JP3425128B2 - Free cutting alloy material - Google Patents

Description

Detailed Description of the Invention

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BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a free-cutting alloy material suitable for use as a material for equipment or parts that require excellent free-cutting properties.

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2. Description of the Related Art Examples of Ni-containing alloys include austenite-containing stainless steel, (Fe, Ni) -based electromagnetic materials typified by permalloy and permine bar, and (Fe, Ni) -based heat-resistant alloys. Many of them are widely used as materials for various devices or parts due to their multi-dimensional characteristics. Therefore, although these alloys may usually require cutting, these alloys generally have a problem of poor machinability. Therefore, in order to improve productivity, S, Pb, Se
Alternatively, an alloy containing a machinability improving element such as Bi to improve the machinability is used. When better machinability is required, such as when precision finishing is performed, the content of the machinability improving element is increased and the above elements are not used alone. Often used in combination.

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Here, sulfur (S), which is one of the machinability improving elements, is often used as MnS. However, if too much is added, (Mn, Cr,
The hot workability or cold workability may be impaired by the excessive formation of Ni) S or the like, and the excellent properties as an alloy may be impaired, and the use thereof is limited.

An object of the present invention is to provide a free-cutting alloy material having excellent machinability while maintaining the characteristics of the alloy comparable to those of conventional alloys.

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[Means, actions and effects for solving the problems]

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(3) The content of Ti is WTi (mass%), Z
WTi + 0.52W, where r content is WZr (mass%)
Zr is 0.03 to 3.5 mass%: Ti and Zr form a (Ti, Zr) -based compound that plays a central role in the machinability improving effect in the free-cutting alloy material of the present invention. It is an essential constituent element. When WTi + 0.52WZr is less than 0.03% by mass, the amount of (Ti, Zr) -based compound formed is insufficient, and a sufficient machinability improving effect cannot be expected. On the other hand, when WTi + 0.52WZr is excessive, the machinability is also decreased. Therefore, WTi + 0.52W
Zr needs to be suppressed to 3.5 mass% or less. Ti and Z
The above effect when r is contained in the alloy is approximately T
It is determined according to the total number of atoms (or the number of mols) contained regardless of the types of i and Zr. Since the atomic weight ratio of Zr and Ti is approximately 1: 0.52, titanium having a smaller atomic weight can exert a greater effect with a smaller mass. It can be said that WTi + 0.52WZr is a composition parameter that reflects the total number of atoms of Zr and Ti.

[0014]

Next, the free-cutting alloy material of the present invention can be specifically austenite-containing stainless steel. Austenite-containing stainless steel is often used in the form of shafts, for example, in industrial equipment, OA equipment, pumps, marine engines, etc., but its application is not limited to this. In any case, by applying the present invention, the machinability of stainless steel is significantly improved, and the manufacturing efficiency of various stainless steel parts or members can be dramatically improved.

Here, the austenite-containing stainless steel refers to stainless steel containing Fe as a main component and an austenite phase in the structure. Corresponding steel types shown in JIS: G4304 are exemplified below, but Ti, Zr, which is a characteristic part of the present invention,
As for S and Se, of course, there is no composition label in the standard. In this case, it means a steel material in which a part of Fe is replaced by the above element within the above composition range. Therefore, although reference is made to the standard numbers, all of them mean alloys unique to the present invention, which are based on alloys having compositions specified in the standards. Austenitic stainless steel: SUS20, which is a stainless steel that exhibits an austenitic structure even at room temperature.
1, SUS202, SUS301, SUS301J, S
US302, SUS302B, SUS304, SUS3
04N1, SUS304N2, SUS305, SUS3
09S, SUS310S, SUS316, SUS316
N, SUS316J1, SUS317, SUS317J
1, SUS321, SUS347, SUSXM15J
1, SUS836L, SUS890L, etc. can be illustrated. Austenite-ferrite stainless steel: Stainless steel showing a two-phase structure of austenite and ferrite, and SUS329J4L and the like can be exemplified. Precipitation hardening stainless steel: A stainless steel that can be added with an element such as aluminum or copper to precipitate a compound having these elements as a main component by heat treatment and hardened. SUS630, SUS631
Etc. can be illustrated. Further, the "stainless steel" referred to in the present invention
The heat resistant steels exemplified below are also included in the concept of. Austenitic heat resistant steels, for example, JIS: G4311 and G4312, whose composition is specified, include SUS31, SUH35, SUH3.
6, SUH37, SUH38, SUH309, SUH3
10, SUH330, SUH660, SUH661, etc. can be illustrated.

The conventional austenite-containing stainless steel containing S as a machinability improving element is exposed to the atmosphere to release the sulfur component contained in the stainless steel as a sulfur-containing gas. In some cases, sulfur contamination was caused around the parts. Therefore, suppression of release of the sulfur-containing gas (hereinafter, referred to as “improvement in outgas resistance” and the like) is also required.

Therefore, the free-cutting alloy material of the present invention is more than 2
50 mass% Ni, 12-50 mass% Cr, 5
In an alloy containing 86.95 mass% Fe,
It contains 0.01 to 0.4% by mass of C and has a Ti content of
Let WTi (mass%) and Zr content be WZr (mass%)
And WTi + 0.52WZr is 0.03 to 3.5% by mass.
To contain at least one of Ti and Zr
0.01 to 1 mass% S and 0.01 to 0.8 mass
% Se and / or Ti, Z and
The total content of r is 1. of the total content of S, Se and Te.
55 times or more, and at least Ti and Zr
Contains any of them as a metal element component, and
As a binding component of, C as an essential component, and further S
Less than one or two or more selected from Se or Te
At least a (Ti, Zr) -based compound formed in the tissue
The (Ti, Zr) -based compound has the composition formula (Ti,
_{Zr) 4 (S, Se,} Te) is expressed by 2 _{C 2} compound
Austenite-containing stainless steel containing at least
It is configured as.

Furthermore, the free-cutting alloy material constituted as the stainless steel according to the present invention is used as an alloy material test piece in a vertical direction of 15
mm, width 25 mm, thickness 3 mm, and a rectangular parallelepiped shape, the whole surface of which was polished using a # 400 emery paper, and a vertical direction of 10 as a sulfur component getter was prepared.
mm, width 5 mm, thickness 0.1 mm, silver foil having a purity of 99.9% or more, and 0.5 cc of pure water were sealed in a container having an internal volume of 250 cc together with the test piece, and the temperature inside the container was 8
After the temperature was raised to 5 ° C. and kept for 20 hours, when the sulfur component content WSO in the silver foil was analyzed, the value of WSO was 0.035 mass% or less. It can be a cutting alloy material.

For example, in order to maintain the characteristics as austenite-containing stainless steel, the above Fe, Ni, C are used.
It is a necessary condition to contain a necessary amount of essential components such as r for austenite-containing stainless steel. On the other hand, by adding S and Se in the above range to this austenite-containing stainless steel, it is possible to form a (Ti, Zr) -based compound effective in improving machinability. Due to the formation of such a compound, (Mn, C
It is possible to prevent or suppress the formation of a compound such as r, Ni) S, which is likely to cause deterioration of hot workability, and maintain good corrosion resistance and hot workability as stainless steel. Then, due to the formation of the (Ti, Zr) -based compound, the added S is contained as a part of the constituent elements of the (Ti, Zr) -based compound, and the amount of S existing dispersively in the matrix phase is reduced. Therefore, the sulfur-containing gas generated from the stainless steel can be suppressed.

In the present invention, when the above outgas resistance test is conducted, the silver foil is absorbed as a getter by a sulfur component released from the test piece as a sulfur-containing gas,
The sulfur content WSO in the silver foil is measured to quantify the outgas resistance of the material. Then, the measured WSO is specified to be 0.035 mass% or less. As described above, the stainless steel of the present invention whose outgas resistance is regulated has a small amount of the S component released when exposed to the atmosphere, and is unlikely to cause sulfur contamination in the surroundings. It can be suitably used for industrial equipment that requires high properties.

The factor that determines the outgas resistance of the material is mainly the material composition, but the sulfur component dissolved in the matrix phase constituting the stainless steel tends to collect at the grain boundaries. Therefore, in order to improve the outgas resistance, it is also effective to control the amount of crystal grain boundaries that tend to serve as a diffusion path when releasing a sulfur component, and thus the average crystal grain size and crystal grain morphology of the material. For example, the average value of the crystal grain size of the Fe-based phase (represented by the maximum distance between the circumscribed parallel lines when the circumscribed parallel lines are drawn while changing the position of the crystal grain observed in the microstructure cross section) Is preferably 100 μm or less.

The reasons for limiting the preferred content range of each component when the present invention is applied to austenite-containing stainless steel will be described below. (5) Ni: 2 to 50 mass% Ni must be contained at least 2 mass% in order to stabilize the austenite phase in stainless steel. Further, Ni is often added because it is effective in improving the corrosion resistance, particularly the corrosion resistance in a reducing acid environment, but from the viewpoint of imparting the corrosion resistance, it is preferable to contain Ni in an amount of 2% by mass or more. If you want to obtain non-magnetism, Cr, M
In relation to the amount of other components such as o, it is necessary to add the necessary amount of Ni so that the austenite phase becomes more stable and the alloy becomes austenite-containing stainless steel. In this case, the Schaeffler phase diagram shown in FIG. 3 can be used to determine the Ni content. This is because the austenite forming element and the ferrite forming element are Ni and
It shows the relationship with the organization by converting it as the equivalent amount of Cr amount and Cr amount (Source: Revised 5th edition Metal Handbook (Maruzen: 199)
0 years), p. 578). However, it is necessary to determine the necessary amount in consideration of excluding the amount of the Ti and / or Zr-based compound present from the constituent elements of the matrix phase. It should be noted that excessive addition of Ni leads to an increase in cost and may lead to deterioration of characteristics as stainless steel, so the Ni content is limited to 50 mass% or less.

(6) Cr: 12 to 50 mass% Cr is an essential element for ensuring the corrosion resistance of stainless steel. Therefore, 12 mass% or more is contained. Cr
If the content is less than 12% by mass, the corrosion resistance as stainless steel cannot be ensured due to intergranular corrosion due to sensitization. On the other hand, if added excessively, the formation of a compound such as CrS may impair the hot workability and lead to a decrease in toughness. There is also a problem that high temperature brittleness becomes remarkable due to excessive addition. Therefore, Cr is 5
It is contained in the range of 0 mass% or less. From the above, the content of Cr is preferably set in the range of 12 to 50% by mass, and if it deviates from the above content range, the characteristics as stainless steel may be deteriorated. Also, preferably 15 to
It is preferable to set it in the range of 30% by mass, and more preferably set in the range of 17 to 25% by mass.

(7) Fe: 5 to 85.95 mass% Fe is an essential component for constituting stainless steel. Therefore, 5 mass% or more is contained. Content is 5
If it is less than mass%, the strength as stainless steel cannot be obtained, which is not preferable. In addition, in relation to other components, 85.
It is impossible to contain more than 95% by mass. Therefore, the Fe content is in the range of 5 to 85.95 mass%. The Fe content is preferably 15 to
It is preferable to set in the range of 75% by mass, and more preferably in the range of 40 to 65% by mass.

(8) C: 0.01 to 0.4 mass% C is an essential component for improving the machinability, and at least 0.01 for obtaining the effect of improving the machinability. Contains more than mass%. By containing C (Ti, Zr)
Although a type compound is formed, it is considered that the machinability of the stainless steel is improved by forming the (Ti, Zr) type compound. If the content is less than 0.01% by mass, the formation of the (Ti, Zr) -based compound will be insufficient and the effect of improving the machinability cannot be obtained sufficiently. On the other hand, if it exceeds 0.4% by mass, carbides that are not effective for improving the machinability are excessively formed, and conversely the machinability deteriorates. In addition, the remaining C, which is not contained as a constituent element in the (Ti, Zr) -based compound that contributes to the improvement of machinability, forms a solid solution in the matrix phase of stainless steel, and also has the effect of improving the hardness of stainless steel. It is thought that. Therefore, the content of C is added according to the amount of the constituent elements of the compound that improves the machinability such as the (Ti, Zr) -based compound so that the machinability improving effect is exhibited in the best condition. At the same time, it may be appropriately set in consideration of the fact that the residual C solid-dissolved in the matrix phase exerts the effect of improving the hardness. In consideration of these matters, the C content is preferably set in the range of 0.03 to 0.3% by mass, and more preferably set in the range of 0.05 to 0.25% by mass. Is good.

(9) 0.01 to 1% by mass of S and 0.0
At least one of 1 to 0.8% by mass of Se: By containing S and / or Se, a (Ti, Zr) -based compound effective in improving machinability (for example, the composition formula (T
i, Zr) ₄ (S, Se) ₂ C ₂ ) is formed. Therefore, 0.01 mass% or more of both S and Se is contained so that this machinability improving effect can be obtained in stainless steel. However, excessive addition of these S and Se deteriorates the hot workability, which is not preferable. Further, if it is limited to S, the excessive addition of S will cause the residual S, which is not contained as a constituent element of the (Ti, Zr) -based compound, to be excessively dispersed in the matrix phase of the stainless steel, resulting in outgas resistance. Will also decrease. Therefore, in consideration of these matters, the contents of S and Se are set with the upper limit being 1% by mass for S and 0.8% by mass for Se. In addition,
In order to optimize the hot workability, machinability and outgas resistance of stainless steel, the contents of S and Se are preferably 0.01 to 0.7 mass% and 0.
It is preferable to set in the range of 01 to 0.5% by mass, and more desirably 0.01 to 0.5% by mass and 0.01% by mass, respectively.
It is preferable to set in the range of 0.4 mass%.

By adopting the composition as described above, it becomes possible to obtain an austenite-containing stainless steel excellent in free-cutting property while maintaining corrosion resistance and hot workability and also having good outgas resistance. Further, in the free-cutting alloy material of the present invention constituted as stainless steel, the following respective components may be contained in the following composition ranges in order to make the characteristics more excellent. That is, at least one element of Si: 4 mass% or less, Mn: 4 mass% or less, P: 0.05 mass% or less, O: 0.03 mass% or less, N: 0.05 mass% or less. Can be included. The reason for the limitation will be described below.

(10) Si: 4% by mass or less Si can be added as a deoxidizing agent for steel. However, if the content is too large, the hardness after solution heat treatment becomes hard, which is not only disadvantageous in cold workability, but also increases the amount of δ-ferrite phase formed in stainless steel, which causes hot working of steel. In order to deteriorate the property, the upper limit is 4% by mass.
When the cold workability and the hot workability are particularly important, the amount is preferably set to 1% by mass or less, more preferably 0.5% by mass or less.

(11) Mn: 4% by mass or less Mn acts as a deoxidizing agent for steel, has the effect of suppressing the formation of the δ-ferrite phase, and also has the effect of stabilizing the austenite phase. Further, since a compound effective for machinability is produced by coexistence with S and Se, it may be added when machinability is particularly important. When the effect of improving the machinability is expected to be more remarkable, the content is preferably set to 0.6% by mass or more. However,
On the other hand, if Mn is contained, MnS is likely to be formed. Since MnS significantly deteriorates corrosion resistance and also deteriorates cold workability, it is preferable that MnS is not formed. Therefore, the Mn content is limited within the range of 4 mass% or less.
In addition, when the corrosion resistance and the cold workability are particularly important, 1
It is desirable to limit the content to mass% or less. More preferably, it should be limited to 0.5 mass% or less.

(12) P: 0.05% by mass or less P may segregate at the grain boundaries to increase the susceptibility to intergranular corrosion and may lead to a decrease in toughness. Therefore, the content of P should be kept as low as possible. , 0.05 mass% or less is preferable. Further, it is more desirable to suppress the content to 0.03 mass% or less, but reducing the content more than necessary may cause an increase in manufacturing cost.

(15) O: 0.03% by mass or less O is combined with Ti and Zr, which are the constituent elements of the (Ti, Zr) -based compound effective for improving the machinability, and oxidizes them. May form an object. Since these oxides are not effective in improving machinability, the O content should be suppressed as low as possible so as not to form these oxides. Therefore, the O content is preferably set to 0.03 mass% or less. Although it is a tradeoff with the manufacturing cost, it is preferably 0.01% by mass or less.

(16) N: 0.05% by mass or less N is not effective in improving the machinability because it combines with Ti and Zr which are the constituent elements of the compound effective for improving the machinability. Since it forms a nitride, it should be suppressed as low as possible. However, since it is an element usually contained in iron and steel, the upper limit is 0.05% by mass. In addition, it is preferably 0.03% by mass, though it is a balance with the manufacturing cost.
The amount is preferably below, and more preferably 0.01% by mass or less.

Next, the free-cutting alloy material of the present invention constituted as stainless steel may contain at least one of Cu: 4 mass% or less and Co: 4 mass% or less. (17) Cu: 4% by mass or less Cu is effective in improving corrosion resistance, particularly in a reducing acid environment, and also reduces work hardening ability to improve moldability. Further, the antibacterial property can also be improved by subjecting it to heat treatment or the like, so that it may be added if necessary. However, if added excessively, the hot workability deteriorates, so it is preferable to set the content in the range of 4% by mass or less. 1 when the hot workability is especially important
It is more desirable to control the content to be not more than mass%.

(18) Co: 4% by mass or less Co is an element effective for improving corrosion resistance, especially in a reducing acid environment, and is also effective for ensuring non-magnetism. You may add as needed. In order to obtain a more remarkable effect, it is preferable to contain 1% by mass or more. However, if added in excess,
Since it causes an increase in the source material cost, it is preferable to set it in the range of 4% by mass or less. When the raw material cost is particularly emphasized, it is more desirable to suppress it to 0.3% by mass or less.

Next, the free-cutting alloy material of the present invention constituted as stainless steel contains 0.1 to 10 mass% of Mo.
At least one of W of 0.1 to 10% by mass can be contained. The addition of Mo and W makes it possible to improve the corrosion resistance for strengthening the passive state and the hardness for the secondary hardening. In order to clearly obtain such an effect, it is preferable to add 0.1% by mass or more of both Mo and W. On the other hand, if added excessively, the hot workability is deteriorated, so it is preferable to set both Mo and W to 10 mass% as the upper limits.

If necessary, one or more selected from 0.01 to 0.2% by mass of Bi and 0.01 to 0.3% by mass of Pb may be contained. By containing these elements, the machinability of stainless steel can be further improved. At this time, in order to clearly obtain the effect of improving the machinability, it is preferable to contain Bi in an amount of 0.01% by mass or more and Pb in an amount of 0.01% by mass or more. On the other hand, if the addition amount is excessive, hot workability may be deteriorated. Therefore, the upper limit of Bi is preferably 0.2% by mass and the upper limit of Pb is preferably 0.3% by mass.

The free-cutting alloy material of the present invention constituted as stainless steel is Ca, Mg, B, REM (where REM is one or two of metal elements classified as Group 3A in the Periodic Table of the Elements). One or more selected from the above can be contained in a total amount of 0.0005 to 0.01% by mass. These elements are effective in improving the hot workability of steel. The effect of improving the hot workability obtained by adding these is that the total content is 0.00
When it is 05 mass% or more, it is more remarkably exhibited. On the other hand, if added excessively, the effect is saturated and conversely the hot workability is deteriorated. Therefore, the upper limit of the total content is set to 0.01% by mass. It should be noted that it is easy to handle as the REM mainly an element having low radioactivity, and from this viewpoint, Sc, Y, La, Ce, Pr, Nd,
Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Y
It is effective to use one or more selected from b and Lu. In particular, it is desirable to use a light rare earth element, particularly La or Ce, from the viewpoints of more prominently exhibiting the above effect and cost. However, a trace amount of radioactive rare earth elements (for example, Th
, U, etc.) may be contained. Further, from the viewpoint of cost reduction of raw materials, non-separated rare earths such as misch metal and didymium can also be used.

Further, the free-cutting alloy material of the present invention constituted as stainless steel contains 0.01 to 0.5 mass% of one or more selected from Nb, V, Ta, and Hf. be able to. Nb, V, Ta, and Hf
Has the effect of forming carbonitrides to refine the steel crystal grains and increasing the toughness, so that they can be added in a range of up to 0.5 mass%. In order to clarify the effect of enhancing the toughness, it is desirable to contain 0.01% by mass or more.

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EXAMPLES The following experiments were conducted to confirm the effects of the present invention. Example 1 First, a free-cutting alloy material of the present invention constituted as austenite-containing stainless steel was produced by the method described below. Each 5 added to the component composition (mass%) shown in Table 1.
A 0 kg steel ingot was melted in a high-frequency induction furnace.
It was heated to 0 to 1100 ° C. and hot forged into a 20 mm round bar. Steel grade code No. Steel types corresponding to the alloys of the present invention are Nos. 1 to 18 and 22 to 26.
19-21 and 27-29 are comparative alloys. Steel grade code No. 19 is SUS304, steel type code No. 20 is S
US303, steel type code No. 27 is SUS329J4L
It corresponds to each. Of these, the steel type code No. 1
Nos. 21 to 21 are steel grade symbols for the purpose of non-magnetism. 22-2
No. 9 is a steel grade group that is not intended to be non-magnetic. Of these, 1 to 24 and No. No. 27 was heated at 1050 ° C. for 1 hour and then water-cooled. Other steel types were heated at 750 ° C. for 1 hour, water-cooled, further heated at 650 ° C. for 2 hours, and then water-cooled, and then subjected to each test. All of the obtained inventive alloys had at least an austenite phase in the main phase. Table 1 shows the main phases of the alloy of the present invention. A, F, and M represent an austenite phase, a ferrite phase, and a martensite phase, respectively.

[0055]

[Table 1]

The main inclusions of the steel of the present invention are (Ti, Zr) ₄
Although it was (S, Se) ₂ C ₂ , some inclusions such as (Ti, Zr) S and (Ti, Zr) S ₃ were also recognized. In addition, Nos. 9, 10, and 13 having a high Mn content include
A small amount of (Mn, Cr) S was recognized. In addition,
The method of identifying each inclusion is as follows.
That is, an appropriate amount of the test piece is taken out from each round bar, and a methanol solution containing tetramethylammonium chloride and 10% acetylacetone is used as an electrolyte to electrolyze the metal matrix portion. Then, the insoluble compound contained in the steel is extracted by filtering the dissolved electrolytic solution and dried, and then this is ED.
The compound is identified from the appearance peak of the diffraction profile by analyzing with X. The composition of the compound particles in the steel structure was separately analyzed by EDX, and it was confirmed from the two-dimensional mapping that a compound having a composition corresponding to the compound observed in the EDX analysis was formed. There is. FIG. 1 shows the alloy No. 1 of the present invention. EDX of inclusions in 2
Shows the analysis results (both upper and lower) of (Ti, Z
It can be confirmed that the r) compound is formed as an inclusion. In addition, FIG. It is an optical microscope observation image (magnification: 400 times) of the steel surface of No. 2.

The following experiments were conducted for each of the above test products. 1. Hot workability test: The hot workability was evaluated by visually observing whether defects such as cracks occurred during hot forging. “○” indicates that virtually no defects were generated by the hot forging process, “x” indicates that a large crack was confirmed by the hot forging process, and “△” indicates by the grinder by the hot forging process. It shows that there are slight scratches that can be scraped.

2. Machinability evaluation: Machinability is evaluated by cutting resistance during machining, finished surface roughness, and chip shape. Cermet is used as the cutting tool, and the peripheral speed is 120m /
The cutting was performed under a water-soluble oil lubrication environment with min, the cut amount per revolution was 0.1 mm, and the feed amount per revolution was 0.05 mm. The cutting resistance is a measurement of the main component force generated in the tool during processing (unit: N). The finished surface roughness is the arithmetic average roughness (Ra: μm) of the surface of the test material after processing measured by the method specified in JIS-B0601.
Is. Further, by visually observing the shape of the chips, those having good crushability are shown as "good", and those having poor crushability and having chips connected are shown as "poor".

3. Outgas resistance evaluation: Outgas resistance was evaluated by defining the amount of S generated.
Specifically, the dimensions are 15 mm in length, 25 mm in width, and 3 mm in thickness, and the entire surface is # 400.
The test piece polished by the emery paper is used. Then, in a closed container having a volume of 250 cc, the test piece and the silver foil (dimensions: length 10 mm, width 5 mm, thickness 0.1) were used.
mm, purity: 99.9% or more) and 0.5 cc of pure water were added and kept for 20 hours while maintaining the temperature in the container at 85 ° C. Then, the S content WSO (mass%) in the silver foil after the test was measured by the combustion infrared absorption method.

4. Cold workability test: No. 1-7, No. 19-21, and No. 23
The sample was tested by measuring the critical compression strain during the compression test. The compression test piece has a cylindrical shape with a diameter of 15 mm and a height of 22.5 mm, and is compression-processed by a 600 t hydraulic press to obtain a limit compression strain (1 n (H0 / H): H0 is the initial test piece height, and H is a crack. There was a limit height, n
(X) represents the natural logarithm of X).

5. Corrosion resistance evaluation: The corrosion resistance evaluation test was performed by a salt spray test. As a test piece, a cylindrical one having a diameter of 10 mm and a height of 50 mm was used, and the surface was ground to # 400 with emery paper, washed, and then sprayed with a 5 mass% sodium chloride aqueous solution at 35 ° C. Exposure in the environment for 96 hours. The evaluation was performed visually, and "A" indicates that no rusting was observed, "B" indicates that spotted spots were found at several places, and red rust was confirmed within an area ratio of 5% or less. "C", area ratio 5%
The product in which red rust was confirmed in a range exceeding 1.0 was evaluated as "D". The above results are shown in Table 2.

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[Table 2]

From Table 2, the free-cutting alloy material constituted as the stainless steel according to the present invention has hot workability, cold workability and corrosion resistance comparable to those of the conventional stainless steels, and further, it can be machined. It can be seen that the performance is improved compared to conventional stainless steel. Further, as compared with the comparative alloy of No. 19, No. It can be seen that the alloys of the present invention Nos. 1 to 18 have improved machinability. Further, the comparative alloy No. Compared with No. 20, it can be seen that WSO is small and the outgas resistance is excellent. In addition, comparative alloy No. Compared with Nos. 27 to 29, the alloy No. of the present invention. It can be seen that Nos. 22 to 26 have improved machinability. That is, it can be seen that the invention alloy of the present invention has comparable corrosion resistance and hot workability to the comparative alloy, but has improved machinability and also improved outgas resistance.

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[Brief description of drawings]

FIG. 1 is a second invention alloy No. 1 of the experiment conducted in Example 1.
The figure which shows the EDX analysis result of 2.

FIG. 2 is a schematic diagram of invention steel No. 1 in Example 1. The figure which shows the optical microscope observation image of 2.

FIG. 3 is a diagram showing an example of a Schaeffler state diagram.

─────────────────────────────────────────────────── ─── Continuation of front page (73) Patent holder 899000035 Tohoku Techno Arch Co., Ltd. 468 Aoba, Aramaki, Aoba-ku, Sendai-shi, Miyagi (73) Patent holder 801000016 Japan Industrial Technology Promotion Association Toranomon, Minato-ku, Tokyo 1 −19−5 Toranomon 1-chome Mori Building 5th floor (72) Inventor Kiyohito Ishida 3-5-20 Uesugi, Aoba-ku, Sendai City, Miyagi Prefecture (72) Inventor Katsunari Oikawa 4-1-34 Nishifunako, Shibata-cho, Shibata-gun, Miyagi Prefecture (72) Inventor Tetsuya Shimizu 2-1410 Takashima, Tenpaku-ku, Nagoya-shi, Aichi (72) Inventor Michio Okabe 137 Asahi-Momodai, Chita-shi, Aichi (72) Inventor, Takashi Ebata 23 Nishigataoka, Murata-cho, Shibata-gun, Miyagi Prefecture Tohoku Special Steel Co., Ltd. (56) Reference JP-A-11-1743 (JP, A) JP-A-9-49053 (JP, A) JP-A-11-323487 (JP, A) JP-A-5-1177 92 (JP, A) JP 2000-192202 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C22C 38/00-38/60 C22C 19/05 C22C 27/06 C22C 30 / 00

Claims (9)

(57) [Claims] 1. Over 2 to 50% by mass of Ni and 12 to 50
Mass% Cr, and 5-86.95 mass% Fe.
In the alloy, the content of C is 0.01 to 0.4 mass%, the content of Ti is WTi (mass%), and the content of Zr is WZr.
As (mass%), WTi + 0.52WZr is 0.03 ~
It contains at least one of Ti and Zr so as to be 3.5% by mass, and contains 0.01 to 1% by mass of S and 0.01 to 0.8% by mass.
At least one of Se and the total content of Ti and Zr is less than the total content of S and Se.
It is 1.55 times or more, further contains at least one of Ti and Zr as a metal element component, and as a binding component with the metal component,
C as an essential component and 1 selected from S and Se
It contains at least a kind or two or (Ti, Zr) based compound is formed in the tissue, the (Ti, Zr) based compound, composition formula (Ti, Zr)
_At least a compound represented by ₄ (S, Se) ₂ C ₂
It is configured as an austenite-containing stainless steel containing
Free-cutting alloy material. 2. The austenite-containing stainless steel
Is mainly composed of Fe and mainly composed of an austenite phase.
The free-cutting alloy material according to claim 1, which is formed . 3. Si: 4 mass% or less, Mn: 4 mass% or less
Below, P: 0.05 mass% or less, O: 0.03 mass% or less
Below, N: 0.05% by mass or less, according to claim 1 or 2
Free-cutting alloy material described . 4. Cu of 4 mass% or less and 4 mass% or less
4. At least one of Co is contained.
The free-cutting alloy material according to any one of 1 . 5. 0.1 to 10% by mass of Mo, and 0.1 to
Claims containing at least either 10% by weight of W
The free-cutting alloy material according to any one of Items 1 to 4 . 6. Bi of 0.01 to 0.2% by mass, and
One or more selected from Pb of 01 to 0.3 mass%
The free-cutting alloy material according to any one of claims 1 to 5, containing the above . 7. Ca, Mg, B, REM (however, REM
Is a metal element classified as Group 3A in the Periodic Table of Elements.
1 or more selected from 1 or 2 or more) in total
It contains 0.0005 to 0.01 mass%.
The free-cutting alloy material according to any one of 6 above . 8. One selected from Nb, V, Ta and Hf
The above-mentioned content of 0.01 to 0.5% by mass is contained.
7. The free-cutting alloy material according to any one of 7 . 9. An alloy material test piece having a length of 15 mm and a width of
It has a rectangular parallelepiped shape of 25 mm and a thickness of 3 mm, and the entire surface
Grinded with # 400 emery paper
Prepared as a sulfur component getter, vertical 10 mm, horizontal
5mm, 0.1mm thick silver foil with a purity of 99.9% or more
And 0.5 cc of pure water together with the test piece
Enclose it in a 250cc container and keep the temperature in the container at 85 ° C.
After raising the temperature so as to be maintained for 20 hours,
When the sulfur content WSO is analyzed, the value of WSO is
The free-cutting alloy material according to any one of claims 1 to 8, which has a content of 0.035 mass% or less .