JP4984272B2 - Steel with excellent vibration damping performance, method for producing the same, and damping body including the steel - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a steel having excellent vibration damping properties having high strength, excellent toughness, and excellent cold workability, a method for producing the same, and a vibration damping body including the steel.

Conventionally, materials having a function of reducing vibration and noise have been demanded in the fields of automobiles, precision equipment, electronic equipment, medical equipment, machine tools, transportation, and the like.
In response to this, materials having vibration damping ability include cast iron, Mn-Cu alloy, Mg-Zr alloy, Mg-Ni alloy, Al-Zn alloy, Fe-Al-Cr alloy, Ni-Ti alloy, Cu-Al -Ni alloys and the like are known.
Of these, cast iron and Mg-based alloys have the disadvantage of low strength.
Mn—Cu alloys have low strength and have the drawback that the damping capacity is extremely reduced at 100 ° C. or higher.
The Fe—Al—Cr alloy has a drawback that the damping capacity is reduced by strain.
These materials are relatively excellent in vibration damping capability, but contain a lot of expensive elements, which increases the price of alloy materials and limits industrial applications.

As materials that can be used at low temperatures in a liquefied gas atmosphere such as liquefied natural gas (boiling point: -164 ° C), liquid oxygen (boiling point: -183 ° C), liquid nitrogen (boiling point: -196 ° C), JIS SUS304, etc. An austenitic stainless steel or an aluminum alloy such as JIS 5000 series is used.
Here, steel materials used for transportation such as materials for linear motors are required to be steel with excellent vibration damping properties with new functions that absorb and reduce radiated sound due to environmental problems such as noise in addition to low temperature toughness. .
For automobiles, motorcycles, and the like, there is a demand for steel that is excellent in shock vibration absorption, low in cost, and excellent in vibration damping properties for collision safety.

  In order to solve the above problems, high-manganese steel in which nickel, which is an expensive element in nickel-based stainless steel, is replaced with manganese as a low-temperature material that does not use expensive nickel and aluminum is proposed. It is being studied as a material used in fusion reactors, superconducting motors and superconducting linear motors.

  In addition, for example, for tool supports or bolts and nuts, steel having excellent vibration damping properties that satisfy the conditions of high strength and high toughness, which are basic characteristics thereof, is required.

In order to solve the above problem, for example, according to Patent Document 3, a high-strength and high-damping capacity Fe—Cr—Mn alloy and a method for manufacturing the same are disclosed as materials having high mechanical strength and vibration damping capacity. ing. This patent includes a high-strength, high-damping capacity Fe-Cr-Mn alloy having a chromium mass percentage of 9-15%, a manganese mass percentage of 18-26%, the balance iron, and an epsilon-martensite phase of 40% or more and its A manufacturing method is disclosed. The Fe-Cr-Mn alloy is based on stainless steel in terms of composition, its mechanical properties are almost the same as stainless steel, and it has excellent vibration damping properties. It is an invention to be solved.

However, according to the technique disclosed in Patent Document 3, it is disclosed that the manganese mass percentage is 18 to 26%. However, when this material is melted, the manganese component easily evaporates, so Yield is poor, and manganese has the disadvantage of significantly increasing the refractory loss of refractories used in the melting of steel, so the cost of melting increases and the above industrial applications are extremely limited. There is a point. And when there are many manganese components, since material itself will become very hard, there exists a problem that cost occurs at the time of the crack generation at the time of hot processing, and cold processing.

On the other hand, as shown in Patent Document 2, the present inventors, as a material having vibration damping ability, have a carbon mass percentage of 0.05% or less, a manganese mass percentage of 13 to 18%, a chromium mass percentage of 9 to 15%, nickel, mass percentage from 0.01 to 6.0%, aluminum mass percentage from 0.01 to 0.05%, 0.01% nitrogen by weight percent or less, by cold working the material the balance being iron, austenite phase is the matrix (hereinafter High-strength and high-damping capacity Fe-Mn-, characterized in that an epsilon martensite phase (hereinafter referred to as "ε-Ms phase") is produced in a volume percentage of 10% or more. A Cr-Ni alloy is proposed.
However, in Patent Document 2, a high-strength and high-damping ability alloy is recommended by a method by cold working, but not only the vibration damping ability is not stably obtained, but also the toughness of the base material is significantly reduced. It has been found that there may be a problem that the applications described above are limited.

In patent document 2, manganese mass percentage 13-18% and manganese amount can be decreased by adding nickel mass percentage 0.01-6.0%.
Although this technique is a countermeasure technique for reducing the manufacturing cost by lowering the manganese component by adding nickel, it is a countermeasure for improving the cold workability by adding expensive nickel. From the viewpoint of raw material costs, it is rather a technology that increases costs, and it is necessary to return to the principle of the principle of total manufacturing costs and reexamine.

According to the technique disclosed in Patent Document 8, carbon mass percentage 0.01-0.25%, silicon mass percentage 0.01-0.5%, manganese mass percentage 15-40%, chromium mass percentage 0.5. With a main chemical composition of -10% as a patent requirement, a high manganese steel material excellent in properties such as low temperature toughness has been proposed by setting the volume percentage of the ε-Ms phase within a specific range.
However, since the manganese mass percentage in Patent Document 8 is as high as 15 to 40%, there is a problem in manufacturing technology because of high costs in hot working and cold working.
And patent document 8 is not related with the vibration damping expression of steel.

As a result of investigations to solve the above-mentioned problems, the present inventors have found that the stacking fault energy SFE (mJ / m ² ) (Formula 1, non-existence) indicating the degree to which the ε-Ms phase is easily generated by heat treatment or cold working. (See Patent Documents 1 and 2) (hereinafter referred to as “SFE”). While maintaining SFE at 20 mJ / m ² or less, the amount of manganese is obtained by partially replacing the effect of manganese by adding a small amount of silicon. As a result, it was found that the effect can be reduced.
[Formula 1]
SFE (mJ / m ² ) =
25.7 + 2 × [% Ni] + 410 × [% C] −0.9 × [% Cr]
−77 × [% N] −13 × [% Si] −1.2 × [% Mn] (1)

The present inventors have studied to meet the new demand for the development of damping steel having excellent damping properties while satisfying the conditions of high strength and high toughness. In order to obtain high strength steel without increasing the manufacturing cost, there is a method of increasing the carbon mass percentage. However, since carbon, particularly solute carbon, inhibits the vibrational absorption ability of the ε-Ms phase, the present inventors have consistently limited the carbon mass percentage to 0.10% or less.
Here, in order to obtain high strength, by adding a carbon mass percentage exceeding 0.10%, in order to obtain good toughness and good vibration control, heat treatment is performed at a temperature near 700 ° C. I devised a technique for reducing solid solution carbon by making carbon into the form of chromium carbide (see Non-Patent Document 3). When such heat treatment is performed, the solid solution carbon mass percentage is expressed by [% C ], and therefore, it is appropriate that the above-described Equation 1 is Equation 2.
Specific heat treatment conditions will be described in detail later.
That is,
[ Formula 2 ]
SFE (mJ / m ² ) = 25.7 + 2 × [% Ni] + 410 × [% C ] −0.9 × [% Cr] −77 × [% N] −13 × [% Si] −1.2 × [% Mn] (2)

The damping steel excellent in damping performance according to the present invention is characterized in that the stacking fault energy (SFE) (mJ / m ² ) calculated by the formula (2) satisfies the formula (3). To do.
The stacking fault energy (SFE) (mJ / m ² ) calculated by the mathematical formula (3) is a scale (index, Merckmar) indicating the degree of easy generation of the ε-Ms phase, and satisfies the mathematical formula (3). This means that vibration damping is excellent.
[Formula 3]
−20 (mJ / m ² ) ≦ SFE ≦ 20 (mJ / m ² ) (3)

The damping steel excellent in damping properties according to the present invention is that the volume percentage of the epsilon-martensite phase [% ε-Ms phase] measured by the X-ray diffraction method satisfies the formula (4). Features. The volume percentage [% ε-Ms phase] of the epsilon-martensite phase measured by the X-ray diffraction method is a scale (index, Merckmar) indicating the vibration damping property of the steel specified from the metal structure of the steel. Satisfying (4) means excellent vibration damping properties.
[Formula 4]
10% by volume ≦ [% ε-Ms phase] ≦ 50% by volume (4)

The damping steel excellent in damping performance according to the present invention is characterized in that a loss coefficient (η) representing damping performance measured by the cantilever method satisfies the formula (5).
The loss factor (η) representing the vibration damping property measured by the cantilever method is a scale (index, Merckmar) indicating the vibration damping property of steel, and satisfying Equation (5) Means excellent.
[Formula 5]
0.005 ≦ η ≦ 0.10 (5)

The vibration-damping steel excellent in vibration damping according to the present invention is a Charpy test (Charpy test) in an atmosphere of −196 ° C. in accordance with a test method specified in Japanese Industrial Standard (JIS Z 2242: 2005 Charpy impact test method for metal materials). test), an impact load was applied to the back of the notch of the test piece with a hammer under the conditions of a hammer weight W [N], a distance R [m] from the rotation axis center line to the center of gravity of the hammer, and a lifting angle α [deg]. Sometimes, Charpy absorbed energy vE−196 _{° C.} [J] of the test piece calculated from the subsequent swing angle β [deg] according to Expression (6) satisfies Expression (7).
[Formula 6]
vE-196 _{° C.} = W × R × (cos β-cos α) (6)
[Formula 7]
50 (J) ≦ vE-196 _{° C.} ≦ 280 (J) (7)

  The damping body according to the present invention includes steel balls, rolling bearings, bolts and nuts, cutting tool supports, HDD suspensions, leaf springs, coil springs, automobile exhaust pipes, automobile reinforcements, building seismic isolation supports, superconductivity It is applied to a body cooling refrigerant liquid container.

In [Table 1] and [Table 2], for the present invention, Patent Documents 1 to 7 and Non-Patent Document 1, a comparison table comparing the invention specific matters (configuration requirements of the invention) and the effects (effects) of the invention is shown. Indicated.
As shown in [Table 1] and [Table 2], the features of the invention-specific matters (constituent requirements of the invention) of the present invention are relative to the mass percentage of Si in comparison with Patent Documents 1 to 7 and Non-Patent Document 1. By setting the value to a high value, the mass percentage of Mn, Cr, and Ni can be set to a significantly low value.
As shown in [Table 1] and [Table 2], one of the features in the effect (effect) of the present invention is that the cold workability is remarkably improved by setting the mass percentage of Mn to a low value. It was possible.
As shown in [Table 1] and [Table 2], one of the features in the effect (effect) of the present invention is that the cold workability is remarkably improved by setting the mass percentage of Cr to a low value. It was possible.
As shown in [Table 1] and [Table 2], one of the features of the effect (action effect) of the present invention is that the cost can be significantly reduced by setting the mass percentage of Ni to 0. .

JP 2009-155719 A JP2007-32143A JP 2002-121651 A (Patent No. 3378565) JP 07-150300 A Japanese Patent Laid-Open No. 05-255813 Japanese Patent Laid-Open No. 04-232228 Japanese Patent Laid-Open No. 04-063243 JP 2007-126715 A JP 2010-090472 A

Ministry of Education, Culture, Sports, Science and Technology, report on the results of the joint research project for creating innovative research facilities, March 3, 2009, “Elucidation of the mechanism of vibration damping of stainless steel materials”, oral report by TK Techno Consulting Co., Ltd. Published on the Internet.) Pickering: Proc. Conf. Stainless Steels, Gothenburg, Sept. (1984) Hiroshi Arai: Iron and Steel, 56 (1970), No. 1, p. 44.

  The present invention, in the above-described technical background, can respond to vibration, noise reduction, collision safety requirements, can provide high strength and good toughness, vibration-damping steel excellent in damping properties, a method for producing the same, and It aims at providing the damping body comprised including this steel.

The inventors of the present invention have deeply considered the relationship between the vibration damping performance mechanism and the toughness development mechanism in the steel material having excellent vibration damping performance shown in Patent Document 9.
That is, the steel material having excellent vibration damping property acts as a vibration damping expression because the ε-Ms phase, which is a structure inside the steel material, effectively absorbs shock or continuous vibration applied from the outside. It is what.
Here, it can be considered that the vibration damping expression mechanism also leads to the toughness expression of the steel material.

FIG. 1 shows a transmission electron micrograph (hereinafter referred to as “TEM photograph”) of the steel material according to the present invention.
From FIG. 1, it can be considered that the fine structure of the ε-Ms phase generated by heat treatment or cold working expresses toughness by absorbing vibration due to external impact.

The TEM photograph of FIG. 2 shows the stacking fault dislocations in the γ-phase of the steel according to the present invention, and the aggregate of the stacking fault dislocations is the ε-Ms phase.
That is, it can be considered that the vibration of the stacking fault dislocation shown in FIG. 2 absorbs external vibration or impact energy.

Charpy absorbed energy (W ₀ ) representing the toughness of steel is the sum of impact fracture absorbed energy (W ₁ ) of the base metal itself and shock vibration absorbed energy (W ₂ ) due to the ε-Ms phase generated in the steel. (Formula 8).
That is,

[Formula 8]
W ₀ (J) = W ₁ (J) + W ₂ (J) (8)
In Equation (8), J is a unit of absorbed energy (joule).
Here, the impact vibration absorption energy (W ₂ ) can be expressed by Equation 9.
That is, the dislocation density (ρ) existing inside the specimen volume (V) of interest vibrates n times by a distance (Δ) due to an external impact, and only stacking fault energy (SFE) is consumed as vibration energy. Is done.

[Formula 9]
W ₂ (J) = V (m ³ ) · ρ (m / m ³ ) · Δ (m) · n (times) · SFE (J / m ² ) (9)

  Table 3 shows a semi-quantitative representation of the thought process that stacking fault dislocations absorb impact energy in the Charpy test.

When an impact is applied to the Charpy test piece shown in item (1) of Table 3, a vibration with a resonance frequency of 3 kHz calculated from the shape factor F shown in item (2) and a decay time of 0.003 seconds is generated. From this, it is calculated that this vibration occurs about 10 times from impact to destruction.
As shown in the section (3), the density ρ (m / m ³ ) of dislocations contributing to vibration is estimated to be about 10 ¹⁶ (m / m ³ ), and the total length L (m) of the transition is (5) It can be calculated as 5.5 × 10 ¹⁰ (m) as shown in the section.
Since this dislocation vibrates by the stacking fault width (Δ), the total area S (m ² ) of the vibration of the transition is 5.0 × 10 ³ (m ² ).
These numerical values shown in Table 3, namely, V: 5.5 × 10 ⁻⁶ (m ³ ) (Charpy specimen size, 10 × 10 × 55 mm), ρ: 10 ¹⁶ (m / m ³ ), Δ: 10 Substituting ⁻⁸ (m), n: 10 (times), and SFE: 20 (mJ / m ² ) into Expression (8) yields W ₂ : 110 (J).
It is theoretically calculated that the stacking fault dislocation in the ε-Ms phase existing inside the test piece contributes to the improvement of toughness by absorbing the impact vibration energy applied in the Charpy test by 110 (J). Can be guessed.
These are approximate values that semi-quantitatively show the process of thinking about the relationship between the vibration control mechanism and the toughness mechanism, which will be demonstrated later by experimental examples.

In Patent Documents 2 and 3, a method of generating an ε-Ms phase mainly by cold working is recommended in order to make the material exhibit damping properties.
For example, in the case of a spring material having damping properties, this is an optimum method because the spring property and damping properties are simultaneously realized by cold working. However, when cold working is performed, the toughness of the base material itself is impaired, and W ₁ in Formula 8 is lowered.
In order to realize the object of the present invention, after the heat-induced ε-Ms phase is generated by the heat treatment method shown in the present invention, that is, by rapid cooling, the desired mechanical properties can be obtained without impairing toughness as necessary. The present inventors have come up with the present invention that solves the above problems by a new manufacturing technique in which cold working is performed to obtain properties.

As described above, damping tools with high strength and high toughness are required for cutting tool supports (shanks) or bolts and nuts. For this purpose, there is a method of increasing the amount of carbon, but it is known that carbon in a solid solution state inhibits the effective vibration absorbing ability of the ε-Ms phase.
As a method for solving the above-described problems, the present invention proposes a technique that solves the problem by making solid solution carbon into chromium carbide by a specific heat treatment method.

The invention according to the present application is specified by the matters described in claims 1 to 7 of the claims.
[Claims]
[Claim 1]
Carbon mass percentage [% C] 0.001-0.10 [%],
The silicon mass percentage [% Si] is 0.10 to 3.0 [%],
Manganese mass percentage [% Mn] of 5.0-18.0 [%],
Chromium mass percentage [% Cr] 0.01-20.0 [%],
0.001 to 0.10 [%] of mass percentage [% Al] of aluminum,
The balance is steel containing iron and inevitable impurities ,
The stacking fault energy (SFE) (mJ / m ² ) calculated by Equation 1 satisfies Equation 3,
The volume percent [% ε-Ms phase] of the epsilon-martensite phase measured by X-ray diffraction satisfies Expression 4.
A damping steel characterized by having excellent toughness, excellent cold workability, and excellent damping properties.
[ Formula 1 ]
SFE (mJ / m ² ) = 25.7 + 2 × [% Ni] + 410 × [% C] −0.9 × [% Cr] −77 × [% N] −13 × [% Si] −1.2 × [% Mn] (1)
Here, [% Ni] in Formula 1 is a mass percentage [% Ni] of nickel, and [% N] is a mass percentage [% N] of nitrogen.
[Formula 3]
−20 (mJ / m ² ) ≦ SFE ≦ 20 (mJ / m ² ) (3)
[Formula 4]
10 [volume%] ≦ [ε-Ms phase] ≦ 50 [volume%] (4)
[Claim 2]
The mass percentage of carbon [% C] exceeds 0.10 to 0.20 [%],
The silicon mass percentage [% Si] is 0.10 to 3.0 [%],
Manganese mass percentage [% Mn] of 5.0-18.0 [%],
Chromium mass percentage [% Cr] 0.01-20.0 [%],
0.001 to 0.10 [%] of mass percentage [% Al] of aluminum,
The balance consists of iron and inevitable impurities and is subjected to heat treatment for precipitation of chromium carbide at 500 to 800 ° C. for 1 to 60 minutes,
The stacking fault energy (SFE) (mJ / m ² ) calculated by Equation 2 satisfies Equation 3,
The volume percent [% ε-Ms phase] of the epsilon-martensite phase measured by X-ray diffraction satisfies Expression 4.
A damping steel characterized by having high strength, excellent toughness, excellent cold workability, and excellent vibration damping.
[ Formula 2 ]
SFE (mJ / m ² ) = 25.7 + 2 × [% Ni] + 410 × [% C ] −0.9 × [% Cr] −77 × [% N] −13 × [% Si] −1.2 × [% Mn] (2)
Here, [% Ni] in Equation 2 is the mass percentage of nickel [% Ni], [% N] is the mass percentage of nitrogen [% N], and [% C ] is 500 to 800 ° C. The solid solution carbon mass percentage [% C ] of the heat-treated steel for chromium carbide precipitation for 1 to 60 minutes .
[Formula 3]
−20 (mJ / m ² ) ≦ SFE ≦ 20 (mJ / m ² ) (3)
[Formula 4]
10 [volume%] ≦ [ε-Ms phase] ≦ 50 [volume%] (4)
[Claim 3]
The damping steel according to any one of claims 1 to 2, wherein a loss coefficient (η) representing damping performance measured by a cantilever method satisfies Formula 5.
[Formula 5]
0.005 ≦ η ≦ 0.10 (5)
[Claim 4]
In accordance with a test method specified in Japanese Industrial Standard (JIS Z 2242: 2005 Charpy impact test method for metal materials), in a Charpy test at a test temperature of −196 ° C., a hammer weight W [N], a rotation center axis When the impact load is applied to the notch back surface of the test piece with a hammer under the condition of the distance R [m] from the center of gravity to the hammer center and the lifting angle α [deg], based on the subsequent swing angle β [deg] The Charpy absorbed energy vE _{−196 ° C.} [J], which is the energy absorbed by the test piece calculated by Equation 6 and is a measure of the low temperature toughness of the steel, satisfies Equation 7. Damping steel described in any one of 1 to 3.
[Formula 6]
vE-196 _{° C.} = W × R × (cos β-cos α) (6)
[Formula 7]
50 (J) ≦ vE−196 _{° C.} ≦ 280 (J) (7)
[Claim 5]
Carbon mass percentage [% C] is 0.001 to 0.20 [%],
The silicon mass percentage [% Si] is 0.10 to 3.0 [%],
Manganese mass percentage [% Mn] of 5.0-18.0 [%],
Chromium mass percentage [% Cr] 0.01-20.0 [%],
0.001 to 0.10 [%] of mass percentage [% Al] of aluminum,
Steel with the balance containing iron and inevitable impurities
As a first step, a step of heating at 950 to 1200 ° C. for 1 to 5 hours,
As a second step, a step of hot working at a finishing temperature of 750 to 950 ° C.,
As a third step, a cold working step,
As a fourth step, after a solution heat treatment at 800 to 1100 ° C. for 1 to 60 minutes, a temperature range from 500 ° C. to 20 ° C. is rapidly cooled at a cooling rate of 10 to 50 (° C./sec). ,
As a 5th process, when the mass percentage of carbon exceeds 0.10 and it is -0.20 [%], after heat-treating at 500-800 degreeC for 1 to 60 minutes, from 500 degreeC to 20 degreeC A step of rapidly cooling the temperature region at a cooling rate of 10 to 50 (° C./sec);
As a sixth step, the step of performing cold working with cooling or with a cold working rate of 1 to 30%,
The method for producing vibration-damping steel according to claim 1, comprising:
[Claim 6]
The carbon mass percentage [% C] is 0.10 to 0.20 [%],
The silicon mass percentage [% Si] is 0.10 to 3.0 [%],
Manganese mass percentage [% Mn] of 5.0-18.0 [%],
Chromium mass percentage [% Cr] 0.01-20.0 [%],
0.001 to 0.10 [%] of mass percentage [% Al] of aluminum,
Steel with the balance containing iron and inevitable impurities
As a first step, a step of heating at 950 to 1200 ° C. for 1 to 5 hours,
As a second step, a step of hot working at a finishing temperature of 750 to 950 ° C.,
As a third step, after a solution heat treatment at 800 to 1100 ° C. for 1 to 60 minutes, a temperature range from 500 ° C. to 20 ° C. is rapidly cooled at a cooling rate of 10 to 50 (° C./sec). ,
As a 4th process, when the mass percentage of carbon exceeds 0.10 and is ~ 0.20 [%], after heat-treating at 500-800 degreeC for 1 to 60 minutes, the temperature from 500 degreeC to 20 degreeC Rapidly cooling the region at a cooling rate of 10 to 50 (° C./sec);
As a fifth step, the step of performing cold working with cooling or with a cold working rate of 1 to 30%,
The method for producing vibration-damping steel according to claim 1, comprising:
[Claim 7]
Applicable to steel balls, rolling bearings, bolts / nuts, cutting tool supports, HDD suspensions, leaf springs, automobile exhausts, automobile reinforcements, building seismic isolation supports, superconducting refrigerant containers A damping body comprising the damping steel according to any one of claims 1 to 4 .

Steel excellent in vibration damping according to the present invention can meet the demands of vibration, noise reduction and collision safety, and has high shock absorption capability because it can increase strength or impart toughness. It is possible to provide a steel excellent in damping properties, a method for producing the same, and a damping body made of the steel.
Specifically, steel balls, rolling bearings, bolts and nuts, cutting tool supports, HDD suspensions, leaf springs, coil springs, automobile exhaust pipes, automobile reinforcements, automobile seats, building seismic isolation supports, superconductors The vibration damping body applied to the cooling refrigerant liquid container can be provided.
According to the present invention, it is possible to remarkably reduce the weight percentage of manganese, which is an essential element for producing steel having excellent vibration damping properties, and thus it is possible to significantly reduce the production cost. It is possible to provide a large amount of steel with excellent vibration damping properties at low cost.

Hereinafter, the vibration-damping steel according to the present invention, the manufacturing method thereof, and the vibration-damping body including the steel will be specifically described.
FIG. 3 shows a manufacturing process in the present invention.

In Claims 1 and 2 of the present invention, the mass percentage of silicon is 0.10 to 3.0%, and the mass percentage of manganese is 5.0 to 18.0 mass %.
This discloses that the amount of manganese can be kept low by adding a small amount of silicon while having good damping performance.
That is, in the matters described in claims 1 and 2, in the relational expression (Formulas 1 and 2 ) of the stacking fault energy SFE (mJ / m ² ) indicating the degree to which an ε-Ms phase is easily generated by heat treatment or cold working, Since the term of −1.2 × [% Mn] and the term of silicon is −13 × [% Si], silicon has an effect of lowering SFE about 10 times that of manganese. .
That is, in order to keep SFE at 20 mJ / m ² or less, the manganese mass percentage is suppressed to a small value of 5.0 to 18.0 mass % by adding a small amount of 0.10 to 3.0 mass % of silicon.
This is an extremely important invention for obtaining excellent cold workability in high manganese steel.
That is, if the manganese mass percentage is less than 5.0%, the vibration damping performance is insufficient, and if it is 18.0% or more, the cold workability deteriorates and the manufacturing cost increases. Preferably, the manganese mass percentage is 10.0 to 18.0 mass %.

Here, the reason why the stacking fault energy is set to 20 mJ / m ² or less is to make it easier to generate the ε-Ms phase by rapid cooling, and when this value exceeds 20 mJ / m ² , the generation of the ε-Ms phase is generated. Is insufficient, and is preferably 10 mJ / m ² or less.
Furthermore, it had the silicon is 0.10 mass% or more is because the silicon additive effect less than 0.10% by mass decreases, the material becomes too hard and the solid solution hardening of silicon exceeds 3.0 wt% Therefore, the silicon mass percentage is preferably 0.5 to 1.0 mass %.
With respect to manganese, if the manganese mass percentage is less than 5.0%, the vibration damping effect is small, and if it is 18.0% by mass or more, the cold workability becomes poor and the manufacturing cost increases.

In Claims 1 and 2 of the present invention, in addition to the above, the chromium mass percentage is 0.01 to 20.0 mass %.
This relates to the generation of the γ-phase which is the basis of the present invention.
FIG. 4 shows a phase diagram of the Fe—Cr—Mn—Ni steel.
Figure 4 As is apparent from, the chromium 2-phase austenite phase (.gamma.-phase) and ferrite phase (alpha-phase) is generated in a region of more than 20.0 wt%, chromium less 20.0 wt% Preferably, it is 15.0 mass % or less.
Regarding the lower limit of chromium, by setting the range satisfying the condition that the stacking fault energy SFE (mJ / m ² ) (Equation 1 or 2) is 20 (mJ / m ² ) or less, the synergistic effect of chromium and manganese A region where the ε-Ms phase is effectively generated can be widened.
Here, in comparison with Patent Document 2, the role of epsilon-Ms phase generation nickel silicon, because manganese and chromium plays effective, expensive nickel in terms of vibration damping property expression had disappeared necessarily Yes. That is, in the present invention, there is no need to intentionally add nickel unless there is a need other than the expression of vibration damping properties.

Claims 1 and 2 of the present invention disclose that the volume percentage of the ε-Ms phase measured by the X-ray diffraction method is 10 to 50% by volume.
This is a quantitative expression of the metal structure, that is, the ε-Ms phase, which is a necessary condition for the basic damping expression of the present invention, and the damping property and toughness become insufficient at 10% by volume or less. In addition, it has been found that when the volume exceeds 50% by volume, the ε-Ms phases are entangled with each other and the vibration damping characteristics are reduced.
Preferably, the volume percentage of the ε-Ms phase is 20 to 40% by volume.

In the second aspect of the present invention, the reason why the carbon content exceeds 0.10 to ˜0.20 mass% is to impart high strength and excellent vibration damping properties without increasing the manufacturing cost.
In this case, since the vibration absorption capacity is inhibited when carbon, particularly, solid solution carbon increases, a technique for reducing the solid solution carbon into a chromium carbide form by performing a specific heat treatment is disclosed. .
This technique will be described in detail below.
FIG. 5 shows the relationship between the total carbon mass percentage [% C] and the solute carbon mass percentage [% C ] when heat-treated at 500, 600 and 700 ° C.
That is, the amount of carbon exceeding the solid solubility limit at each temperature becomes a precipitate having a large shape as chromium carbide, and obstruction to the damping performance can be eliminated.
FIG. 6 is a temperature-time relationship diagram showing a region in which chromium carbide is precipitated.
As shown in FIG. 6, after rapid solution heat treatment at 800 to 1100 ° C., carbon is finely left in the grains, and then heat treated at 500 to 800 ° C. to precipitate chromium carbide in the crystal grains. Then, cool it down quickly.
FIG. 7 is a photomicrograph after chromium carbide precipitation treatment.
By rapid cooling as shown in FIG. 7-2, no precipitation of chromium carbide is observed at the grain boundaries.

Nitrogen, which has the same effect as carbon, is inevitably mixed at about 0.010 to 0.100% by mass from the atmosphere during melting and production, and the vibration damping capacity is reduced. By making the content of 001 to 0.10% by mass , the nitrogen in the steel is made into the form of inclusions with a large AlN, thereby obstructing the damping performance.
In other words, rising when aluminum is insufficient aluminum content required to bind less than 0.001 wt% and above of steel in nitrogen, the surface and inside of the steel by an excess of aluminum exceeds 0.10 mass% This is because there is a risk that alumina-based defects are likely to occur.

In the matter described in claim 3 of the present invention, it is disclosed that the loss coefficient (η) measured by the cantilever method is 0.005 to 0.10, which is a steel material having excellent vibration damping properties. As a basic condition.
Here, since the vibration damping capability of the steel material according to the present invention is highly dependent on vibration strain, the loss factor (η) measurement method needs to make the vibration strain about 10 ⁻⁴ or more. The cantilever method was selected.
In the measured value, if the loss factor (η) is less than 0.005, the vibration damping function as steel having excellent vibration damping properties becomes insufficient, and the steel is used in the production conditions for exceeding 0.10. This is because the mechanical properties of are not suitable for the above-described applications.

In the matter described in claim 4 of the present invention, it is disclosed that Charpy absorbed energy (vE-196 _{° C.} ) at _{−196 °} C. representing toughness defined by JIS is 50 to 280 Joules.
Here, the reason why the Charpy absorbed energy (vE-196 _{° C.} ) is set to 50 joules or more is that, if it is less than 50 joules, for example, the specifications for superconducting cooling liquid nitrogen are not satisfied.
The reason why it is set to 280 joules or less is that, in order to obtain a toughness value exceeding 280 joules, it is necessary to add an expensive element such as nickel, which unnecessarily increases the cost of steel.

In the matter described in claim 5 of the present invention, a steel having a chemical composition defined in claim 1 or 2,
As a first step, a step of heating at 950 to 1200 ° C. for 1 to 5 hours,
As a second step, a step of hot working at a finishing temperature of 750 to 950 ° C.,
As a third step, a cold working step,
As a fourth step, after a solution heat treatment at 800 to 1100 ° C. for 1 to 60 minutes, a temperature range from 500 ° C. to 20 ° C. is rapidly cooled at a cooling rate of 10 to 50 (° C./sec). ,
As a fifth step, after performing chromium carbide precipitation treatment at 500 to 800 ° C. for 1 to 60 minutes as necessary, the temperature range from 500 ° C. to 20 ° C. is cooled to 10 to 50 (° C./sec). Rapid cooling at a speed,
As a sixth step, if necessary, a step of performing cold working with a cold working rate of 1 to 30%,
Has proposed a method for producing steel with excellent vibration damping properties.
Here, in particular, the important steps in the present invention are the fourth step, the fifth step, and the sixth step.
The fourth step is a so-called solid solution heat treatment. The reason why the heat treatment temperature is set to 800 to 1100 ° C. is that cold work strain removal and austenitization become insufficient at temperatures below 800 ° C. This is because the expression of vibration becomes insufficient, and when it exceeds 1100 ° C., the austenite crystal grain size becomes coarse and the mechanical properties become poor.
The reason for rapid cooling in the fourth and fifth steps is to effectively generate a thermally induced ε-Ms phase in the phase transition from the γ-phase to the ε-Ms phase, and this is performed at 10 to 50 ° C. / Sec. This is because the generation of the ε-Ms phase becomes insufficient at a cooling rate of less than 10 ° C / sec.
In the sixth step, a manufacturing method is disclosed in which the steel is further subjected to cold working of 1 to 30% or less to increase the volume% of the ε-Ms phase or to increase the strength of the steel by cold working. .
This can be selected according to need in order to obtain vibration damping properties, mechanical properties, or hardness necessary for the application.
Here, the cold working rate is set to 1 to 30% because the volume% of the ε-Ms phase generated when the cold working rate exceeds 30% exceeds 50%. This is because the vibration damping property is deteriorated because the vibration of the Ms phase is inhibited.

  The matters described in claim 6 of the present invention describe the case of finishing to a desired shape only by hot rolling, and the technical idea is the same as in claim 5.

In the seventh aspect of the present invention, steel balls, rolling bearings, bolts and nuts, cutting tool supports, HDD suspensions, leaf springs, coil springs, automobile exhaust pipes, automobile reinforcements, automobile seats, building exemptions A damping body made of steel having excellent damping performance according to any one of claims 1 to 4, wherein the damping body is applied to a seismic support body and a refrigerant liquid container for cooling a superconductor. Yes.
Here, what should be noted when using the steel having excellent vibration damping properties according to the present invention is effective only when the shape of the steel material of the present invention is set to the primary resonance frequency according to the vibration environment to which the steel material is applied. The vibration absorbing effect can be exhibited. It is an extremely important invention element of the present invention to present an application guideline that enables effective vibration suppression in an application environment based on this index.
The description of the damping body applied individually will be described in detail in Experimental Example 4.

The present invention provides a steel having excellent vibration damping properties and a method for producing the same that can improve cold workability, suppress production costs, and provide high strength and good low temperature toughness. Depending on the purpose of use of the steel having excellent vibration damping properties, the present invention may be used in the case where it is necessary to impart properties other than vibration damping ability such as spring property, workability, high temperature oxidation resistance, corrosion resistance and magnetism. In addition to the chemical composition that is the basic requirement of the element, for example, elements such as Ni, Mo, Nb, V, Cu, Co, REM, Zr, B, or Ca can be appropriately added in terms of element symbols. It is within the scope of the present invention.
“REM” indicates rare earth elements in general.

Hereinafter, the present invention will be described by experimental examples.

[Experimental Example 1]
As Experimental Example 1, steel having the composition shown in Table 4 was melted.
Here, elements not described in Table 4 will be described. Nitrogen inevitably invades during melting and is in the range of 0.008 to 0.10%.
Both phosphorus (P) and sulfur (S) were made 0.01% or less.
Nickel (Ni) was not intentionally added except for SUS304.
This was heated at 1000 ° C. for 2 hours and hot worked at a finishing temperature of 850 ° C. to obtain a hot rolled steel sheet having a thickness of 10 mm.
This was heat-treated in a vacuum at 950 ° C. for 1 hour and rapidly cooled to obtain a 10 mm square × 50 mm Charpy test piece.
Further, half of the test materials were cold worked to a thickness of 1.0 mm, subjected to heat treatment in vacuum at 950 ° C. for 1 hour, and then rapidly cooled.
At this time, the cooling rate from 500 ° C. to room temperature was 20 ° C./second.
Further, as a chromium carbide precipitation treatment, heat treatment was performed at 700 ° C. for 30 minutes, and then rapidly cooled in water.
The stacking fault energy SFE (mJ / m ² ) of this material was calculated by Equation 2. As the solid solution carbon weight percentage [% C ] in the mathematical formula, the value read from the relationship of FIG. 5 described above was used.
The volume% of the ε-Ms phase in the steel was determined by the X-ray diffraction method.
Furthermore, the loss factor (η) was measured by the cantilever method.
The loss factor (η) is measured by fixing one end with a clamp and the size of the vibrating part is 1.0 mm thick x 50 mm wide x 100 mm long. The fixed part is impacted at an acceleration of 3 G (3 x 980 mm / s ² ). The loss factor (η) was determined by measuring the free decay time and vibration frequency. The vibration strain at this time was 10 ⁻⁴ level.
The cold workability was evaluated based on the cold rolling rate until the next heat treatment was required when the sample for the test was prototyped with the test rolling mill.
A specific method and result of the cold workability evaluation will be described in detail in Experimental Example 3.
In particular, in Table 4, Invention Example 14 and Comparative Example 9 are materials having the same chemical composition, but Invention Example 14 is a case where chromium carbide precipitation treatment is performed, and Comparative Example 9 does not. This is a comparison of the characteristics of each case.
This makes it possible to compare the effects of chromium carbide precipitation treatment in a relatively high region where the carbon weight percentage is 0.10 to 0.20%, which is employed for the purpose of high strength.
As comprehensive evaluation, it represented by the symbol of excellent ((double-circle)), favorable ((circle)), and improper (x).

Hereinafter, Table 4 will be described in detail.
Inventive Examples 1 to 14 are examples in which silicon is added in an amount of 0.5 to 1.0% by mass , which is within the recommended range of the present invention.
Here, the inventive examples 1 and 2 have an SFE value of 10 mJ / m ² or less, and the ε-Ms phase volume% is within the scope of the present invention, so that the loss factor (η), cold workability And the low temperature toughness is very good. In Example 3 of the present invention, since 0.6 % by mass of silicon was added, it was confirmed that even if the chromium content was 6.0% by mass, extremely good vibration damping properties were exhibited if the SFE conditions were satisfied.
Next, since Examples 3 to 14 of the present invention have an SFE value of 20 mJ / m ² or less and an ε-Ms phase volume% within the scope of the present invention, the loss factor (η) and toughness are good. In particular, with regard to chromium, good damping properties are also obtained at 7.0% by mass (Invention Examples 5, 7 and 9) or 5.0% by mass (Invention Example 12), which are ranges satisfying the SFE conditions. Expression was confirmed.
About Comparative Examples 1 and 2, although judged from the indicators of SFE, ε-Ms phase volume% and loss factor (η) is good (◯), the amount of manganese is 22.0 and 19.0 mass %. Since the material is hard and cannot be mass-produced from the viewpoint of cold workability, comprehensive evaluation is impossible. This will be described in detail in the section of Experimental Example 3.
In Comparative Example 3, the vibration damping property is poor because no silicon is added.
In Comparative Example 4, since the amount of silicon is excessive, the material is hard and the processing cost is high, so actual production cannot be performed.
In Comparative Example 5, since the amount of manganese is insufficient, the vibration damping performance is poor.
In Comparative Example 6, since the amount of chromium is excessive and the parent phase is a two-phase region of γ-phase and α-phase, the amount of ε-Ms phase generated is small, so the loss factor (η) is also low. It is enough.
In Comparative Example 7, since the Al necessary for fixing nitrogen in the AlN form is insufficient, the action of the ε-Ms phase is inhibited.
Since the carbon amount exceeds 0.20 mass %, the comparative example 8 is inferior in damping property and low temperature toughness.
Comparative Example 9 is an example in which the heat treatment for precipitation of chromium carbide was not performed, and excessive solute carbon hinders the vibration damping performance of the ε-Ms phase. That is, the effect of improving the vibration damping in the high carbon region by the chromium carbide precipitation treatment is remarkable by comparison with the examples of the present invention.
Comparative Example 10 is SUS304, which does not exhibit vibration damping properties, but is listed for comparison because it is a mass-produced material with excellent low-temperature toughness.

Further, described in detail by FIGS. 8, 9 and 10 a graph of Table 4.
FIG. 8 shows the relationship between SFE and ε-Ms phase volume%, but Comparative Example 6 is a case where the chromium composition ratio is 21 mass %, which is a two-phase region of γ-phase and α-phase. Therefore, since the amount of ε-Ms phase generated is small, the loss coefficient (η) is also insufficient.
FIG. 9 shows the relationship between the ε-Ms phase volume% and the loss factor (η), but in Comparative Example 7, nitrogen dissolved in a small amount due to an excessive amount of aluminum added has a loss factor (η). Since it is lowered, the relationship between the ε-Ms phase volume% and the loss factor (η) is deviated.
FIG. 10 shows the relationship between the manganese and silicon contents and the ε-Ms phase volume%. In contrast to the silicon-free additive of the comparative example, the present invention example contains 0.5 to 1.0 mass % of silicon. This shows that even if the amount of manganese is less than 18% by mass, the necessary region of ε-Ms phase can be increased, and the main effect of the present invention is shown.
As is clear from these, for example, Examples 1 to 14 of the present invention were confirmed to exhibit excellent vibration damping properties and excellent low-temperature toughness comparable to SUS304, thus demonstrating the validity of the present invention.
FIG. 11 shows, as a representative example of the present invention, vibration damping performance (loss factor (η)) mechanical properties, low temperature toughness (Charpy absorbed energy) and free vibration attenuation waveform of Invention Example 1 and Comparative Example 10 (SUS304). It is a comparison.

[Experiment 2]
Experimental Example 2 relates to claims 5 and 6 of the present invention.
That is, the present invention relates to production conditions for effectively generating an ε-Ms phase that expresses a loss factor (η) and obtaining steel having good low temperature toughness, and demonstrates the main requirements of the present invention. Is.
The material of Invention Example 1 listed in Table 4 was used.
This was heated at 1000 ° C. for 2 hours and hot worked at a work finishing temperature of 850 ° C. to obtain a 10 mm thick hot rolled steel sheet. This was subjected to solution heat treatment in vacuum at 800 ° C. × 1 hr, and then subjected to cooling and cold working under the conditions shown in Table 5. From these, a small Charpy test piece of 5 mm square × 500 mm was collected.
For the measurement of mechanical properties and loss factor (η), the 10 mm thick hot-rolled sheet was cold-rolled into a 1.0 mm-thick cold rolled sheet, and this was similarly treated at 800 ° C. × 1 hr. After performing solution heat treatment in vacuum, cooling and cold working were performed under the conditions shown in Table 5.
As cooling conditions, water cooling conditions were 20 ° C./second, and air cooling conditions were 0.06 ° C./second.
Table 5 shows the measurement results of these mechanical properties, damping properties (loss factor (η)) and low temperature toughness (vE-196 _{° C} ).
A steel having excellent vibration damping properties to which low temperature toughness is added is important for loss factor (η) and low temperature toughness (vE-196 _{° C.} ).
On the other hand, the loss factor (η) and the mechanical properties (spring property) are important for steel with excellent spring damping properties.

Table 5 will be described in detail.
Test No. 1-1 to 1-5 are cases of quenching in water after solution heat treatment at 800 ° C.
Test No. 2-1 to 2-5 are cases in which air cooling is performed after solution heat treatment at 800 ° C.
Test No. As shown in 1-1 and 1-2, a steel excellent in vibration damping and low temperature toughness is obtained when it is quenched in water after heat treatment at 800 ° C. or when light cold working of about 5% is added thereto. be able to.
Test No. 1-3 and 1-4 assume the case where tensile strength is required depending on the purpose of use, but the low-temperature toughness is naturally reduced by cold working, but the vibration damping property is excellent.
Thus, the manufacturing method which produces | generates a heat induction (epsilon) -Ms phase by quenching after heat processing can respond to various uses.
However, if cold working of about 35% is applied, the vibration damping performance is also degraded.
On the other hand, test no. In the case of 2-1 to 2-5, it is a case where it is gradually cooled after heat treatment at 800 ° C., but the expression of vibration damping properties is insufficient with the heat treatment or the degree of light processing applied, It is impossible to find a condition in which both the strength and the low temperature toughness are excellent.
This indicates that a steel having excellent vibration damping properties and low temperature toughness can be stably produced only by rapid cooling treatment.

[Experiment 3]
Experimental Example 3 relates to the evaluation of the cold workability of the steel excellent in vibration damping properties of the present invention.
Table 6 shows manganese (inventive example 1 (Mn: 16%), inventive example 8 (Mn: 8%), comparative example 1 (Mn: 22%) and comparative example 10 (Mn: 1%, SUS304). For steels with different Mn content, the number of intermediate heat treatments and the following heat treatment are required in cold rolling from 2.0 mm to about 0.03 mm thickness by a test rolling mill (4-high rolling mill with a work roll diameter of 85 mmφ). This is a measure of the cold rolling rate until it becomes.
In Invention Example 1 or 8, the number of intermediate heat treatments is 3 times from 2.0 mm to about 0.03 mm, and the average cold rolling ratio until the next intermediate heat treatment is 63 to 70%. This is confirmed to be equivalent to SUS304 (Comparative Example 10), and is a comprehensive evaluation that actual production is possible.
On the other hand, Comparative Example 1 (Mn: 22%) requires nine intermediate heat treatments, and the average cold rolling ratio until the next intermediate heat treatment is 35%. This clearly shows that practical use is hindered due to excessive cold working costs in actual production.

[Experimental Example 4]
In order for the steel according to the present invention to exhibit its damping performance effectively, it is necessary to make the primary resonance frequency of the damping body suitable for the vibration environment to be applied.
Therefore, the present inventors obtained the relationship between various dimensions of simple cross-sectional areas of foils, plates, and bars and the primary resonance frequency for the steel according to the present invention by experiments shown in FIG.
FIG. 10 is an example of a frequency response function for obtaining the primary resonance frequency.
The relationship between the primary resonance frequency fn and the shape factor F (hereinafter referred to as “shape factor F”) obtained from the cross-sectional area S (mm ² ) and the length L (mm) of the sample (vibrating part) according to Formula 8 Was determined by trial and error.
The results are shown in Table 7 and FIG.
Thereby, the relationship of the following empirical formula (Formula 9) was derived.
That is, it was found that fn = C × F.
However, the coefficient (C) in Formula 9 is applied only to the steel excellent in vibration damping according to the present invention, and must be measured separately for other materials.
Further, it was confirmed that the above relationship can be applied in a wide range of F from 0.0001 to 1.0.
In the steel having excellent vibration damping properties according to the present invention, the shape factor F is calculated by Expression 8, and the primary resonance frequency fn (Hz) is calculated by Expression 9.

[Formula 8]
F = S / L ² (8)
[Formula 9]
fn (Hz) = 1.0 × 10 ⁵ × F (9)

Table 8 is an example in which steel having excellent vibration damping properties according to the present invention is applied as a vibration damping body.
The shape factor F and the primary resonance frequency of the damping body at that time are also described.
Here, in the case of an application where the cross-sectional shape changes in a complicated cross-sectional shape or in the length direction, the apparent primary resonance frequency is measured by the most suitable experiment based on the technical idea of the present invention. The idea of the present invention can be applied.

Table 9 shows the vibration environment, the primary resonance frequency of the damping body, and the dimensional design concept of the damping body for obtaining the vibration environment when applying the steel having excellent damping properties to the damping body. The evaluation of the application result was described.
According to this, the steel having excellent vibration damping properties according to the present invention has a vibration amplitude necessary for effectively expressing vibration absorption by applying the above relationship in each application field, and has excellent vibration damping. It became clear that it demonstrated performance.

As is clear from the above description, the steel excellent in vibration damping according to the present invention can add toughness that can meet the demands of vibration and noise reduction and collision safety, and can absorb shock vibration. Can be provided, a method of manufacturing the same, and a damping body constituted by the steel.
Specific examples of damping bodies include steel balls, rolling bearings, ball screws, bolts and nuts, cutting tool supports, HDD suspensions, leaf springs, coil springs, automobile exhaust pipes, automobile reinforcements, automobile seats, building exemptions A seismic support, a superconducting coolant liquid container.
According to the present invention, it is possible to remarkably reduce the content of manganese, which is an essential element for producing steel with excellent vibration damping properties, and thus it is possible to significantly reduce production costs, Since it is possible to provide a large amount of steel with excellent vibration suppression at a low cost, it has a high industrial utility value.

  Transmission electron microscope (TEM) photograph of an example of the present invention   Transmission electron microscope (TEM) photograph of stacking fault dislocations   Steel manufacturing process with excellent vibration damping and toughness   Phase diagram of Fe-Mn-Cr-Ni steel Relationship between solid solution carbon mass percentage [% C ] and total carbon mass percentage [% C] after heat treatment to form chromium carbide   Method of heat treatment for producing chromium carbide   Microstructure showing the relationship between heat treatment conditions and chromium carbide   Diagram showing the relationship between stacking fault energy (SFE) and ε-Ms phase volume percentage (%)   The figure which showed the relationship between the volume percentage (%) of ε-Ms phase and the loss factor (η) Figure showing the relationship between manganese mass (%) and ε-Ms phase volume percentage (%)   The figure which shows the free vibration damping waveform, mechanical property, and Charpy absorbed energy of an example of the present invention and a comparative example   Experimental method for primary resonance frequency measurement   Frequency response function measurement example   Relationship between form factor F and primary resonance frequency

Claims (7)

Carbon mass percentage [% C] 0.001-0.10 [%],
The silicon mass percentage [% Si] is 0.10 to 3.0 [%],
Manganese mass percentage [% Mn] of 5.0-18.0 [%],
Chromium mass percentage [% Cr] 0.01-20.0 [%],
0.001 to 0.10 [%] of mass percentage [% Al] of aluminum,
The balance is steel consisting of iron and inevitable impurities ,
The stacking fault energy (SFE) (mJ / m ² ) calculated by Equation 1 satisfies Equation 3,
The volume percent [% ε-Ms phase] of the epsilon-martensite phase measured by X-ray diffraction satisfies Expression 4.
A damping steel characterized by having excellent toughness, excellent cold workability, and excellent damping properties.
[Formula 1]
SFE (mJ / m ² ) = 25.7 + 2 × [% Ni] + 410 × [% C] −0.9 × [% Cr] −77 × [% N] −13 × [% Si] −1.2 × [% Mn] (1)
Here, [% Ni] in Formula 1 is a mass percentage [% Ni] of nickel, and [% N] is a mass percentage [% N] of nitrogen.
[Formula 3]
−20 (mJ / m ² ) ≦ SFE ≦ 20 (mJ / m ² ) (3)
[Formula 4]
10 [volume%] ≦ [ε-Ms phase] ≦ 50 [volume%] (4) The mass percentage of carbon [% C] exceeds 0.10 to 0.20 [%],
The silicon mass percentage [% Si] is 0.10 to 3.0 [%],
Manganese mass percentage [% Mn] of 5.0-18.0 [%],
Chromium mass percentage [% Cr] 0.01-20.0 [%],
0.001 to 0.10 [%] of mass percentage [% Al] of aluminum,
The balance consists of iron and inevitable impurities and is subjected to heat treatment for precipitation of chromium carbide at 500 to 800 ° C. for 1 to 60 minutes,
The stacking fault energy (SFE) (mJ / m ² ) calculated by Equation 2 satisfies Equation 3,
The volume percent [% ε-Ms phase] of the epsilon-martensite phase measured by X-ray diffraction satisfies Expression 4.
A damping steel characterized by having high strength, excellent toughness, excellent cold workability, and excellent vibration damping.
[Formula 2]
SFE (mJ / m ² ) = 25.7 + 2 × [% Ni] + 410 × [% C ] −0.9 × [% Cr] −77 × [% N] −13 × [% Si] −1.2 × [% Mn] (2)
Here, [% Ni] in Formula 2 is the mass percentage of nickel [% Ni], [% N] is the mass percentage of nitrogen “% N”, and [% C ] is 500 to 800 ° C. The solid solution carbon mass percentage [% C ] of the heat-treated steel for chromium carbide precipitation for 1 to 60 minutes .
[Formula 3]
−20 (mJ / m ² ) ≦ SFE ≦ 20 (mJ / m ² ) (3)
[Formula 4]
10 [volume%] ≦ [ε-Ms phase] ≦ 50 [volume%] (4) The damping steel according to any one of claims 1 to 2, wherein a loss coefficient (η) representing damping performance measured by a cantilever method satisfies Formula 5.
[Formula 5]
0.005 ≦ η ≦ 0.10 (5) In accordance with a test method specified in Japanese Industrial Standard (JIS Z 2242: 2005 Charpy impact test method for metal materials), in a Charpy test at a test temperature of −196 ° C., a hammer weight W [N], a rotation center axis When the impact load is applied to the notch back surface of the test piece with a hammer under the condition of the distance R [m] from the center of gravity to the hammer center and the lifting angle α [deg], based on the subsequent swing angle β [deg] , The energy absorbed by the test piece calculated by Equation 6,
4. The damping steel according to claim 1, wherein Charpy absorbed energy vE _{196 ° C.} [J], which is a measure of low-temperature toughness of the steel, satisfies Expression 7. 7.
[Formula 6]
vE-196 _{° C.} = W × R × (cos β-cos α) (6)
[Formula 7]
50 (J) ≦ vE−196 _{° C.} ≦ 280 (J) (7) Carbon mass percentage [% C] is 0.001 to 0.20 [%],
The silicon mass percentage [% Si] is 0.10 to 3.0 [%],
Manganese mass percentage [% Mn] of 5.0-18.0 [%],
Chromium mass percentage [% Cr] 0.01-20.0 [%],
0.001 to 0.10 [%] of mass percentage [% Al] of aluminum,
Steel with the balance of iron and inevitable impurities
As a first step, a step of heating at 950 to 1200 ° C. for 1 to 5 hours,
As a second step, a step of hot working at a finishing temperature of 750 to 950 ° C.,
As a third step, a cold working step,
As a fourth step, after a solution heat treatment at 800 to 1100 ° C. for 1 to 60 minutes, a temperature range from 500 ° C. to 20 ° C. is rapidly cooled at a cooling rate of 10 to 50 (° C./sec). ,
As a 5th process, when the mass percentage of carbon exceeds 0.10 and it is -0.20 [%], after heat-treating at 500-800 degreeC for 1 to 60 minutes, from 500 degreeC to 20 degreeC A step of rapidly cooling the temperature region at a cooling rate of 10 to 50 (° C./sec);
As a sixth step, the step of performing cold working with cooling or with a cold working rate of 1 to 30%,
The method for producing vibration-damping steel according to claim 1, comprising: Carbon mass percentage [% C] is 0.001 to 0.20 [%],
The silicon mass percentage [% Si] is 0.10 to 3.0 [%],
Manganese mass percentage [% Mn] of 5.0-18.0 [%],
Chromium mass percentage [% Cr] 0.01-20.0 [%],
0.001 to 0.10 [%] of mass percentage [% Al] of aluminum,
Steel with the balance of iron and inevitable impurities
As a first step, a step of heating at 950 to 1200 ° C. for 1 to 5 hours,
As a second step, a step of hot working at a finishing temperature of 750 to 950 ° C.,
As a third step, after a solution heat treatment at 800 to 1100 ° C. for 1 to 60 minutes, a temperature range from 500 ° C. to 20 ° C. is rapidly cooled at a cooling rate of 10 to 50 (° C./sec). ,
As a 4th process, when the mass percentage of carbon exceeds 0.10 and is ~ 0.20 [%], after heat-treating at 500-800 degreeC for 1 to 60 minutes, the temperature from 500 degreeC to 20 degreeC Rapidly cooling the region at a cooling rate of 10 to 50 (° C./sec);
As a fifth step, the step of performing cold working with cooling or with a cold working rate of 1 to 30%,
The method for producing vibration-damping steel according to claim 1, comprising: Applicable to steel balls, rolling bearings, bolts / nuts, cutting tool supports, HDD suspensions, leaf springs, automobile exhausts, automobile reinforcements, building seismic isolation supports, superconducting refrigerant containers A damping body comprising the damping steel according to any one of claims 1 to 4 .

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