected to a built-in test. In addition, the material for the bearing rings described in Table 14 was subjected to a quenching temperature of 1030 ° C. and sub-zero treatment.
Tempered at 160 ° C. for 2 hours. At this time, the carbide content of various materials is carbide particle diameter 0.9 μm and carbide area ratio 2% or less in the steels A and B of the present embodiment, while those of the comparative steels C and D are comparative steels. The carbide particle size was 4 μm or more, and the area ratio was 3% or more.

Table 15 shows the combinations of the embodiments of the present invention and the combinations of the comparative examples, and their acoustic performance comparisons. FIG. 4 shows the change over time in the anderon value measured using the bearings shown in Table 15. The measurement of the change over time
Incorporate the bearing into the spindle motor, load 2.0k
gf, a rotation test was performed at a rotation speed of 7,200 rpm.
The operation was stopped every 0 hours, and the anderon value was measured in the same manner. In addition, the corrosion resistance evaluation described in Table 15 is based on JIS standard Z.
After the bearing outer ring was completely degreased with acetone by a salt spray test according to 2371, the test was performed at 35 ° C. using a 5% NaCl solution. ◎ 〜 ○ 〜 良好
The results of four-step evaluation in the order of -X are described.

Table 15 shows that Examples 51 to 55 of the present invention in which the steel according to the present invention was used for the raceway and high-carbon bearing steel was used for the rolling elements had extremely small carbides and the like as compared with the Reference Example, so that the acoustic performance and It is superior to the reference example in terms of corrosion resistance. In Table 15, as a reference example when the inner ring, the outer ring, and the rolling element are all made of a single material, 59 is a case of X steel (SUJ2),
0 describes the case of C steel. Since 60 contains a hard and coarse carbide, it is superior in corrosion resistance to 59, but is inferior in acoustic performance or cost. Only 60 rolling elements are made of X steel or Y
In Reference Examples 56 and 57 using steel (SUJ2), the acoustic performance was remarkably improved, but slightly inferior to 59 made of X steel (SUJ2). Further, in Reference Example 58, the race was made of D steel (SUS440C), and the rolling element was made of X.
This is an example in the case of steel (SUJ2). However, since the carbide is coarser than 56 or 57, it is inferior in acoustic performance. In the invention example of the present application, in particular, a B steel in which the content of O and Ti + 0.1Al is reduced is used for the raceway ring, and a Y steel (SUJ2) in which the content of O and Ti + 0.1Al is also reduced is used for the rolling element. In this case, the acoustic performance was further improved. Furthermore, the rolling elements are C, C more than SUJ2.
When the steel is composed of a Z steel having a small r content, the acoustic performance tends to be further improved because the contained carbide is refined and reduced.

C is 0.8 to 0.9% by weight, and Cr is 0.1% by weight.
It has been confirmed that a range of -0.6% by weight is preferable.

Further, as shown in FIG. 4, in the present invention example, the steel of the present invention used for the bearing ring has a strong passivation effect having an effect of suppressing friction and wear, which may cause damage to the mating member, that is, the rolling element. Since the accuracy is reduced to reduce the accuracy, the deterioration of the acoustic performance with time is very small. In contrast, Reference Example 56,
In No. 58, the effect of suppressing the friction and wear is smaller than that of the steel of the present invention, and the accuracy of the rolling elements is significantly reduced due to the influence of coarse and hard carbides and the durability is inferior. FIG. 5 shows the initial anderon value and the amount of change in anderon after the rotation test was performed for 300 hours. While the Anderon value of the reference example changed significantly after the rotation test, the inventive example of the present invention showed almost no acoustic deterioration even after the rotation test, and it was confirmed that the sample had good durability.

As described above, the present invention particularly provides a ball bearing for information equipment, and has remarkable effects in both cost reduction and high performance.

As described above, in the ball bearing of the present invention, the stainless steel material, which is a constituent material thereof, has a bad effect on the corrosion resistance and, when the content is large, forms a coarse eutectic carbide to deteriorate the function. By partially substituting carbon, which is the component to be dissolved, with nitrogen having the same solid solution strengthening action, and further reducing the content of impurity components, coarse eutectic carbide harmful to acoustic performance and corrosion resistance etc. Alternatively, the formation of non-metallic inclusions can be suppressed, and furthermore, by forming the rolling elements from high-carbon bearing steel or the like, which is advantageous in terms of cost, a ball bearing having high performance and durability can be manufactured at low cost.

[0225]

[Table 13]

[0226]

[Table 14]

[0227]

[Table 15] <Example VI> This example corresponds to the sixth embodiment.

Test materials and comparative steels were prepared as shown in Table 16. Table 17 shows the results of the evaluation of the cold workability. The test piece was hot-rolled to form φ20, then annealed and cut to a length of 25 mm. A complete restraint test was performed on the end face, and the deformation resistance and the cracking of each material when the rolling reduction was 50% were used. The incidence rate was investigated.

[0229] Further, using the similarly manufactured φ65 material, cold drawing was performed under the conditions of 10%, 20% and 30% area reduction, and the work hardening ability (cold work drawing) for each area reduction rate. (Evaluated by later hardness). Furthermore, reduction of area 3
After cold working using 0% test piece, it was left for 24 hours,
The surface was observed, and those with aging cracks were indicated by x in the table.

The steels “a” to “f” of the present invention have low hardness after annealing, and have good deformation resistance and deformability.
Further, the work hardenability with respect to the area reduction rate during cold working was small, and no aging crack was observed. On the other hand, in the reference example, all results were inferior to those of the steel of the present invention except for the “l” steel. For "g" to "k", the alloy component content does not satisfy the range of the embodiment, and since the "m" steel does not contain nitrogen, a little eutectic carbide of about 5 to 10 m is generated. As a result, the cold workability was reduced. In particular, the conventional steels SUS440C or 13Cr martensitic stainless steels "n" to "p" are extremely poor in workability, the work strain remains, and aging cracks occur around coarse carbides as a base point. .

The heat treatment was performed under the following conditions.
Surface hardness (0.15mm depth), hardened layer depth (550H
v), corrosion resistance evaluation by salt spray test, and rolling fatigue life test were performed. The respective test conditions are described below.

[0232]

[Table 16]

[0233]

[Table 17] (Heat treatment conditions) Specimen: φ13.2 × 490 (quenched part is only 400 mm at center) Induction hardening machine: Transmission method Transistor / inverter type Output 200 kW Frequency 30 kHz Hardening condition: 310 V × 24 m / sec (quenching temperature 1050 to 1120 ° C.) Quenching: −80 ° C. × 1 hr after water cooling Tempering: 170 ° C. × 1.5 hr (salt spray test) This test is based on JIS Z2371 and uses a 5% NaCl solution at a temperature of 35 ° C. The test was evaluated by the appearance after 50 hours of the test time, and evaluated according to three grades of ○, Δ, and × from those having good rusting degree.

(Rolling fatigue life test) In the life test, the damage form of the linear motion guide bearing device on the market was observed, and most of the damage was peeling-like surface damage. We conducted a radial life test, investigated the cumulative number of stress repetitions (life) up to the point when flaking occurred in each sample, created a Weibull plot,
Each L10 life was determined from the results of each Weibull distribution.
The test conditions are described below.

Test surface pressure: 450 kgf / mm ² Number of revolutions: 7800 rpm Lubricating oil: S10 turbine oil (manufactured by Idemitsu Oil Co., Ltd.) Rolling element: 27/32 inch balls, 3 balls (average roughness 0.27 μm) 3 (1) shows a plan view of the test apparatus,
(2) is a sectional view taken along line aa ′. 30 indicates a test piece (φ12.9 × 80), 31 indicates a 27/32 inch ball, and 32 indicates a ring. 78 test pieces
Rotate at 00 rpm.

[0236]

[Table 18] From Table 18, it can be seen that, in the invention examples of the present application, carbides and nitrides are fine and uniformly dispersed, so that the conventional steels “n”, “o”,
Compared with "p", sufficient surface hardness and hardened layer depth can be easily obtained even by short-time heating by induction hardening. Further, due to the influence of nitrogen addition, good results were obtained in all of corrosion resistance and fatigue life. The reference example "l" obtained good workability, but was inferior to the steel of the present invention in fatigue strength or corrosion resistance because the total content of carbon and nitrogen was small and the influence of nitrogen addition was insufficient. .

As described above, since the steel of the present invention has good workability and heat treatment productivity and good rolling life and corrosion resistance, it is promising as a martensitic stainless steel for rolling. It has been found that by configuring, a low-cost and high-performance linear motion guide bearing device made of stainless steel can be provided.

<Example VII> This example corresponds to the seventh embodiment.

The test materials and comparative steels are shown in Table 19 for their alloy components.
Prepared as shown in Table 20 shows the results of the heat treatment quality test after the heat treatment, the corrosion resistance evaluation test results, and the rolling life test results. As the heat treatment conditions, the heating temperature was 1030 ° C. to 1120 ° C., and after cooling with nitrogen gas,
Immediately perform sub-zero treatment at -190 ° C for 30 minutes,
160-180 ° C × 2hr or 450-520 ° C ×
Tempering for 2 hours was performed. 160-180 ° C in the table
X-hr processing, A processing, 450
Those subjected to the treatment at ５520 ° C. × 2 hr are described as the B treatment.

The reason for setting the treatment temperature of the B treatment to 450 to 520 ° C. is that if tempering is performed at a temperature higher than that, agglomeration of the precipitated carbides and nitrides starts and softens, and the corrosion resistance rapidly decreases. is there.

The quality of heat treatment was evaluated for δ ferrite and eutectic carbide. Magnification × using an optical microscope
400 Observation of the visual field of 400 mm ² was observed. If the δ ferrite was observed, it is marked with a cross in the table. For the eutectic carbide, image processing was performed. Are extracted from the largest one, and the average value is described. If none of the circle equivalent diameters exceeds 3 μm is found, “none” is described.

The corrosion resistance evaluation test was performed by a salt spray test and pitting potential measurement. Salt spray test is based on JIS Z2
The test was performed using a 5% NaCl solution at a temperature of 35 ° C. in accordance with 371, and the test piece was evaluated by the appearance of the test piece after 150 hours. In Table 20, ◎ indicates that no rust was observed, and ○
Indicates that rusting was slightly observed, △ indicates that rusting occurred almost over the entire surface, and X indicates that rusting was remarkable. The pitting corrosion potential was measured in accordance with JIS G0577. First, a test piece polished up to No. 800 with abrasive paper was
Passivation treatment by immersion in a 0% HNO3 solution for 1 hour, followed by sweeping in a 3.5% NaCl solution at 30 ° C. at a potential sweep rate of 20 mV / min.
It was evaluated by mVvsSCE when it reached 00 μA / cm ² .

The life test was carried out using a thrust-type rolling life tester described on pages 10 to 21 of "Special Steel Handbook", 1st edition (edited by Denki Steel Research Institute, Rigakusha, May 25, 1969). The number of cumulative stress repetitions up to the time when flaking occurs in each sample (life)
And a Weibull plot was created, and each L10 life was determined and evaluated from the results of each Weibull distribution.

(Clean lubrication life test) Surface pressure: 4900 Mpa Rotation speed: 1000 rpm Lubrication oil: No. 68 turbine oil (Salt spray cycle life test) First, the JISZ23
A salt spray test was performed for 2 hours under the conditions in accordance with No. 71, and after thoroughly degreased with acetone, the above-mentioned clean lubrication life test was performed up to 1 × 107 cycles. The salt spray test was performed for 2 hours, and the test was repeated, and the life was defined as the cumulative number of repetitions up to the time when flaking occurred in each sample. The evaluation was performed by preparing a Weibull plot in the same manner as in the clean lubrication life test, and obtaining each L10 life from the results of each Weibull distribution.

According to Tables 19 and 20, the steel of the present invention is C
% ≦ −0.05Cr% + 1.41 prevents formation of coarse eutectic carbides, and further (eq1) = Cr% + Si% + 1.5Mo%, (eq2) = C% + 0.83N% + 0.12Mn% + 0.
05Ni% + 0.02Cu%, the mutual relationship between both sides (eq2) ≧ 0.04 × (eq1) −0.3
9 also prevents formation of δ ferrite, which is harmful to toughness and life, and pitting corrosion resistance index PI value = Cr
% + 3.3Mo% + 30N% -45C% is 10.0% or more, and furthermore, the total content of carbon and nitrogen is 0.4 or more, so that it has very high hardness and high corrosion resistance. Table 20
As is clear from the above, the steels of the present invention shown in 71 to 83 have extremely excellent corrosion resistance and a long life. In particular, in the salt spray cycle life test, the life of the conventional martensitic stainless steels of Reference Examples 84 and 85 was drastically reduced, whereas the steel of the present invention showed a long life.

Further, as described in 81 to 83, the steel of the present invention is used at a relatively high temperature because it undergoes secondary hardening without significantly impairing the corrosion resistance, and is used at a high temperature when dimensional stability is required. It is also usable enough.

Reference Examples 84 and 85 are conventional martensitic stainless steels, but have poor corrosion resistance due to high carbon content, and particularly have a very coarse eutectic carbide because 85 does not satisfy the formula. It has a short life. 86, 8
8, 93 to 100 satisfy the formulas and formulas,
Since the pitting corrosion index PI of the formula is not sufficiently secured, the corrosion resistance and the like are inferior to the steel of the present invention. 87, 89,
Since No. 90 did not satisfy the formula, coarse eutectic carbides were formed and the corrosion resistance, life, etc. were reduced. No. 91 and 101 did not satisfy the relationship, and δ ferrite was formed. In No. 92, the total content of carbon and nitrogen for solid solution strengthening of martensite was less than 0.4, the hardness was insufficient, and the life was shortened.

As described above, the present invention provides an extremely high corrosion resistance rolling martensitic stainless steel in which the corrosion resistance and life of the conventional stainless steel are greatly improved.

[0249]

[Table 19]

[0250]

[Table 20] <Example VIII> This example corresponds to the eighth embodiment.

Table 21 shows the alloy components of the test material and comparative steel used in this example.

The results of the heat treatment performed in the same manner as in Example VII and the results of the corrosion resistance evaluation test and the rolling life test are shown in Table 2.
It is shown in FIG.

The high-temperature life test was carried out in a deep groove ball bearing 620.
6 and under the following conditions.

(High temperature life test) Temperature: 170 ° C. P / C: 0.71 Lubrication: Jet oil ball: M50 From Tables 21 and 22, the steel V of the present invention has (1) C% ≦ −0.0.
By satisfying 5Cr% + 1.41, the formation of coarse eutectic carbides is prevented. (2) [eq1] = Cr% + Si% + 1.5Mo% + 3.5V
%, [Eq2] = C% + 0.83N% + 0.12Mn% + 0.05
(Ni + Co)% + 0.02Cu%, and their mutual relationship [eq2] ≧ 0.04 × [eq1] −0.3
9 and also satisfying [eq2] ≦ 0.8, the formation of δ ferrite which is harmful to toughness and life and the decrease in hardness due to the increase of retained austenite are prevented, and (3) PI value of pitting corrosion resistance index = Cr% + 3.3Mo% + 30N% -45C
% Is 10.0 or more, and furthermore, the total content of C and N is 0.4 or more, so that high hardness and high corrosion resistance are obtained. Also,
(4) Since Mo + V and Co + Ni are contained in an optimum composition, high-temperature life characteristics required for a bearing used at a relatively high temperature are excellent.

As is clear from Table 22, (C-1)
(C-12) (Examples 101 to 112) The steel of the present invention is an example of the present invention in the case of the B treatment, but the base is solid-solution strengthened with an alloy component of Co or Ni, and Mo or V, Cr
Secondary hardened by carbide, nitride, etc., good in corrosion resistance, life under corrosive environment, and high temperature life. Examples 113 and 114 are examples in the case of the A treatment, and are extremely good in corrosion resistance and life in a corrosive environment. However, the high temperature life test was a test at substantially the same temperature as the tempering temperature, and was not carried out because it was not preferable in view of dimensional changes and the like.

Reference Examples 115, 116, 122 to 127
Has a lower content of Co + Ni or Mo + V than the present invention and is inferior in high-temperature life. Reference Example 1
17, 119, 128, and 129 did not satisfy the relationship of the above (2), and δ ferrite was formed. Reference Examples 118 and 120 do not satisfy [eq2] ≦ 0.8 of the above (2), so that the retained austenite is stabilized, sufficient hardness cannot be obtained, and good life cannot be obtained. In Reference Example 121, C + N ≧ 0.4 in the above (3).
Is not satisfied, sufficient hardness is not obtained, and good life is not obtained. Reference Examples 122, 123, and 12
No. 6 did not satisfy the PI of the above (3) and was inferior in corrosion resistance to the examples. In particular, 126 has the above (1)
Is not satisfied, and corrosion resistance and life are remarkably reduced due to eutectic carbide formation. Reference example 125 is the same as P in (3) above.
Although it satisfies I, it does not satisfy (1), and the corrosion resistance and life are reduced due to the formation of eutectic carbide.

FIG. 6 is a diagram showing the correlation between the C content and the Cr content. Those which do not satisfy the above-mentioned relationship (1) are:
All show that a coarse eutectic carbide of 3 μm or more was formed. Since the steel V of the present invention satisfies the above relation (1), no eutectic carbide is generated as shown in FIG. Even if the relationship (1) is satisfied, eutectic carbides may be formed as an exception when nitrogen is not contained. In addition, if eutectic carbides are formed, induction hardenability is reduced, making it difficult to obtain a sufficient hardened layer depth, or causing unevenness in hardness due to penetration of the eutectic carbides. It is very important to satisfy the formula.

FIG. 7 is a diagram showing the correlation between eq1 and eq2, and the above (2) [eq2] ≧ 0.04 × [eq1] −0.39
Are not harmful to toughness.
This indicates that ferrite is formed. Since all the steels of the present invention satisfy this relational expression, this δ ferrite is not formed.

From the above, the above (1) and (2) [eq2]
It is a minimum requirement of the present invention to satisfy ≧ 0.04 × [eq1] −0.39.

Further, since stainless steel has remarkably poor machinability and cold workability as compared with low alloy steel, it is one of the features of the present invention to improve these properties. For this purpose, in addition to the conditions (1) and (2), 0.40 ≦ C + N ≦ 0.7,
It is necessary that eq1 ≦ 14.0 and eq2 ≦ 0.8. As shown in FIG. 8, when eq2 ≦ 0.8 is not satisfied, austenite is stabilized, and a large amount of retained austenite remains after quenching, and sufficient hardness cannot be obtained, which is particularly important.

Furthermore, one of the features of the present invention is that the corrosion resistance of the conventional martensitic stainless steel is remarkably improved. FIG. 9 shows the correlation between the PI value and the pitting potential, which is a relational expression found by the present inventors. As is clear from the figure, the pitting potential tends to increase as the PI value increases, and the PI value of the present invention ≧ 1
At 0.0, the corrosion resistance is much better. In addition, when a coarse eutectic carbide is contained, good corrosion resistance tends to be hardly obtained even if the PI value is large.

Further, the present invention is characterized in that the high-temperature life is increased when rolling fatigue occurs at a relatively high temperature. FIG. 10 shows the correlation between the content of Co + Ni or Mo + V and the high-temperature life, and is a relationship diagram found by the present inventors.

Co and Ni mainly strengthen the solid solution of the matrix, and Mo and V mainly precipitate finely in the matrix and strengthen the dispersion. C
This indicates that if the contents of o + Ni and Mo + V are too small, it is difficult to obtain a good high-temperature life.

As described above, the present invention provides a martensitic stainless steel for rolling which can be used for soaking for extremely high corrosion resistance, which is a significantly improved conventional stainless steel in particular in terms of corrosion resistance and life, and furthermore, high temperature life. Things.

[0265]

[Table 21]

[0266]

[Table 22]

[0267]

As described above, according to the present invention,
It is possible to provide an inexpensive rolling device with improved fretting resistance, acoustic performance, corrosion resistance, service life, and workability.

[Brief description of the drawings]

FIG. 1 is a front view of a fretting durability tester.

FIG. 2 is a schematic diagram showing a force applied to a ball bearing by a fretting durability tester by arrows.

3A and 3B are schematic diagrams of a surface damage type radial life test, wherein FIG. 3A is a plan view and FIG. 3B is a cross-sectional view taken along line aa ′.

FIG. 4 is a graph showing a change over time in acoustic performance in Example 5.

FIG. 5 shows an initial anderon value and 300 in Example 5.
It is a figure which shows the amount of change of the anderon value after time.

FIG. 6 is a diagram showing a correlation between a C content and a Cr content.

FIG. 7 is a diagram showing a correlation between eq1 and eq2.

FIG. 8 is a diagram illustrating a relationship between hardness (HRC) and eq2.

FIG. 9 is a diagram showing a correlation between a PI value and a pitting potential.

FIG. 10 is a diagram showing a correlation between the contents of Co + Ni and Mo + V and the high-temperature life.

[Explanation of symbols]

10: Preload spring, 12: Rotation stop, 14: Shaft, 16: Housing, 18a, 18b, 18c: Sleeve, 20:
Test bearing, 22: disc spring, 24: support bearing, 26:
AC servo motor

Claims (1)

[Claims] 1. An outer member, an inner member, and a plurality of rolling elements disposed therebetween, wherein the rolling elements include a first contact surface, which is a contact surface of the outer member with the rolling element, and a first contact surface. In a rolling device that rolls with respect to a second contact surface that is a contact surface of the inner member facing the rolling member with respect to the second member, at least one of the outer member, the inner member, and the rolling member is weight%. And C; 1.5
%; Cr: 10% to 20%; Mn: 0.1% to 0.8%; Si: 0.1% to 1.0%; N: 0.2
Rolling device made of alloy steel containing less than 10%.