WO2017150738A1

WO2017150738A1 - Stainless steel member and method for manufacturing same, and stainless steel component and method for manufacturing same

Info

Publication number: WO2017150738A1
Application number: PCT/JP2017/008675
Authority: WO
Inventors: 西田　純一
Original assignee: 日立金属株式会社
Priority date: 2016-03-04
Filing date: 2017-03-06
Publication date: 2017-09-08
Also published as: US20190040506A1; JP2019167630A; JPWO2017150738A1; JP6784960B2; JP6631860B2

Abstract

Provided are a stainless steel component having excellent corrosion resistance and abrasion resistance and a method for manufacturing the same, a stainless steel member suitable for fabricating the component, and a method for manufacturing the stainless steel member. The present invention is a stainless steel member having a thickness of 0.3 mm or less and having a component composition comprising, in terms of mass%, 0.10-0.40% C, 1.00% or less of Si, 0.10-1.50% Mn, 10.0-18.0% Cr, and 2.00% or less of N, the remainder being Fe and impurities, wherein the amount of N in a depth range of at least 0.05 mm from the surface of the stainless steel member is 0.80-2.00 mass%. The present invention is also a method for manufacturing the stainless steel member, a stainless steel component which uses the stainless steel member, and a method for manufacturing the stainless steel component.

Description

Stainless steel member and manufacturing method thereof, and stainless steel component and manufacturing method thereof

The present invention relates to a stainless steel member that can be used for stainless steel parts such as sliding parts such as piston rings and cams of internal combustion engines, and tool parts such as molds and blades, and a method for manufacturing the same. And this invention relates to said stainless steel components and its manufacturing method.

Conventionally, it is known that various characteristics can be improved by adding nitrogen to stainless steel. By adding nitrogen, the characteristics of stainless steel can be enhanced without adding expensive alloy elements.
For example, in the case of stainless steel having an austenite structure, it is advantageous for improving the corrosion resistance. In general, the corrosion resistance of stainless steel can be evaluated by a Pitting Resistance Equivalent (PRE) defined by the component composition of the stainless steel, and the larger this value, the better the corrosion resistance. Then, when evaluated by “Cr + 3.3Mo + 30N—Mn”, which is proposed as an example of a definition formula of the pitting corrosion index, the effect of improving the corrosion resistance when 1% by mass of nitrogen is added is about 9% by mass of molybdenum. It is almost the same as that.
For example, in the case of stainless steel having a martensite structure, it is advantageous for improving the quenching hardness. That is, when quenching is performed on stainless steel, nitrogen in the steel dissolves in the structure in the same manner as carbon, which is the same interstitial element. And according to the amount of nitrogen dissolved in this structure, the hardness of the stainless steel is improved.

As a method for producing nitrogen-added stainless steel, for example, in the melting process, an ingot with a high nitrogen content is produced by adding nitride to the molten steel or dissolving it in a pressurized nitrogen atmosphere. There is a way to do it. However, if the amount of nitrogen added at the time of molten steel is large, nitrogen gas is generated during solidification and blowholes are generated in the ingot. In addition, when electroslag remelting is used for melting in the above nitrogen atmosphere, a special modification for maintaining a pressurized nitrogen atmosphere is required for a normal electroslag remelting apparatus.

Therefore, as another method for producing nitrogen-added stainless steel, there is a method of heating the “solidified” stainless steel in a pressurized nitrogen atmosphere, ammonia, nitrogen plasma, or a salt bath. By this method, nitrogen is dissolved or nitride is precipitated on the surface of the stainless steel being heated to form a “nitrogen-enriched layer” in which nitrogen is added to the surface of the stainless steel. . Thereby, even if it does not add nitrogen to the whole stainless steel, the corrosion resistance and wear resistance of stainless steel can be improved.

As a specific method for forming the above-mentioned “nitrogen-enriched layer”, “nitride precipitation method (so-called nitriding treatment)” in which stainless steel is treated in an environment around 500 ° C. using ammonia or nitrogen plasma is known. Widely used. By this nitride precipitation method, a nitrogen-enriched layer on which fine nitrides are deposited is formed on the surface of the stainless steel, and the surface of the stainless steel after the nitrogen-enriched layer is formed is hardened. However, in this case, a brittle nitrogen compound such as ε-nitride is easily generated in the nitrogen-enriched layer.
On the other hand, as another method for forming the “nitrogen-enriched layer”, there is “nitrogen absorption treatment” in which stainless steel is heated and held at a temperature of, for example, about 1000 ° C. in a nitrogen atmosphere. In the case of nitrogen absorption treatment, nitrogen is added to the surface of stainless steel exclusively in the form of a solid solution, so that a lot of brittle nitrogen compounds are not generated unlike the above-described nitride precipitation method. And since it processes at high temperature compared with the nitride precipitation method, it is advantageous to forming a nitrogen-rich layer thickly.

The following has been proposed as a method of adding nitrogen to the surface of stainless steel by nitrogen absorption treatment.
First, for a stainless steel having an austenitic structure, for example, “ferritic stainless steel containing Cr: 18 to 24% and Mo: 0 to 4% in mass%, an inert gas containing nitrogen gas and 800 ° C. or more” In this method, a nitrogen absorption treatment is carried out by contacting the product to austenite the entire product or a part thereof to austenite to produce a product that does not contain Ni (Patent Document 1).
Further, “by nitriding a stainless steel part close to the final shape in a nitrogen-containing gas atmosphere at a temperature of 1000 to 1200 ° C., followed by cooling at a rate such that precipitation of nitrides is avoided. A method of forming an austenite surface layer containing dissolved nitrogen of 30 wt% or more on stainless steel has been proposed (Patent Document 2).

On the other hand, the following is proposed about the stainless steel which has a martensitic structure. For example, “We have a chemical composition containing Cr: 13.0 to 20.0% by weight, C: 0.1% or less, N: 0.1% or less and the balance being Fe and inevitable impurities. In addition, a chromium-based stainless steel plate having a nitrided layer, a stainless steel plate having a structure in which the inner layer portion is a single phase of a ferrite phase and a martensite phase appears in the nitrided surface layer portion has been proposed. (Patent Document 3). The martensite phase structure has a thickness of about 10 to 30 μm and a hardness of about 250 HV.
“The component is wt%, C is in the range of 0.26 to 0.40%, Si is in the range of 1% or less, Mn is in the range of 1% or less, P is in the range of 0.04% or less, S In the range of 0.03% or less, Cr in the range of 12 to 14%, N in the range of 0.02% or less, B in the range of 0.0005 to 0.002%, the balance being Fe and inevitable A martensitic stainless steel is proposed in which a steel material composed of mechanical impurities is heated in a nitrogen atmosphere so that the nitrogen concentration in the surface layer is 0.25 to 0.3%, and is then water quenched. Patent Document 4). The heating in the nitrogen atmosphere is a solid-phase nitrogen absorption method in which the heating is performed in a high-temperature nitrogen atmosphere at 1200 ° C. and 0.1 MPa for 1 to 3 hours, whereby the nitrogen concentration in the steel surface layer is 0.25 to 0.3. The surface hardness of 700 HV or higher is obtained by absorbing nitrogen until it reaches%.
In addition, a stainless steel containing 0.4 mass% or less of carbon is heated to Ac1 point or more, 0.2 to 0.8 mass% of nitrogen is diffused on the surface, and directly quenched and tempered as it is. Has proposed a method of curing the surface (Patent Document 5).

JP 2006-316338 A Japanese Patent Laid-Open No. 7-188733 Japanese Patent Laid-Open No. 5-31336 JP 2010-138425 A German Patent Application Publication No. 4033706

The methods proposed in the above-mentioned patent documents are effective methods for obtaining stainless steel added with nitrogen. However, these conventional methods of stainless steel absorb less nitrogen and therefore lack corrosion resistance and wear resistance in more severe corrosive environments, improving corrosion resistance and wear resistance in the state of products (parts). There was room for improvement.
An object of the present invention is a stainless steel member having a nitrogen-enriched layer formed on the surface by nitrogen absorption treatment, and the surface of the stainless steel part after quenching and tempering can achieve excellent corrosion resistance and wear resistance. And a method of manufacturing the same. And it is providing the stainless steel components excellent in said corrosion resistance and abrasion resistance, and its manufacturing method.

That is, in the present invention, by mass, C: 0.10 to 0.40%, Si: 1.00% or less, Mn: 0.10 to 1.50%, Cr: 10.0 to 18.0% , N: 2.00% or less, the composition of the remaining Fe and impurities, a stainless steel member having a thickness of 0.3 mm or less,
A stainless steel member in which the N content in the range from the surface of the stainless steel member to a depth of at least 0.05 mm is 0.80 to 2.00% by mass.

Further, the present invention, in mass%, C: 0.10 to 0.40%, Si: 1.00% or less, Mn: 0.10 to 1.50%, Cr: 10.0 to 18.0% N: 2.00% or less, the composition of the remaining Fe and impurities, a martensitic structure having an average crystal grain size of 20 μm or less, and a stainless steel part having a thickness of 0.3 mm or less,
A stainless steel part in which the N content in the range from the surface of the stainless steel part to a depth of at least 0.05 mm is 0.80 to 2.00% by mass, and the hardness in this range is 650 HV or more.

Further, the present invention, in mass%, C: 0.10 to 0.40%, Si: 1.00% or less, Mn: 0.10 to 1.50%, Cr: 10.0 to 18.0% , N: Less than 2.00%, balance Fe and impurity component composition, stainless steel having a thickness of 0.3 mm or less, heated to 860 ° C. or higher in a nitrogen atmosphere, and then cooled It is a manufacturing method of a member.
And this invention is a manufacturing method of the stainless steel component which quenches and tempers the stainless steel member manufactured by the manufacturing method of an above-described stainless steel member.

At this time, in each of the above-described present inventions, the component composition of the stainless steel, the stainless steel member, or the stainless steel part is further in terms of mass%, Mo: 4.00% or less, W: 8.00% Hereinafter, at least one of Ni: 1.00% or less and Nb: 0.10% or less may be included.

According to the present invention, the corrosion resistance and wear resistance of the surface of the stainless steel part can be improved. Thereby, the characteristics of various sliding parts, molds, blades and the like used in a corrosive environment can be improved.

Sample No. evaluated in the examples. Fig. 6 is a drawing-substituting photograph showing the state of rust generation after a salt spray test of No. 6 (invention example). Sample No. evaluated in the examples. It is a drawing substitute photograph which shows the generation | occurrence | production state of the rust after the salt spray test of 1 (comparative example). Sample No. evaluated in the examples. It is a micro photograph which shows an example of the cross-sectional structure | tissue of thickness direction of 1 (comparative example). Sample No. evaluated in the examples. It is a micro photograph which shows an example of the cross-sectional structure | tissue of thickness direction of 3 (invention example). Sample No. evaluated in the examples. It is a micro photograph which shows an example of the cross-sectional structure | tissue of thickness direction of 4 (comparative example). Sample No. evaluated in the examples. 5 is a microphotograph showing an example of a cross-sectional structure in the thickness direction of No. 5 (Example of the present invention). Sample No. evaluated in the examples. 5 is a calibration curve diagram showing the relationship between the N content and the hardness when the N content of this component composition is changed for stainless steel having the component composition of the base material of 5 (Example of the present invention). Sample No. evaluated in the examples. 21 and 22 (examples of the present invention) and sample nos. It is a figure which shows an example of the hardness distribution of the thickness direction of 23 and 24 (comparative example). Sample No. evaluated in the examples. 21 and 22 (examples of the present invention) and sample nos. It is a figure which shows an example of N amount distribution of the thickness direction of 23 and 24 (comparative example).

A feature of the present invention is that a "stainless steel member" having a nitrogen-enriched layer formed on the surface by nitrogen absorption treatment is formed on a "stainless steel part" produced by quenching and tempering. In other words, the corrosion resistance and wear resistance of the surface (that is, the working surface of various stainless steel parts) are improved.
That is, with respect to wear resistance, first, stainless steel itself as a base material is adjusted to a component composition that “expresses a martensite structure” by quenching and tempering. Then, a nitrogen-enriched layer to which a large amount of nitrogen of “0.80 to 2.00% by mass” is added to the above component composition is formed on the surface of the base material. The surface of the stainless steel part after quenching and tempering (that is, the nitrogen-enriched layer) has achieved a high hardness of “650 HV or higher”.
In addition to the formation of the nitrogen-enriched layer described above, in addition to the formation of the nitrogen-enriched layer described above, the component composition of the stainless steel that expresses the martensite structure further adjusts the carbon content to a lower level. The formation of coarse carbides in the martensitic structure is suppressed, and the occurrence of corrosion starting from these carbides is suppressed. On this, the average grain size confirmed in the martensite structure is set to “20 μm or less”, so that the grain boundaries that are the starting points of fracture and corrosion are dispersed, and fatigue characteristics and corrosion resistance are improved. .
Hereinafter, the stainless steel member of the present invention will be described together with a stainless steel part using the member and a preferable manufacturing method for achieving these.

(1) The stainless steel member of the present invention is, in mass%, C: 0.10 to 0.40%, Si: 1.00% or less, Mn: 0.10 to 1.50%, Cr: 10.0 ˜18.0%, N: 2.00% or less, balance Fe and impurity component composition.
As described above, the stainless steel member of the present invention has a component composition in which a quenching and tempering structure “expresses a martensite structure” in a stainless steel part produced by quenching and tempering the member. And about this component composition, it is as follows.

C: 0.10 to 0.40 mass% (hereinafter simply expressed as “%”)
C is an element that suppresses stabilization of ferrite and increases the hardness of the martensite structure. And in said martensitic structure, it is an element which suppresses the coarsening of a crystal grain.
However, when there is too much C, coarse Cr-based carbides crystallize in the solidified structure during solidification in the melting process. And this coarse Cr type carbide | carbonized_material does not lose | disappear in the martensitic structure after quenching and tempering, but this becomes a starting point of corrosion and degrades the corrosion resistance of the surface of stainless steel parts. Moreover, cold workability falls and the yield until it finishes to the stainless steel member and stainless steel component of a predetermined shape falls. At this time, in the present invention, the hardness of the surface of the stainless steel part is largely achieved by the formation of a nitrogen-enriched layer, which will be described later, so that the composition of the stainless steel itself is designed to be “low carbon”. Is possible.
Therefore, the C content is 0.10 to 0.40%. In addition, about a minimum, Preferably it is 0.11%, More preferably, it is 0.12%, More preferably, it is 0.13%. Further, the upper limit is preferably 0.38%, more preferably 0.36%, and still more preferably 0.34%.

-Si: 1.00% or less Si is an element that is used as a deoxidizing agent or the like during steelmaking and can be inevitably included. And when there is too much Si, hardenability will fall. Therefore, the Si content is set to 1.00% or less. Preferably it is 0.80% or less, More preferably, it is 0.65% or less, More preferably, it is 0.50% or less. The lower limit is not particularly limited. And the content of 0.01% or more is realistic.

・ Mn: 0.10 to 1.50%
Mn is an element that is used as a deoxidizing agent or the like during steelmaking and can be inevitably included. And in this invention, it is an element which has the effect which accelerates | stimulates the solid solution of nitrogen to a structure | tissue.
However, if it is too much, austenite becomes stable and it becomes difficult to obtain a martensite structure.
Therefore, the Mn content is set to 0.10 to 1.50%. In addition, about a minimum, Preferably it is 0.20%, More preferably, it is 0.30%, More preferably, it is 0.40%. The upper limit is preferably 1.30%, more preferably 1.10%, and still more preferably 1.00%.

・ Cr: 10.0-18.0%
Cr is an element that forms an amorphous passive film on the surface of the stainless steel and imparts corrosion resistance to the stainless steel. It also has an effect of increasing the amount of nitrogen that can be dissolved in stainless steel, and is an element that works effectively in the formation of a nitrogen-enriched layer described later.
On the other hand, if there is too much Cr, the ferrite is stabilized, martensite formation does not proceed sufficiently at the center of the stainless steel part of the present invention, and the strength of the whole part decreases. Further, at the time of forming a nitrogen-enriched layer, which will be described later, it takes time for the surface structure of the stainless steel being heated in the nitrogen absorption treatment to dissolve nitrogen into austenite, and the production efficiency is lowered.
Therefore, the Cr content is set to 10.0 to 18.0%. Preferably, it is less than 15.0%. More preferably, it is 14.0% or less. Moreover, Preferably it is 12.0% or more.

-N (nitrogen): 2.00% or less In the present invention, it is assumed that nitrogen that can be contained in "stainless steel" before nitrogen absorption treatment is performed is an "impurity". For example, the nitrogen amount is 0.02% or less. However, if the shape of the stainless steel is small (thin), such as a plate, strip, or foil, the purpose that nitrogen wants to absorb when nitrogen absorption treatment is performed In some cases, it can be absorbed beyond the surface of the stainless steel, which is a part of the stainless steel, to the central part of the stainless steel (that is, over the entire stainless steel).
Therefore, the content of nitrogen in the state of the stainless steel member is 2.00%, assuming the level of impurities before the nitrogen absorption treatment is performed, and eventually the amount that can be added by the nitrogen absorption treatment. The following.

In the stainless steel member of the present invention, the component composition including the above-described element species and the balance being Fe and impurities can be a basic component composition. And it is also possible to contain the following element seed | species with respect to this basic component composition.

Mo: 4.00% or less as required Mo is an effective element for enhancing the corrosion resistance of stainless steel. And it has the effect which strengthens the function of the passive film by Cr in a solid solution state. The passive film made of Cr itself has a self-healing function. And Mo has the function of increasing the repair amount of the passive film by increasing the amount of Cr at the spot where the passive film is deposited when Cr is deposited. Furthermore, Mo has a great effect of promoting nitrogen absorption of stainless steel.
On the other hand, if there is too much Mo, ferrite will be stabilized like Cr, and the strength of the entire stainless steel part will be reduced. Further, when forming a nitrogen-enriched layer, which will be described later, it takes time for the nitrogen absorption treatment, and the production efficiency is lowered.
Therefore, Mo can contain 4.00% or less as needed. Preferably it is 3.00% or less, More preferably, it is 2.50% or less, More preferably, it is 2.00% or less. In addition, when it contains Mo, Preferably it is 0.10% or more, More preferably, it is 0.50% or more, More preferably, it is 1.00% or more.

W: 8.00% or less, if necessary W has the same effect as Mo. And since the atomic weight of W is about twice that of Mo, the W content for obtaining an effect amount equivalent to that of Mo can be regarded as twice the amount of Mo.
Therefore, W can contain 8.00% or less as needed. Preferably it is 6.00% or less, More preferably, it is 5.00% or less, More preferably, it is 4.00% or less. And when cost etc. are considered, 2.00% or less is especially preferable. In the case where W is contained, it is preferably 0.10% or more, more preferably 0.30% or more, and further preferably 0.50% or more in consideration of cost and the like.

Ni: 1.00% or less as required Ni has an effect of suppressing further progress of corrosion at the initial stage of corrosion. It also has the effect of increasing the toughness of the base in the organization.
On the other hand, when there is too much Ni, austenite becomes stable and it becomes difficult to obtain a martensite structure.
Therefore, Ni can contain 1.00% or less as needed. In the present invention in which the stainless steel part has a martensite structure, it is important to suppress the Ni content to 1.00% or less. Preferably it is 0.90% or less, More preferably, it is 0.80% or less. In addition, when it contains Ni, Preferably it is 0.10% or more, More preferably, it is 0.20% or more, More preferably, it is 0.40% or more.

Nb: 0.10% or less as required Nb has an effect of suppressing the coarsening of the martensite crystal grains in the stainless steel part after quenching and tempering.
However, when there is too much Nb, nitrogen produces | generates Nb nitride, solute nitrogen will reduce, and the improvement effect of hardness will fall.
Therefore, Nb can contain 0.10% or less as needed. Preferably it is 0.09% or less, More preferably, it is 0.08% or less. In addition, when it contains Nb, Preferably it is 0.01% or more, More preferably, it is 0.03% or more.

The component composition described above can be applied not only to the “stainless steel member” of the present invention but also to the “stainless steel part” of the present invention obtained by quenching and tempering the stainless steel member. And it is applicable also to "stainless steel" which is a base material of these stainless steel members and stainless steel parts, before the nitrogen absorption process mentioned later is performed (before a nitrogen enriched layer is formed in the surface). When the component composition of the stainless steel member (or steel part) and the stainless steel as the base material is compared, the amount of N increased in the stainless steel member by the nitrogen absorption treatment described later is small relative to the total component composition. is there. Therefore, the component composition of the stainless steel member (or steel part) and the stainless steel that is the base material thereof is less than 2.00% (that is, N contained in the stainless steel member or stainless steel part). It can be considered substantially the same in its entirety, except that it is less than the upper limit of the quantity.

(2) The stainless steel member of the present invention has a nitrogen-enriched layer on the surface of the stainless steel described in (1) above, and the nitrogen content of the nitrogen-enriched layer is nitrogen in the central portion of the stainless steel. It is equal to or greater than the amount and is 0.80 to 2.00% by mass.
The stainless steel member of the present invention is obtained by adding nitrogen to the surface of this member in order to achieve excellent corrosion resistance and wear resistance in the state of a stainless steel part produced by quenching and tempering. It has an “enriched layer”. The nitrogen-enriched layer is formed by adding “directly” nitrogen to the above-described stainless steel component composition by a nitrogen absorption treatment described later.
That is, the component composition of the nitrogen-enriched layer according to the present invention is the addition of a predetermined amount of nitrogen to the component composition of the stainless steel (base material) before the nitrogen-enriched layer is formed. The component composition of the stainless steel after the analysis is “re-analyzed”. The nitrogen-enriched layer according to the present invention has a reanalyzed component composition in which the amount of nitrogen contained in the stainless steel base material (that is, the central portion of the stainless steel after the nitrogen-enriched layer is formed) And an effective N (nitrogen) amount of “0.80 to 2.00% by mass”.

By adding nitrogen to the surface of stainless steel as a base material and providing a nitrogen-enriched layer, the surface of the stainless steel part (that is, the nitrogen-enriched layer) can be increased in hardness. Regarding the effect of increasing the hardness, carbon has the same effect as nitrogen. However, with respect to the amount of each element added to the stainless steel, in the case of carbon, the effect of improving the hardness is saturated when the amount of addition reaches 0.80% by mass. On the other hand, in the case of nitrogen, the hardness is improved even after the addition amount reaches 0.80 mass%. However, if the amount of nitrogen added exceeds about 2.00% by mass, the toughness decreases. Therefore, the nitrogen amount of the nitrogen-enriched layer according to the present invention is set to 0.80 to 2.00% by mass in the definition of the above component composition. Preferably it is 0.85 mass% or more, More preferably, it is 0.90 mass% or more. More preferably, it is 1.00 mass% or more. The surface of the stainless steel part can achieve a high hardness of 650 HV or higher by the nitrogen content. Preferably it is 670HV or more, More preferably, it is 700HV or more. More preferably, it is 720HV or more. Although it is not necessary to specify the upper limit of the hardness, 800 HV or less is realistic.

At this time, the nitrogen added to the surface of the stainless steel is adjusted to the above-mentioned “component that expresses the martensite structure” by adjusting the component composition of the stainless steel. Is prompted. Regarding the effect of this solid solution, carbon has the same effect as nitrogen. However, at the time of heating in the nitrogen absorption treatment described later, nitrogen has a higher solid solution ability in the austenite structure than carbon. And since nitrogen has strong affinity with Cr contained in a large amount of the stainless steel according to the present invention, the solid solution amount of nitrogen in the nitrogen-enriched layer can be increased. On the other hand, the formation amount of brittle ε-nitride in the nitrogen-enriched layer is reduced, and the formation amount of coarse carbide due to the low carbonization of the stainless steel is also reduced. Due to these comprehensive effects, the surface of the stainless steel part of the present invention achieves the improvement in corrosion resistance that was effective in the austenitic stainless steel in addition to the above-described increase in hardness.

Then, such a nitrogen-enriched layer having an effective N-component composition is formed on the surface of the stainless steel member (or stainless steel part) with an effective thickness of at least about 0.05 mm. This is effective in improving the corrosion resistance and wear resistance of stainless steel parts. The thickness is preferably 0.1 mm or more, more preferably 0.15 mm or more. The stainless steel member has an “effective nitrogen-enriched layer” having the above effective N amount and effective thickness on the surface, thereby improving the corrosion resistance and wear resistance of the stainless steel part. it can.

And when the shape of the stainless steel member of the present invention is, for example, a plate material, a strip material, or a foil material, and the thickness is 0.3 mm or less, the surface of the stainless steel member is at least 0.05 mm deep. Nitrogen-enriched layer with a sufficient thickness (depth) relative to the thickness of the stainless steel member is ensured by setting the range of N to 0.80 to 2.00% by mass of nitrogen. It is possible to improve the corrosion resistance and wear resistance of the stainless steel part. And in the stainless steel member of this invention whose thickness is 0.3 mm or less, it is preferable to have said nitrogen enriched layer in the both surfaces (front and back). The component composition of the nitrogen-enriched layer is as follows: “In mass%, C: 0.10 to 0.40%, Si: 1.00% or less, Mn: 0.10 to 1.50%, Cr: 10.0 to 18.0%, N: 0.80 to 2.00%, balance Fe and impurity component composition ”.
The lower limit of the thickness of the stainless steel member of the present invention is not particularly required. However, in terms of manufacturing efficiency and handling properties, for example, 0.02 mm or more is realistic.

In addition, in the stainless steel member of the present invention having a thickness T of 0.3 mm or less, the center of the thickness of the stainless steel member (that is, the position at a depth of T / 2 from the surface of the stainless steel member) or the center The amount of N in the part (that is, the range excluding the range from the surface of the stainless steel member to a depth of at least 0.05 mm) is the amount of N in the nitrogen-enriched layer (that is, the amount of N of 0.80% by mass or more). It does not have to be included. At this time, the amount of N at the center and the center of the stainless steel member is maintained, for example, when the stainless steel base material is used. Specifically, the amount of nitrogen is within a range of less than 2.00%. It is conceivable that the N amount is lower than the N amount of the enriched layer, or the N amount is less than 0.80%. And it is thought that the hardness of the center of a stainless steel part obtained by performing quenching and tempering on such a stainless steel member and the hardness of the central part is less than 650 HV. For example, the hardness when a stainless steel base material is quenched and tempered “as is”.

On the other hand, the N amount of the center or central portion of the stainless steel member of the present invention may, of course, be equivalent to (the same value as) the N amount (0.80 to 2.00% by mass) of the nitrogen-enriched layer. If the shape of the stainless steel base material is thin (small), nitrogen may be absorbed up to the center of the stainless steel base material when nitrogen absorption treatment is performed. In other words, this is the case when the “entire” of the stainless steel member is a nitrogen-enriched layer.
When the thickness T of the stainless steel member of the present invention is 0.1 mm or less, when the surface has the above effective nitrogen-enriched layer (thickness ≧ 0.05 mm), the stainless steel member The amount of N at the center of (that is, the position at a depth of T / 2 from the surface of the stainless steel member) is also (necessarily) equivalent to (same as) that of the nitrogen-enriched layer. And when the stainless steel member of the present invention has the above effective nitrogen-enriched layer on both surfaces (front and back surfaces) of the stainless steel member, the component composition of this stainless steel member (or parts) is In the whole, “in mass%, C: 0.10 to 0.40%, Si: 1.00% or less, Mn: 0.10 to 1.50%, Cr: 10.0 to 18.0% , N: 0.80 to 2.00%, remaining Fe and impurity component composition ”. Even such a stainless steel member can achieve excellent corrosion resistance and wear resistance when finished into a stainless steel part.

(3) In the stainless steel member of the present invention, the nitrogen-enriched layer having the above-mentioned component composition is formed by heating and holding the stainless steel as the base material at 860 ° C. or higher in a nitrogen atmosphere. Is preferred. And it is preferable to cool the stainless steel (member) after forming this nitrogen rich layer.
The effect of the amount of nitrogen that contributes to the improvement of the hardness of martensitic stainless steel is slightly lower than that of carbon. Therefore, when the low-carbon stainless steel according to the present invention is used as a base material, a large amount of nitrogen can be added to the nitrogen-enriched layer in increasing the hardness to form the nitrogen-enriched layer on the surface. A technique is needed.
Therefore, “nitrogen absorption treatment” in which stainless steel is heated and held in a nitrogen atmosphere is effective as a method for adding nitrogen to the surface of stainless steel. As the nitrogen atmosphere, for example, nitrogen gas can be used. As a specific example, the atmosphere contains 90% by volume or more of this nitrogen gas. However, conventionally, when nitrogen of “0.80 mass% or more” is added to the surface of stainless steel by this nitrogen absorption treatment, the stainless steel is heated to a high temperature exceeding 1000 ° C. and held for a long time. There was a need. And if this high temperature and long time heating and holding, a large amount of nitrogen can be added, but at the same time, there is a problem that the crystal grains of the entire stainless steel become coarse. When the crystal grains become coarse, strength characteristics deteriorate and fatigue strength deteriorates.

In contrast, in the case of the stainless steel proposed by the present invention, the component composition is adjusted so as to increase the amount of nitrogen dissolved in the austenite structure, so that the nitrogen enrichment can be achieved at a holding temperature of 860 ° C. or higher. It is possible to add 0.80% by weight or more of nitrogen to the layer. In the case of conventional stainless steel, the amount of nitrogen added to the nitrogen-enriched layer at the same holding temperature is limited to around 0.5% by mass. Further, when the holding time is a short time of about several minutes assuming a continuous heating furnace or the like, the limit is around 0.3% by mass. Furthermore, since the thickness of the proposed stainless steel of the present invention is 0.3 mm or less, it is assumed that N absorbed from the surface of the stainless steel by the above nitrogen absorption treatment diffuses to the center of the stainless steel. However, a sufficient amount of N can be secured even on the surface of the stainless steel, and a nitrogen-enriched layer having an effective thickness (depth) can be formed.

In the case of the present invention, after forming the above nitrogen-enriched layer on the surface of stainless steel, it is important to “cool once” the stainless steel on which the nitrogen-enriched layer is formed to form a stainless steel member. It is. For example, cooling to 200 ° C. (including room temperature) at most. And if this cooled stainless steel member is again heated to the quenching temperature and quenched, crystal grains can be refined by repeatedly passing through the transformation point. By quenching and heating, new austenite grains are formed in the structure of stainless steel, so the grains are subdivided and the average grain size in the martensitic structure of the stainless steel part (that is, the old austenite grain size) is increased. It can be “20 μm or less”. By setting the average crystal grain size to 20 μm or less, the fatigue resistance and corrosion resistance of the stainless steel part can be improved. Preferably it is 18 micrometers or less, More preferably, it is 16 micrometers or less, More preferably, it is 14 micrometers or less.
It is not necessary to specify the lower limit of the average crystal grain size. However, 8 μm or more is realistic.

In the nitrogen absorption treatment according to the present invention, the upper limit of the holding temperature is preferably 1000 ° C. or less in consideration of the coarsening of crystal grains. And it is preferable to set the optimal combination of holding temperature and holding time within this temperature range. For example, the holding time is 1 hour or more or 2 hours or more. Alternatively, the holding temperature is 6 hours or less or 5 hours or less. In addition, by making the nitrogen atmosphere during the nitrogen absorption treatment “pressurized atmosphere” (including atmospheric pressure), absorption of nitrogen to the stainless steel surface is promoted, which is particularly effective for shortening the holding time. is there.
In the nitrogen absorption treatment according to the present invention, a preferable holding temperature is 870 ° C. or higher. More preferably, it is 880 degreeC or more, More preferably, it is 890 degreeC or more. Especially preferably, it is 900 degreeC or more. Further, a more preferable holding temperature is 980 ° C. or lower, more preferably 970 ° C. or lower.

In the case of the present invention, the stainless steel (member) after the nitrogen absorption treatment is once cooled as described above, and the structure of the formed nitrogen-enriched layer is a ferrite structure or a martensite structure. And When the cooled stainless steel member is quenched, the structure of the nitrogen-enriched layer is austenite transformed again in the heating step, new austenite grains are generated, and the refinement of crystal grains is achieved. The quenching temperature is, for example, 950 to 1200 ° C.
And it is preferable that the heating atmosphere to said quenching temperature shall be "non-oxidizing atmosphere" which can suppress the chemical influence (change of N amount) to a nitrogen rich layer. As the non-oxidizing atmosphere, for example, a vacuum environment (including a reduced pressure atmosphere) or a non-oxidizing gas such as hydrogen gas can be used. And as a specific example, it is a non-oxidizing atmosphere of purity containing 90 volume% or more of non-oxidizing gas. Moreover, after quenching, it is preferable to perform a sub-zero treatment in order to promote transformation into a martensite structure and stabilize the refined crystal grains.
Then, by tempering the quenched stainless steel member, a stainless steel part having an average crystal grain size of 20 μm or less in the structure and a hardness of the surface nitrogen-enriched layer of 650 HV or more is obtained. Can do. The tempering temperature is, for example, 150 to 650 ° C. When emphasizing corrosion resistance, tempering is preferably “low temperature tempering”. For example, 200 to 400 ° C. By lowering the tempering temperature, it is possible to suppress the precipitation of Cr-based carbides and nitrides in the nitrogen-enriched layer, and the deficiency of Cr in the portion adjacent to this precipitation location can be suppressed. Corrosion resistance can be maintained high.

In the case of the present invention, the stainless steel before performing the nitrogen absorption treatment may be subjected to a soaking treatment that is held for a long time at a high temperature of around 1200 ° C. at the time of ingot, for example. In the case of the stainless steel according to the present invention, a component design is performed so that coarse Cr carbides do not crystallize during solidification. However, in a large ingot, coarse Cr carbide may crystallize due to segregation. In this case, the coarse Cr-based carbide can be dissolved in the structure by the soaking process described above.
Moreover, it is preferable that the stainless steel before performing the nitrogen absorption treatment is arranged in a substantially part (product) shape by machining or the like. If it is the state of the low carbon steel which does not contain nitrogen, it will be easy to process and a manufacturing yield will also be large. Therefore, it is desirable to process the shape as close to the final shape as possible before curing by adding nitrogen.

A 10 kg molten metal melted in a high-frequency induction melting furnace was cast to produce a stainless steel ingot having chemical components shown in Table 1. Note that the N content of these ingots was 0.02% or less. Next, hot forging with a forging ratio of about 10 was performed on these ingots, and after cooling, annealing was performed at 780 ° C. to obtain annealed materials. And 1 mm-thick board | plate material was cut out from these annealing materials, the cold rolling was performed to this board | plate material, and the strip | belt material whose thickness T is 0.15 mm was obtained.

After performing the “nitrogen absorption treatment” in which the stainless steel base material made of the above-mentioned strip is heated in a nitrogen atmosphere made of atmospheric nitrogen gas (purity 99%), the furnace is cooled to 600 ° C. or lower, and the furnace The outside was taken out (room temperature), and the stainless steel member was produced. Table 1 shows the heating temperature and holding time in the nitrogen absorption treatment. Table 1 also shows the nitrogen content of the nitrogen-enriched layer formed by the nitrogen absorption treatment.
In this example, since the shape of the stainless steel subjected to the nitrogen absorption treatment was a thin strip with a thickness of 0.15 mm, the entire surface in the thickness direction was more than both surfaces (front and back surfaces). Over the course of time, it was confirmed by EPMA (electron beam microanalyzer) that nitrogen of the same concentration was added. Therefore, the amount of nitrogen contained in the nitrogen-enriched layer could be replaced with the amount of nitrogen obtained for the entire sample including the surface to the center of the sample. In the analysis of the amount of nitrogen as the entire sample, the amount of nitrogen generated by melting the entire sample was obtained from the thermal conductivity, and this was used as the amount of nitrogen contained in the nitrogen-enriched layer.

Next, this stainless steel member was quenched and tempered to produce a stainless steel part. In the quenching, the above stainless steel member was put in a furnace having an atmosphere of hydrogen gas (atmospheric pressure, purity 99%) heated to 1100 ° C. for 2 minutes, and then rapidly cooled. After quenching, sub-zero treatment at −75 ° C. was performed. The tempering temperature was 350 ° C.
Then, the average crystal grain size of the martensite structure of the stainless steel part and the hardness of the nitrogen-enriched layer were measured.
The average crystal grain size was measured by a line segment method. First, the structure of the cross section (so-called TD cross section) in the thickness direction of the stainless steel part was observed with an optical microscope (× 1000) (FIG. 3). Next, a straight line (150 μm) in length corresponding to the thickness was drawn on the observed visual field, and the number of grain boundaries intersecting the straight line was counted. Then, the above-mentioned length of 150 μm was divided by the number of counts to obtain a temporary average crystal grain size. Then, this operation is performed on a total of 10 different straight lines, 5 in the thickness direction of the stainless steel part and 5 in the direction perpendicular to the stainless steel part (length direction). The particle size was obtained and averaged to obtain the average crystal particle size.
The measurement position of the hardness was set to the center in the thickness direction of the strip, which can be regarded as the position of the “nitrogen-enriched layer” for the above reason.
These measurement results are shown in Table 1.

In addition, a salt spray test in which 5% salt water at 35 ° C. was sprayed for 5 hours on the surface of the stainless steel part was evaluated to evaluate the corrosion resistance. Corrosion resistance was evaluated by observing the occurrence of rust on the surface. The evaluation criteria are based on the rust occurrence status shown in FIG. 1 and FIG. 2 as “◎ (large effect)” where rust occurrence is lighter than in FIG. 2 was marked as “◯ (effective)”, and the case where rust was more noticeable than that in FIG. 2 was marked “Δ (ineffective)”. These results are also shown in Table 1.

Sample No. 1 aims at increasing the hardness of the surface of stainless steel parts by “the effect of carbon addition” by increasing the carbon content of stainless steel used as a base material and not performing nitrogen absorption treatment. . The average crystal grain size in the martensite structure was 20 μm or less. And the result of the salt spray test is the generation | occurrence | production state of the rust shown in FIG. 2, and the rust generate | occur | produced as a whole. For reference, FIG. 3 shows the sample No. when the tempering temperature is 550 ° C. 1 is a microphotograph of a cross-sectional structure in the thickness direction observed with an optical microscope (× 1000 magnification) (upper and lower limits in the figure correspond to both surfaces of a strip). It is easy to confirm the shape of the carbide by observing at a tempering temperature of 550 ° C. From FIG. In 1, a slightly coarse carbide was confirmed.

Sample No. Nos. 2 to 4 are obtained by subjecting stainless steel having the same composition to a base material to nitrogen absorption treatment under various conditions.
Sample No. No. 2 exhibited excellent corrosion resistance due to the appropriate component composition of stainless steel as a base material. The average crystal grain size of the martensitic structure was 20 μm or less. However, the amount of nitrogen contained in the nitrogen-enriched layer was low and the hardness was less than 650 HV due to the low heating and holding temperature during the nitrogen absorption treatment.
Sample No. No. 3 also showed sufficient corrosion resistance due to the appropriate component composition of stainless steel as a base material, although there was some nitride formation in the nitrogen-enriched layer. The average crystal grain size of the martensite structure was also 20 μm or less. And, due to the fact that the heating and holding temperature at the time of nitrogen absorption treatment was appropriate as 950 ° C., the amount of nitrogen contained in the nitrogen-enriched layer is as high as 0.97 mass%, and the hardness reaches 700 HV, High hardness was achieved. 4 is a sample No. when the above tempering temperature is 550 ° C. for reference. 3 shows a micrograph of the cross-sectional structure of No. 3. The point of observation is the same as in FIG. 3 (hereinafter, the same applies to FIGS. 5 and 6). Sample No. Compared to 1 (FIG. 3), coarse carbides were not observed, and a uniform martensite structure was obtained.
Sample No. No. 4 increases the heating / holding temperature during nitrogen absorption treatment to 1100 ° C. However, the holding time was 5 minutes, and after this holding, “direct quenching” was performed as it was without passing through “cooling” before quenching heating which is the next step (that is, according to the present invention). The stainless steel “component” was not passed through.) As a result, the amount of nitrogen contained in the nitrogen-enriched layer is as small as 0.23% by mass, and the average crystal grain size is also 20 μm due to the small number of passes through the transformation point in these series of heat treatment processes. It was over. No improvement was seen in both the hardness and corrosion resistance characteristics. For reference, FIG. 5 shows sample No. 1 when the tempering temperature is 550 ° C. 4 shows a microstructure photograph.

Sample No. 5 is a case where stainless steel as a base material contains about 2% of Mo. By containing Mo, the base material easily absorbs nitrogen, and the amount of nitrogen contained in the nitrogen-enriched layer is increased. And sample no. 5 is coupled with the fact that the structure of the entire sample was almost completely martensitic (FIG. 6 is a microphotograph of the cross-sectional structure of sample No. 5 when the tempering temperature is 550 ° C.). The hardness of the nitrogen-enriched layer achieved a high hardness exceeding 700 HV. Sample No. No. 5 was also excellent in corrosion resistance. And the average crystal grain size was 20 μm or less.

Sample No. 6 is obtained by adding a small amount of Nb to stainless steel as a base material. The amount of nitrogen contained in the nitrogen-enriched layer was high, and the average crystal grain size of the martensite structure was 20 μm or less, which was excellent in both hardness and corrosion resistance characteristics.

Sample No. Nos. 7 and 8 are obtained by subjecting stainless steel having the same component composition adjusted to a higher carbon content to a base material and nitrogen absorption treatment under various conditions. In both samples, there was no formation of coarse carbides in the structure, and excellent corrosion resistance was achieved. However, sample No. No. 7 had a low nitrogen content and a hardness of less than 650 HV due to the low heating and holding temperature during the nitrogen absorption treatment. In both samples, the average crystal grain size of the martensite structure was 20 μm or less.

Sample No. 9 is prepared by adjusting the Cr contained in the stainless steel as the base material to about 8%. And by reducing this amount of Cr, it became difficult for the base material to absorb nitrogen, and the amount of nitrogen contained in the nitrogen-enriched layer was low. And sufficient corrosion resistance was not obtained. The average crystal grain size of the structure exceeded 20 μm.

Sample No. 10 and 11 are obtained by adding W to stainless steel as a base material. As in the case of adding Mo, the amount of nitrogen contained in the nitrogen-enriched layer increased to achieve high hardness exceeding 700 HV and sufficient corrosion resistance. In both samples, the average crystal grain size of the martensite structure was 20 μm or less.

Sample No. No. 12 is obtained by increasing Cr contained in stainless steel as a base material to 17% and adding about 2% Mo. This makes it easier for the base material to absorb nitrogen, and a large amount of nitrogen can be added to the nitrogen-enriched layer even with nitrogen absorption treatment under almost the same conditions as other samples. And the structure | tissue was fully martensitic and the high hardness which the nitrogen enrichment layer reached about 750HV was achieved. Sample No. No. 12 was also excellent in corrosion resistance. The average crystal grain size of the structure was 20 μm or less.

Sample No. No. 13 is obtained by adding Ni to stainless steel as a base material. And the nitrogen content which a nitrogen enrichment layer contains was high, and the average crystal grain diameter of the martensite structure | tissue is also 20 micrometers or less, and achieved the outstanding hardness and sufficient corrosion resistance.

Sample No. in Table 1 Using the ingot having the component composition of the base material of 5, four types of thickness T strips (or plate materials) shown in Table 2 were produced in the same manner as in Example 1. The stainless steel base material made of these strips is subjected to a “nitrogen absorption treatment” in which it is heated in a nitrogen atmosphere made of atmospheric nitrogen gas (purity 99%), and then cooled to 600 ° C. or lower. Then, it was taken out of the furnace (room temperature) to produce a stainless steel member. The heating temperature and holding time in this nitrogen absorption treatment were 950 ° C. × 3 hours. And the depth from the surface of the nitrogen rich layer (N> = 0.80 mass%) formed in the surface of the stainless steel member by this nitrogen absorption process was measured. At this time, the amount of N for specifying the nitrogen-enriched layer is substantially the same even when measured in the state of a stainless steel part after quenching and tempering, which will be described later, and thus was measured at the time of the stainless steel part.

Next, the above stainless steel member was quenched and tempered to produce a stainless steel part. Quenching is performed by putting the above stainless steel member in a furnace made of hydrogen gas (atmospheric pressure, purity 99%) heated to 1100 ° C. for 2 minutes in common for all thicknesses. It was supposed to be cooled rapidly. After quenching, sub-zero treatment at −75 ° C. was performed. The tempering temperature was 350 ° C.
And the average crystal grain diameter of the martensitic structure of these stainless steel parts and the N amount, depth, and hardness of the nitrogen-enriched layer formed on the stainless steel parts were measured.

The procedure for measuring the average crystal grain size was in accordance with Example 1. For the measurement of the N amount, depth, and hardness of the nitrogen-enriched layer, first, sample No. For a stainless steel having a component composition of 5 base material, a “calibration curve” showing the relationship between the N content and the hardness when the N content of this component composition changed was prepared (FIG. 7). Then, in the structure of the cross section in the thickness direction of the stainless steel part (so-called TD cross section), the hardness distribution in the thickness direction is measured, and the N amount corresponding to the hardness obtained by this measurement is calculated by the above calibration. By comparing with the lines, it was possible to know the distribution of the converted N amount corresponding to the hardness distribution of the four types of stainless steel parts shown in Table 2. FIG. 8 shows the hardness distribution in the thickness direction of the above four types of stainless steel parts.
Then, the amount of N from the surface of the above four types of stainless steel parts is evaluated, and the portion whose value is “0.80 to 2.00% by mass” is defined as a nitrogen-enriched layer. Was able to identify the depth of. As a result of the measurement using the calibration curve, the above four types of stainless steel parts had a converted N amount of “2.00% by mass or less” in the entire range in the thickness direction. FIG. 9 shows the N amount distribution in the thickness direction of the above four types of stainless steel parts.

Then, a salt spray test in which 5% salt water at 35 ° C. was sprayed on the surface of the stainless steel part for 5 hours to evaluate the corrosion resistance. Corrosion resistance was evaluated according to Example 1, with “◎ (high effect)”, “◯ (effective)”, and “△ (no effect)”. The above results are summarized in Table 2.

In Table 2, Sample No. 21 and 22 are stainless steel parts (members) having a thickness of 0.3 mm or less, and N absorbed from both surfaces (front and back surfaces) by the nitrogen absorption treatment reached the center. The N amount is “0.80 to 2.00% by mass” over the entire thickness range (that is, the entire stainless steel part (member) can be regarded as a nitride-enriched layer). After quenching and tempering, a surface hardness of 650 HV or higher was achieved. And the average crystal grain size was also 20 micrometers or less, and it was excellent also in corrosion resistance.
On the other hand, sample No. 23 and 24 are stainless steel parts (members) having a thickness exceeding 0.3 mm. Sample No. 23 and 24, the N content at the center is higher than the nitrogen content (0.02% or less) of the stainless steel base material, and the N absorbed from the surface by the nitrogen absorption treatment reaches the center. It was. However, the thickness (depth from the surface) of the nitrogen-enriched layer where the N amount is “0.80 mass% or more” is as small as less than 0.05 mm, and the depth of 0.05 mm from the surface after quenching and tempering. The hardness at this position was less than 650 HV. Note that the average crystal grain size exceeded 20 μm. Corrosion resistance was measured according to Sample No. Compared to 21 and 22.

Claims

In mass%, C: 0.10 to 0.40%, Si: 1.00% or less, Mn: 0.10 to 1.50%, Cr: 10.0 to 18.0%, N: 2.00 %, A component composition of the balance Fe and impurities, a stainless steel member having a thickness of 0.3 mm or less,
A stainless steel member characterized in that the N amount in the range from the surface of the stainless steel member to a depth of at least 0.05 mm is 0.80 to 2.00% by mass.
2. The stainless steel member according to claim 1, wherein the component composition of the stainless steel member further includes Mo: 4.00% or less in terms of mass%.
3. The stainless steel member according to claim 1, wherein the component composition of the stainless steel member further includes W: 8.00% or less in terms of mass%.
The stainless steel member according to any one of claims 1 to 3, wherein the composition of the stainless steel member further includes Ni: 1.00% or less in terms of mass%.
5. The stainless steel member according to claim 1, wherein the component composition of the stainless steel member further includes Nb: 0.10% or less in terms of mass%.
In mass%, C: 0.10 to 0.40%, Si: 1.00% or less, Mn: 0.10 to 1.50%, Cr: 10.0 to 18.0%, N: 2.00 A stainless steel part having a martensite structure with an average crystal grain size of 20 μm or less and a thickness of 0.3 mm or less, comprising a component composition of% or less, the balance Fe and impurities,
Stainless steel characterized in that the N amount in the range from the surface of the stainless steel part to a depth of at least 0.05 mm is 0.80 to 2.00% by mass, and the hardness in the range is 650 HV or more. parts.
The stainless steel part according to claim 6, wherein the composition of the stainless steel part further includes Mo: 4.00% or less in terms of mass%.
8. The stainless steel part according to claim 6, wherein the component composition of the stainless steel part further includes W: 8.00% or less by mass%.
The stainless steel part according to any one of claims 6 to 8, wherein the component composition of the stainless steel part further includes Ni: 1.00% or less in terms of mass%.
The stainless steel part according to any one of claims 6 to 9, wherein the component composition of the stainless steel part further includes Nb: 0.10% or less in terms of mass%.
In mass%, C: 0.10 to 0.40%, Si: 1.00% or less, Mn: 0.10 to 1.50%, Cr: 10.0 to 18.0%, N: 2.00 Stainless steel member comprising a stainless steel having a composition of less than%, the balance Fe and impurities, and having a thickness of 0.3 mm or less, heated to 860 ° C. or more in a nitrogen atmosphere and then cooled. Manufacturing method.
The method for producing a stainless steel member according to claim 11, wherein the component composition of the stainless steel further includes Mo: 4.00% or less in terms of mass%.
The method for producing a stainless steel member according to claim 11 or 12, wherein the component composition of the stainless steel further includes W: 8.00% or less in terms of mass%.
The method for producing a stainless steel member according to any one of claims 11 to 13, wherein the composition of the stainless steel further includes Ni: 1.00% or less in terms of mass%.
The method for producing a stainless steel member according to claim 11, wherein the component composition of the stainless steel further includes Nb: 0.10% or less by mass%.
A method for producing a stainless steel part, comprising quenching and tempering the stainless steel member produced by the method for producing a stainless steel member according to any one of claims 11 to 15.