JPWO2008013305A1 - Stainless steel sheet for parts and manufacturing method thereof - Google Patents

Abstract

Provided are a stainless steel plate capable of improving workability (formability, etching property) and fatigue characteristics while having good strength and ductility, and a method for producing the stainless steel plate. Furthermore, the stainless steel sheet is inexpensively and industrially stably supplied. When the whole stainless steel is 100 mass%, C is 0.01 to 0.08 mass%, Si is 0.1 to 2.0 mass%, Mn is 3.0 mass% or less, and Cr is 10. 0 to 20.0% by mass, Ni is 3.0 to 12.0% by mass, N is 0.02 to 0.24% by mass, and “Md = 500-458 (C + N) −” 9 (Si + Mn) -14Cr-20Ni ”and the compound having a maximum diameter of 20 μm or more among the compounds formed by the respective components is 30 per 5 g of stainless steel. It is assumed that the metal structure of the entire stainless steel is a mixed structure of recrystallized grains and non-recrystallized parts.

Description

  TECHNICAL FIELD The present invention relates to a stainless steel plate processed as an industrial product and a method for producing the same, and more specifically, stainless steel for parts having high strength, high fatigue characteristics, excellent workability, and high flatness and low residual stress. It is related with a steel plate and its manufacturing method. That is, the present invention relates to a stainless steel plate that exhibits excellent performance in many products and parts manufactured from a stainless steel plate or steel strip (hereinafter sometimes collectively referred to as “stainless steel plate”), and its manufacture. Regarding the method. In particular, the present invention relates to a stainless steel plate suitable for a wide variety of parts that are incorporated and used in industrial products, which are highly accurate and complicated as products become smaller and lighter, and a method for manufacturing the same.

  A wide variety of parts are used inside and outside various industrial products such as automobiles, home appliances, IT equipment, and mobile phones. Although there are a wide variety of materials for each part, many metal materials are applied, and stainless steel is often used among them. Many of these parts made of stainless steel are manufactured from stainless steel sheets by methods such as press working and etching.

  For example, in the case of press working, the stainless steel plate is cut into a predetermined size by cutting, blanking or the like, and then formed into a predetermined shape using a mold. A typical example is a spring component. Spring components are used in many industrial products and may be used in many parts of a product. In addition, there are many types of spring parts, and they are roughly classified into disc springs and leaf springs according to their shapes. Specific examples include a washer inserted between a bolt and a nut, a small disc spring used under a cellular phone button, a gasket used in an automobile or a motorcycle, a metal packing, and the like.

  On the other hand, the etching process forms a pattern on the surface of the plate by a photoresist method, and a part of the material is corroded and removed (etched) by chemical means such as immersion in acid or spraying to obtain a shape corresponding to the pattern. That's it. Etching is often applied to the processing of precision parts where pressing is difficult. These include, for example, small parts such as gimbals (springs) used for fixing magnetic heads, printer paper feed gears, shadow masks for conventional TVs that have a very large number of small holes, and meshes for printed circuit board printing. it can.

In parts using such stainless steel, the tendency of the parts to become smaller, lighter, more complicated and more accurate in recent years has progressed, and the following various characteristics have been further required.
・ Strength: Stress is applied to spring parts, and there are many other parts with side surfaces of the structure, and high strength is required for the material to reduce the size and weight (decrease in rigidity).
-Formability: With the increasing complexity and precision of parts, it is necessary to process more complicated shapes with high precision, so excellent formability is required. In general, the formability is proportional to the elongation (ductility) of the material, and the strength and the elongation are in an opposing (incompatible) relationship, and both high strength and excellent formability are required.
Etching property: Similarly, as parts become more complex and more accurate, excellent etching property is required to obtain a smooth processed surface free from defects such as locally generated holes (etching pits).
・ Fatigue characteristics: Spring parts are often subjected to repeated fluctuating stress, and since the amount of deformation increases with downsizing and weight reduction, excellent fatigue characteristics are required. Moreover, although it is excellent in a raw material stage, it is often deteriorated greatly by molding, and it is required to be excellent as a part and to have high reliability.
・ Flatness: Highly accurate ・ Compatible parts shape is acquired stably, and the defect rate is reduced (increases the yield) when incorporated into products that are smaller and lighter. Must be stable.
Residual stress: When taken from a relatively large material (relative to the part), the part is released from the surrounding constraints and changes shape due to the release of residual stress. That is, the part does not exhibit a predetermined shape, and the defect rate when incorporated into a product (which is reduced in size and weight) increases (yield decreases). For this reason, the residual stress is required to be low and stable.

  Conventionally, metastable austenite (γ) stainless steel such as SUS301 and SUS304 has been used for the above-described components. In the austenitic stainless steel, transformation from a γ parent phase to a hard martensite phase (processing-induced martensite (α ′) transformation) can be caused by processing at room temperature. Thereby, it is possible to obtain a stainless steel plate having high strength while having a certain degree of ductility. This processing is usually performed by cold rolling, and the strength can be adjusted by adjusting the rolling reduction of the cold rolling. High strength can be obtained while having ductility because only the part is hardened by the process-induced martensite (α ') transformation, and local deformation is suppressed, and deformation into a soft untransformed part (γ part). Is propagated, and the whole is uniformly deformed to show high elongation. This is called the TRIP effect. Because of these characteristics, metastable austenite (γ) stainless steel is also classified as a stainless steel strip for springs in the JIS standard (JIS G 4313).

  Further, regarding the fatigue characteristics of these stainless steels, Patent Document 1 discloses the one based on the limitation of the size of the compound that becomes the starting point of fracture. Patent Document 2 discloses an improvement in etching properties by limiting the distribution of compounds that serve as starting points of etching pits (holes). Furthermore, Patent Document 3 discloses improvement of formability and fatigue characteristics by crystal grain refinement.

  The production process of these metastable austenite (γ) stainless steels will be described generally with the steps shown in FIG. That is, the molten ingot is hot-rolled and annealed as necessary, and then cold-rolled and annealed repeatedly to reduce the thickness to a predetermined thickness as shown in FIG. Subsequently, temper rolling, shape correction, and strain relief annealing for strain relief are performed. Among these, in temper rolling, the thickness can be reduced to the product sheet thickness, and at the same time, the performance can be adjusted by work hardening. When the temper rolling is completed, the thickness is reduced to a predetermined thickness so that the target performance can be obtained with the product thickness. Thereafter, within a range in which the performance is not greatly changed, the residual stress is reduced by the flatness improvement by shape correction and the strain relief annealing for strain relief.

  Further, Patent Document 4 and Patent Document 5 disclose a TA (Tension-Annealing) process as an improvement of these series of manufacturing steps. In this method, heating is performed at a relatively low temperature while applying tension within a range in which the performance after temper rolling is not greatly changed, and flatness improvement and residual stress reduction can be performed simultaneously.

  Furthermore, as another manufacturing method, Patent Document 6 and Patent Document 7 describe a stainless steel manufacturing method having a temper annealing method and a high-performance metastable γ-based stainless steel plate obtained by the temper annealing method. Is disclosed. The outline of the process is shown in FIG. This is to adjust the performance of a stainless steel material having a predetermined composition by softening a material that has been work-hardened by cold rolling to a product plate thickness by temper annealing. Thereby, the material becomes a mixed structure of the recrystallized grains and the non-recrystallized portion that remains affected by the pre-processing, and high strength and high ductility can be achieved by optimizing the ratio. Furthermore, during temper annealing, transformation from work-induced martensite (α ') phase to austenite (γ) parent phase (this is referred to as "reverse transformation"), recovery and recrystallization occur, which causes residual stress Reduced. In addition, since the reverse transformation is accompanied by a volume change, it is possible to adjust the softening by applying a tension, and to adjust the performance and correct the shape in a relatively short time. That is, it is possible to reasonably and stably manufacture a high-performance material suitable for a component material used by being incorporated in a product.

  Patent Documents 8 to 10 specify a rolling condition and a heat treatment condition for a stainless steel plate as a material, and introduce a transition or martensite into the crystal grain to increase the etching rate in the crystal grain. A stainless steel sheet is disclosed. This is because the smoothness of the etched surface is improved by making the etching rate in the crystal grains equal to that of the crystal grain boundaries.

JP 2005-290449 A JP 2000-273586 A JP-A-5-279802 JP-A-10-34237 JP 2001-226718 A Japanese Patent No. 3603726 JP 2002-194506 A JP-A-2005-314772 Japanese Patent Laying-Open No. 2005-320586 Japanese Patent Application Laid-Open No. 2005-320587

  However, there has been a need for a stainless steel plate that can cope with the recent trend toward smaller, lighter, more precise and higher precision parts, and further improvement of the above-described characteristics has been a problem. Each invention shown in Patent Documents 1 to 3 has a limit and further performance improvement has been demanded. In particular, in the spring material, improvement in fatigue characteristics after being processed as a product and improvement in workability (formability and etching property) capable of accurately processing a miniaturized component have been problems.

  The manufacturing method has the same problem, and it has been a problem to adopt a method of manufacturing a stainless steel plate that can solve the above-described problem. However, the conventional manufacturing method and the manufacturing methods of Patent Literature 4 and Patent Literature 5 have a limit in achieving both high strength and high ductility of the material. In addition, since the material is thinner and stronger, it is difficult to correct the shape and the plate shape tends to deteriorate. In addition, the strain relief annealing has been a factor that hinders productivity due to a long time. Furthermore, since various parts are used widely, the plate thickness and hardness are different, and the amount of use may be relatively small, these problems become remarkable, resulting in a significant increase in product cost.

  The manufacturing methods described in Patent Document 6 and Patent Document 7 have problems to cope with further improvement in workability by promoting the trend of reducing the size and weight of products and parts, expanding the variety of products, and the like.

  In the stainless steel plate for photoetching described in Patent Documents 8 to 10, although smoothness of etching can be obtained, it cannot always be said to have good strength, ductility, and fatigue characteristics. Thus, there is a problem that further performance improvement is necessary.

  Then, this invention makes it a subject to provide the manufacturing method of this stainless steel plate and stainless steel plate which can improve workability (formability, etching property) and fatigue characteristics while providing favorable intensity | strength and ductility. Furthermore, another object of the present invention is to stably supply the stainless steel plate of the present invention at low cost and industrially by the method for producing the stainless steel plate.

  As a result of intensive studies, the present inventors have obtained the following knowledge and the like in order to solve the above-described problems, and completed the present invention. That is, a mixed structure for improving the properties of a stainless steel sheet that has not been obtained by a conventional stainless steel sheet and its manufacturing method (a high-ductility recrystallized structure and an unrecrystallized structure in which a high-strength work-induced martensite phase remains) To obtain a tissue that is a mixture). And the influence of the final rolling rate and material composition in a series of rolling processes for that was investigated in detail. As a result, it has been found that workability, fatigue characteristics, and the like can be improved by a stainless steel plate having a mixed structure as described later and its manufacturing method.

The details are based on the following knowledge.
(A) The performance is improved by the structure having a mixed structure. This is because the recrystallized part in the mixed structure has the effect of strengthening by grain refinement and the suppression of non-uniform deformation at the grain boundary due to the increase in density, while the non-recrystallized part in the mixed structure is reversely transformed to work hardening. There is a TRIP effect due to processing-induced α ′ transformation from the γ phase. This allows the material to maintain high strength from their combined effects. In addition, deformation progresses uniformly and formability (ductility) is improved. Further, the etching property can be considered in the same manner, and it is considered that the etched surface becomes uniform due to the refinement of crystal grains and the increase in the single structure of the γ parent phase. As a result, the non-uniform portion that becomes the starting point of fatigue failure disappears, and the fatigue characteristics after molding and after etching are improved.

  (B) While optimizing various conditions such as the material composition, and adjusting the mixed structure of the stainless steel plate and the distribution of the underlying compounds, the workability and fatigue characteristics of the material can be improved. Specifically, by adding 30 or less compounds having a maximum diameter of 20 μm or more per 5 g of mass in addition to the mixed tissue, defects that are manifested by processing are not observed, and the processed part surface becomes smooth. As a result, a fatigue strength of 90% or more with respect to that before processing is maintained after processing. Since fatigue failure occurs due to stress concentration on the defect, it is considered that the same strength improvement can be achieved by reducing this defect.

  (C) For the production method, the tension applied to the stainless steel plate during production changes the proportion of recrystallized grains consisting of the γ phase in the structure of the stainless steel plate, or the proportion of γ phase in the unrecrystallized part. Change it. This is because the reverse transformation from the α ′ (work-induced martensite) phase with volume change to the γ parent phase is controlled by the tension during temper annealing when a production method having temper annealing is applied. . Since the softening is moderated by the application of the tension, it is considered that the increase in the tension suppresses the reverse transformation and increases the amount of α ′ (processing induced martensite) remaining. That is, the metal structure of stainless steel can be controlled by the tension.

  However, on the other hand, it was found that when the tension was excessive, the γ phase in the non-recrystallized portion was transformed into the α ′ phase during cooling. This is presumably because, in addition to the processing strain in which the γ phase in the non-recrystallized portion remains, a martensitic transformation (α ′) induced by processing occurs at a predetermined temperature or lower during cooling due to the influence of tension. Therefore, the tension to be applied must be performed within a predetermined range in consideration of reverse transformation.

  (D) As for the production method, the final cold rolling can pulverize and refine the compound by increasing the reduction ratio. This is one of the advantages of making the performance adjustment a separate process (temper annealing), and in temper rolling, it is inevitable that implementation at a predetermined processing rate is necessary for performance adjustment.

  The present invention will be described below.

In the invention described in claim 1, C is 0.01 to 0.08 mass%, Si is 0.1 to 2.0 mass%, Mn when the whole stainless steel is 100 mass%. 3.0% by mass or less, Cr 10.0 to 20.0% by mass, Ni 3.0 to 12.0% by mass, N 0.02 to 0.24% by mass, And the formula Md = 500-458 (C + N) -9 (Si + Mn) -14Cr-20Ni in which the value of mass% of the contained component is substituted
The compound having a chemical composition in which the Md value represented by the formula 0 to 80 is satisfied, and the balance is an inevitable impurity, and the maximum diameter is 20 μm or more among the compounds formed by the respective components, the inherent amount of the compound is stainless steel. By providing a stainless steel plate for parts, the number of which is 30 or less per 5 g of steel mass, and the metal structure of the entire stainless steel is a mixed structure of recrystallized grains and non-recrystallized parts. Resolve.

In the invention described in claim 2, C is 0.01 to 0.08 mass%, Si is 0.1 to 2.0 mass%, Mn when the whole stainless steel is 100 mass%. 3.0 mass% or less, Cr 10.0-20.0 mass%, Ni 3.0-12.0 mass%, N 0.02-0.24 mass%, and Nb, Ti, V Formula Md = 500-458 (C + N) -9 (in which each component is contained in an amount of 0.5% by mass or less selected from 1 and the mass% value of each component contained therein is substituted. Si + Mn) -14Cr-20Ni-65Nb-27Ti-61V
The compound having a chemical composition in which the Md value represented by the formula 0 to 80 is satisfied, and the balance is an inevitable impurity, and the maximum diameter is 20 μm or more among the compounds formed by the respective components, the inherent amount of the compound is stainless steel. By providing a stainless steel sheet for parts, the number of which is 30 or less per 5 g of steel mass, and the metal structure of the entire stainless steel is a mixed structure of recrystallized grains and non-recrystallized parts. Resolve.

  The invention described in claim 3 is characterized in that the average grain size of the recrystallized grains of the stainless steel sheet for parts described in claim 1 or 2 is 10 μm or less.

  The invention described in claim 4 is characterized in that the mixed structure of the stainless steel sheet for parts described in claim 3 is an austenite phase of 70% by mass or more.

In the invention according to claim 5, when the entire stainless steel is 100 mass%, C is 0.01 to 0.08 mass%, Si is 0.1 to 2.0 mass%, Mn 3.0% by mass or less, Cr 10.0 to 20.0% by mass, Ni 3.0 to 12.0% by mass, N 0.02 to 0.24% by mass, And the formula Md = 500-458 (C + N) -9 (Si + Mn) -14Cr-20Ni in which the value of mass% of the contained component is substituted
A first cold rolling step (S1) in which a material having a chemical composition in which the Md value represented by the formula 0 to 80 is satisfied and the balance is an inevitable impurity is cold-rolled at least once, and the first cold rolling The first annealing step (S2) arranged after the first cold rolling step in combination with the step, and the final rolling provided on the subsequent step side of the first annealing step, the rolling reduction is 20% or more, And the 2nd cold rolling process (S3) from which the total reduction with 1st cold rolling will be 60% or more, and hold | maintain the said raw material after a 2nd cold rolling process at 650-1000 degreeC for 300 second or less And the said subject is solved by the manufacturing method of the stainless steel plate for components which has the 2nd annealing process (S4) which gives tension | tensile_strength and gives a tension | tensile_strength below 0.2% yield strength of the raw material in this hold | maintained temperature.

In the invention according to claim 6, when the entire stainless steel is 100 mass%, C is 0.01 to 0.08 mass%, Si is 0.1 to 2.0 mass%, Mn 3.0 mass% or less, Cr 10.0-20.0 mass%, Ni 3.0-12.0 mass%, N 0.02-0.24 mass%, and Nb, Ti, V Formula Md = 500-458 (C + N) -9 (in which each component is contained in an amount of 0.5% by mass or less selected from 1 and the mass% value of each component contained therein is substituted. Si + Mn) -14Cr-20Ni-65Nb-27Ti-61V
A first cold rolling step (S1) in which a material having a chemical composition in which the Md value represented by the formula 0 to 80 is satisfied and the balance is an inevitable impurity is cold-rolled at least once, and the first cold rolling The first annealing step (S2) arranged after the first cold rolling step in combination with the step, and the final rolling provided on the subsequent step side of the first annealing step, the rolling reduction is 20% or more, And the 2nd cold rolling process (S3) from which the total reduction with 1st cold rolling will be 60% or more, and the raw material after a 2nd cold rolling process are hold | maintained at 650-1000 degreeC for 300 seconds or less. And the said subject is solved by providing the stainless steel plate for components components which has the 2nd annealing process (S4) which gives tension | tensile_strength by giving tension below 0.2% yield strength of the raw material in this hold | maintained temperature. .

  The invention according to claim 7 is the material at a temperature at which the tension in the second annealing step of the method for manufacturing a stainless steel sheet for parts according to claim 5 or 6 is maintained. It is characterized by being 40% or less of the% yield strength.

  The invention described in claim 8 further includes temper rolling after the second annealing step (S4) in the method for manufacturing a stainless steel plate for parts according to any one of claims 5 to 7. It is characterized by giving.

  ADVANTAGE OF THE INVENTION According to this invention, the stainless steel plate and its manufacturing method which can manufacture a wide variety of components accurately and with high reliability can be provided. In particular, in the present invention, it is possible to provide a stainless steel plate that is excellent in formability and fatigue characteristics after forming and has high reliability at low cost and industrially stably. In addition, in response to recent environmental problems, it is possible to further promote the effective use of resources by reducing the size and weight.

It is a figure for demonstrating 1 aspect of the flow of the manufacturing method of this invention. It is a graph which shows one example of the relationship between the temperature of a raw material, and 0.2% yield strength. It is a graph which shows the relationship between the hardness of a stainless steel plate created based on the result obtained by the present Example, and elongation. No. of this example. 4 and no. It is the photograph which expanded and showed the surface of the bending part in the case of 28. It is a figure for demonstrating one example of the manufacturing method of the conventional stainless steel plate. It is a figure for demonstrating the other example of the manufacturing method of the conventional stainless steel plate.

Explanation of symbols

S1 1st cold rolling process S2 1st annealing process S3 2nd cold rolling process S4 2nd annealing process

  The above-described operation and gain of the present invention will be made clear from the best mode for carrying out the invention described below.

The best mode of the present invention and preferred ranges thereof will be described below.
(1) Stainless steel plate First, the stainless steel plate of the present invention will be described. As described above, the stainless steel plate of the present invention is characterized by its composition and structure, Md value, and the aspect of the underlying compound. Each will be described below.

(1-1) Component The component contained in the present invention and the content thereof will be described. The main component of the stainless steel plate of the present invention is Fe, and the content shown below indicates a ratio when the entire stainless steel plate is 100 mass%.

-C: Content of C shall be 0.01-0.08 mass%. C is one of inexpensive and effective interstitial solid solution strengthening elements. The effect of strengthening the solid solution contained at 0.01% by mass or more is exhibited. On the other hand, the upper limit is 0.08% by mass. This is because C is a strong γ-stabilizing element, and excessive addition suppresses the processing-induced martensite (α ′) transformation that is necessary. Further, in the case of a production method including temper annealing, coarse carbide precipitates at grain boundaries typified by Cr ₂₃ C ₆ compounds during temper annealing, thereby degrading workability and corrosion resistance. A more preferable range of the C content is 0.02 to 0.07% by mass.

  Si: The Si content is 0.1 to 2.0% by mass. Si is an effective solid solution strengthening element. The reason why the lower limit value is set to 0.1% by mass or more is that this increases the high-temperature strength and facilitates acquisition of the above-described mixed structure, which is a feature of the present invention. The upper limit is set to 2.0% by mass because Si is also a ferrite (α) stabilizing element, and excessive addition increases the α ′ phase remaining during temper annealing. A more preferable range of the Si content is 0.2 to 1.8% by mass.

  -Mn: Mn content shall be 3.0 mass% or less. Mn is a γ-stabilizing element and is added in consideration of balance with other elements. The reason why the content is 3.0% by mass or less is that when it is added excessively, the α ′ phase cannot be obtained. Moreover, it is because an inclusion etc. may be formed and workability and corrosion resistance may be deteriorated. A more preferable range of the Mn content is 2.6% by mass or less.

  -Cr: Content of Cr is 10.0-20.0 mass%. Cr is one of the basic alloy elements of stainless steel. The reason why the content is set to 10.0% by mass or more is to obtain necessary corrosion resistance. The upper limit is set to 20.0% by mass because Cr is an α-stabilizing element and excessive addition increases the α ′ phase remaining after temper annealing. A more preferable range of the Cr content is 13.0 to 19.0 mass%.

  -Ni: Ni content is 3.0-12.0 mass%. Ni is also one of the basic alloy elements of stainless steel and is the most effective gamma stabilizing element. The lower limit is set to 3.0% by mass because it is indispensable to obtain a stable γ phase at room temperature. The reason why the upper limit value is set to 12.0% by mass is that it is necessary to cause the α ′ transformation within a predetermined range. A more preferable range of the Ni content is 3.5 to 11.5% by mass.

  -N: Content of N is 0.02-0.25 mass%. N is one of the effective interstitial solid solution strengthening elements like C, and can be dissolved in a solid solution at a higher temperature than C without forming a compound. That is, it is the main reinforcing element of the present invention. From this viewpoint, the lower limit value was set to 0.02% by mass. The reason why the upper limit is set to 0.25% by mass is that when it is added excessively, the hot workability is deteriorated and the production of the plate may be hindered. N, like C, is one of the powerful γ-stabilizing elements, and it also depends on suppressing the α ′ transformation. A more preferable range of the N content is 0.04 to 0.20%, a further preferable range is 0.08 to 0.02%, and a most preferable range is 0.10 to 0.20% by mass.

  -Nb: Content of Nb is 0.50 mass% or less. Nb precipitates a relatively stable and finely dispersed Nb compound even at a high temperature, facilitates acquisition of a mixed structure, and makes it possible to refine recrystallized grains by suppressing grain growth. The upper limit is set to 0.50% by mass because excessive addition forms a coarse compound and lowers the ductility of the material. Moreover, since it is an expensive substance, an upper limit is set from the viewpoint of cost. A more preferable range of Nb is 0.45% by mass or less.

  -Ti: Content of Ti is 0.50 mass% or less. Ti is considered to have the same effect as Nb. That is, the precipitation of the Ti compound facilitates the acquisition of the mixed structure, and the recrystallized grains can be refined. Furthermore, it is thought that a compound is formed more easily than Nb. The upper limit is set to 0.50% by mass because excessive addition forms a coarse compound and lowers the ductility of the material. The Ti content is more preferably 0.45% by mass or less.

  -V: V content is 0.50 mass% or less. V has the same effect as Nb and Ti. That is, the precipitation of the V compound facilitates the acquisition of the mixed structure and refines the recrystallized grains. The upper limit is set to 0.50% by mass because excessive addition forms a coarse compound and lowers the ductility of the material. A more preferable range of the V content is 0.001% by mass or more and 0.45% by mass or less.

  In addition to the above components, elements added from an industrial viewpoint, for example, Ca, Al or REM (rare earth metal) used as a deoxidizer during melting, and B, which is expected to improve hot workability, are added as necessary. You may contain so that it may become 0.3 mass% or less by quantity. Furthermore, when using scrap as a raw material, you may contain each of Cu and Mo which become inevitable at 0.4 mass% or less. Cu and Mo act as elements for adjusting the γ stability in the present invention. Further, inevitable impurities in a normal composition may be included.

(1-2) Md value Md value is calculated by the formula represented by Formula (1) or Formula (2) in the present invention, and the value is 0 to 80 ° C. Here, when at least one selected from Nb, Ti, and V, which is not an inevitable impurity, is added, formula (2) is used. When neither is added, it is calculated using equation (1). Moreover, the content (mass%) of a corresponding component is substituted for the symbols C, N, Si, Mn, Cr, Ni, Nb, Ti, and V in the formula, respectively.
Md = 500-458 (C + N) -9 (Si + Mn) -14Cr-20Ni (1)
Md = 500-458 (C + N) -9 (Si + Mn) -14Cr-20Ni
-65Nb-27Ti-61V (2)
The Md value is expressed in units of ° C. and indicates the ease of processing-induced martensite (α ′) transformation. The formula is formulated based on a series of experimental results in the present invention (30 ° C.) at which 50% of the whole transforms into α ′ phase when 30% tensile deformation is applied to a γ single phase material. It is. As described above, the present invention is intended for metastable γ-based stainless steel and utilizes the α ′ transformation, and therefore it is necessary to control the α ′ transformation. Therefore, the optimum Md value for this purpose was set to 0 to 80 ° C. More preferably, it is 10-70 degreeC.

(1-3) Aspect of Compound In the stainless steel plate of the present invention, in the compound contained in the stainless steel plate, those having a maximum diameter of 20 μm or more are inherent in 30 pieces or less per 5 g of the mass of the stainless steel plate. is there. Thereby, generation | occurrence | production of the defect resulting from a compound can be reduced. That is, it is considered that the material has excellent moldability and the probability that a coarse compound exists in the vicinity of the surface is extremely small. In the case of press working, unevenness and minute cracks due to a large difference in deformability between the two (raw material and coarse compound) are improved. Further, in the case of etching processing, the occurrence of local defects such as compound exposure due to the difference in corrosion resistance, and further, holes (etch pits) due to dropping off are eradicated. As a result, the surface of the machined part becomes smooth and the fatigue characteristics are improved. Further, this local defect is considered to be detected by measuring the maximum roughness of the surface of the processed part.

(1-4) Aspect of Structure The material structure of the stainless steel plate of the present invention is a “mixed structure” defined by a mixed structure of recrystallized grains and an unrecrystallized portion that remains affected by pre-processing. As a result, both high strength and high ductility can be achieved, and high flatness and low residual stress can be achieved. The mixed structure may have a structure composed of 70% by area or more of γ phase. By forming the γ phase as the main structure, the formability and fatigue characteristics are further improved. More preferably, it is 80 area% or more.

  By using the stainless steel plate as described above, it is possible to provide a stainless steel plate capable of improving workability (formability, etching property) and fatigue properties while being excellent in various properties. In addition, the grain size of recrystallization may be 10 μm or less. Thereby, the formability and fatigue characteristics resulting from crystal grain refinement are further improved. More preferably, it is 6 μm or less.

(2) Manufacturing method of stainless steel plate Next, one embodiment of the manufacturing method of the stainless steel plate of this invention is described. As shown in FIG. 1, the method for producing a stainless steel plate of the present invention includes a first cold rolling step (S1) that is at least one cold rolling step, and the first cold rolling step (S1). And at least one first annealing step (S2), a second cold rolling step (S3), and a second annealing step (S4) that is annealing for tempering. . Each will be described below.

(2-1) First cold rolling step (S1)
In the first cold rolling step (S1), a material that is hot-processed by adding the above-described components is supplied. In this step, the purpose is mainly to bring the dimensions of the material closer to the steel plate finally obtained. Therefore, it is not necessarily required to be performed once, and rolling may be performed several times. Specifically, the total rolling reduction with the second cold rolling performed later may be 60% or more, preferably 70% or more, more preferably 80% or more, and most preferably 90% or more. is there.

(2-2) First annealing step (S2)
This is a process that is paired with the first cold rolling process (S1), and is a process mainly intended to impart softening and ductility of the material. Therefore, the conditions are not particularly limited as long as the annealing process is normally performed. The said conditions are determined by the raw material supplied and the aspect of the steel plate finally obtained.

(2-3) Second cold rolling step (S3)
The second cold rolling step (S3) is a step that is arranged after the first cold rolling step (S1) and the first annealing step (S2) and performs the final cold rolling. In the second cold rolling step (S3), the thickness is reduced to the thickness of the stainless steel plate finally obtained. At this time, the thickness reduction is 20% or more in terms of rolling reduction, and the total rolling reduction with the first cold rolling is 60% or more. This is because a sufficient work-induced martensite (α ′) phase can be obtained by setting the rolling reduction to 20% or more. Furthermore, this makes it possible to refine crystal grains. Preferably it is 30% or more. In addition, the total reduction ratio of the first cold rolling and the second cold rolling was set to 60% or more because the compound was finely pulverized by increasing the reduction ratio, and a coarse compound of 20 μm or more was obtained. The number can be reduced. This makes it possible to reduce the maximum diameter of the compound and reduce the number of coarse compounds of 20 μm or more. At this time, it is preferable to cold-roll using a small-diameter work roll because the effect of crushing coarse compounds is high.

(2-4) Second annealing step (S4)
The second annealing step (S4) is the last annealing step, and the material aspect of the stainless steel plate that can be finally obtained is thereby determined. Specifically, in this step, the annealing temperature was set to 650 to 1000 ° C., and the holding time was set to 300 seconds or less. This is defined from the viewpoints of adjusting the mechanical properties of the material and affecting the metal structure of the material, such as crystal grain growth, and the production efficiency. This makes it possible to obtain a stainless steel plate that is efficient and has high flatness and low residual stress.

  Furthermore, in the second annealing step (S4), the annealing temperature is set and tension is applied to the material. The magnitude of the tension is not more than 0.2% proof stress of the material at the annealing temperature. More preferably, it is 40% or less of the 0.2% proof stress. The reverse transformation is adjusted by applying tension to the material with such a size. Accordingly, fine recrystallized grains are included in the material, and the material can have a mixed structure with a high proportion of γ phase. Thereby, strength and ductility with good balance are imparted to the obtained stainless steel plate, and both high flatness and low residual stress can be achieved. FIG. 2 shows a graph showing an example of the relationship between the temperature of the material and the 0.2% proof stress value of the material. The tension is determined and applied according to FIG.

As a method for refining inclusions, it is preferable to take measures for enhancing floating separation of coarse inclusions during melting. This includes a method of floating and separating coarse inclusions by extending the heating and holding time of the molten metal. In addition, a method of finely crushing coarse inclusions by performing the first cold rolling step (S1) and the second cold rolling step (S2) with a small-diameter roll can be exemplified. Further, the above two methods may be combined as long as the compound having a maximum diameter of 20 μm or more contained in the stainless steel plate can be reduced to 30 or less per 5 g of the mass of the stainless steel plate.
Furthermore, temper rolling can be performed after the second annealing for the purpose of increasing the strength, etc., as long as the present invention can maintain the effect of inclusion distribution and mixed structure that expresses high performance. .

  The stainless steel plate for parts of the present invention can be manufactured by such a method for manufacturing a stainless steel plate for parts. That is, it is possible to manufacture and provide a stainless steel plate that can improve workability (formability, etching property) and fatigue properties while making the above various properties excellent. And according to this manufacturing method, it is possible to supply the stainless steel plate of the said invention cheaply and industrially stably.

  Next, the embodiment will be described in more detail. However, the present invention is not limited to this embodiment. In the examples, a stainless steel plate corresponding to the present invention and a stainless steel plate not corresponding to the present invention were manufactured and subjected to various evaluations.

(I) Production of test material Table 1 shows the composition of the test material. Among the components, those outside the scope of the present invention are marked with “*” with respect to their content numbers.

  A stainless steel plate was manufactured according to each manufacturing condition for each material having the composition shown in Tables 1 to 1. Table 2 shows the main conditions in the manufacturing process.

  The manufacturing method will be described in detail with reference to Table 2. In Table 2, "*" was attached | subjected about what was outside the scope of the present invention. The process up to cold rolling is common in each manufacturing condition. Specifically, a small ingot was melted and subjected to cutting, hot rolling, annealing, and descaling (acid cleaning). In Table 2, No. 1-No. 16, no. 18, no. 20-No. 22, no. 26-No. About the example shown by 32, as a countermeasure against inclusion refinement, the heating and holding time of the molten metal was extended in order to strengthen floating separation of coarse inclusions during melting.

  For the material thus obtained, No. 1-No. For the steel material shown in No. 26, after partly adjusting the plate thickness by cutting and pickling, the first cold rolling and annealing were performed, and the second cold rolling and second annealing were performed under the conditions shown in Table 2. It was. The plate thickness was finally 0.2 mm. Here, no. 10 and no. About the example shown by 17, the small diameter work roll of diameter 60mm was used with respect to the diameter 200mm work roll which used the roll diameter used for cold rolling as a countermeasure for refinement | miniaturization of inclusions.

  On the other hand, no. In the examples of No. 27 to No. 32, temper rolling was performed to a thickness of 0.2 mm as shown in Table 2, and each hardness specification defined in JIS G 4313 was adopted. After that, shape correction with a tension leveler, 500 ° C. heating, and strain relief annealing with holding for 300 seconds were performed. A work roll having a diameter of 200 mm was used during cold rolling.

  Test pieces were collected from the thin plate having a thickness of 0.2 mm obtained as described above, and various characteristics were investigated and compared.

(Ii) Evaluation items and evaluation methods Evaluation items and evaluation methods thereof will be described below.
Compound distribution: First, 5 g of a sample was collected, and the base material portion was removed by corrosion with a 10% bromine methanol solution. Thereafter, the residue was extracted through a filter having a predetermined pore size, and the residue was observed using a scanning electron microscope (SEM) to obtain a total number of compounds having a maximum diameter of 20 μm or more.

  Crystal grain size: The structure after embedding, polishing, and etching was observed with an optical microscope and SEM for a cross section parallel to the rolling direction (RD) of the sample. In addition, a thin film was prepared, and the tissue was observed using a transmission electron microscope (TEM). Then, a photograph of an average structure was taken in each, and the crystal grain size was measured from the photograph. This also determined whether the tissue was a mixed tissue.

  The crystal grain size is No. 1-No. No. 26, the value of recrystallized grains after temper annealing, No. 26 27-No. About 32, the value after a 2nd annealing process is shown. Here, no. 27-No. Since No. 32 is deformed by temper rolling and becomes expanded grains, it is shown in parentheses in Table 3. It was also assumed that there was no change in particle size due to strain relief annealing.

  γ phase ratio: The diffraction pattern was measured on the plate surface using an X-ray diffractometer, and the ratio of γ phase and α 'phase was calculated from the integrated intensity ratio of each phase peak.

  Hardness: The plate surface was measured with a load of 9.8 N using a micro-Vickers hardness meter.

  Elongation: A JIS-3B test piece collected in parallel with the rolling direction (RD) was measured using an Instron type tester.

Surface roughness: R.I. D. The maximum height (Ry) of the surface roughness was measured using a laser microscope on the surface of the outer periphery of the strip-shaped specimen taken perpendicularly to the bending outer periphery before and after the right angle bending at a bending radius of 2 mm.
Increase rate (%) = 100 × (Ry after bending−Ry before processing) / (Ry before processing)
It was evaluated by.

  Fatigue characteristics: Using a double swing type plane bending tester, the fatigue limit (the upper limit value of the stress that can withstand 107 repeated bendings) in a material that has not been bent was clarified. Next, the test piece having the above surface roughness for measurement bending was subjected to repeated bending at a stress of 90% of the fatigue limit of the material, and the presence or absence of cracks after 107 repeated bendings was investigated. The case where it broke was evaluated as x, and the case where it did not crack was evaluated as o.

Plate warpage: In this example, the flatness was evaluated by plate warpage. The method is described in R.T. before and after temper annealing or shape correction + strain relief annealing. D. Measure the height of the lifted warp by suspending visually about a 500 mm long test piece collected in parallel with
Reduction rate (%) = 100 × (warp after treatment−warp before treatment) / warp before treatment.

Residual stress: For test specimens collected before and after temper annealing or shape correction + strain relief annealing, the R. D. Measure the residual stress at
Reduction rate (%) = 100 × (post-treatment stress−pre-treatment stress) / pre-treatment stress.

(Iii) Results Next, the results will be described. First, the results of the structure and structure of the stainless steel plate obtained will be described. Table 3 shows the results.

  As can be seen from Tables 2 and 3, No. 1 satisfying the conditions of the production method of the present invention. 1-No. Regarding No. 17, the number of compounds having a maximum diameter of 20 μm or more was 30 or less, and a mixed tissue could be obtained. On the other hand, no. 18-No. In No. 32, there is a problem that the number of compounds having a maximum diameter of 20 μm or more is 30 or more, or the structure does not become a mixed structure, and the effect of the production method of the present invention is remarkably exhibited.

  Next, various characteristics of the obtained stainless steel plate will be described. Table 4 shows the results.

  Furthermore, the relationship between hardness and elongation based on the results of this example is shown in FIG. As can be seen from Table 4 and FIG. 1-No. No. 17 is a comparative example of No. 17. 18-No. Higher strength and higher ductility than any of 32.

  Further, in each of the examples of the present invention, the increase rate of the maximum value of the surface roughness after bending is 60% or less, and the improvement of the moldability is exhibited by the progress of uniform deformation. FIG. 4 shows a photograph of the surface before and after bending and the surface roughness (Ry) at that time. Specifically, the invention example (No. 4) and the comparative example (No. 28) are shown for a flat plate, a bending radius of 2 mm, and a bending radius of 0.5 mm. The effect of the present invention can also be seen from these photographs and the value of Ry. In particular, in the case of a flat plate, all the stainless steel plates have almost the same surface roughness, but when bending is performed, a large difference appears in the surface roughness.

  Furthermore, in Table 4, the bending fatigue characteristics of the present invention are also good. Thereby, excellent fatigue characteristics can be maintained even after bending. That is, by developing the compound distribution inherent in addition to the mixed structure, uniform deformation progresses and defects that occur during bending are reduced. Thereby, it was considered that excellent formability was exhibited and high fatigue strength could be maintained.

  On the other hand, regarding the etching property, the processed surface has a tendency that the maximum value of the surface roughness is reduced and defects such as etching pits are reduced, and the processed surface tends to be smoothed compared to before processing. That is, according to the present invention, workability including etching property can be improved, and high fatigue strength can be maintained even in a machined part.

  Furthermore, the rate of increase in sheet warpage and residual stress was small, and the residual stress decreased by 70% or more. Therefore, in the present invention, a significant effect is recognized with respect to such characteristics.

  In the examples of the present invention, no. 2, no. 11 and no. In No. 12, since the temper annealing temperature is relatively high, the recrystallized grain size exceeds 10 μm. No. 7, no. For No. 8, since the applied tension exceeds 40% of the 0.2% proof stress, the ratio of the γ phase of the mixed structure becomes smaller than 70%. Thereby, although the stainless steel plate superior to a comparative example can be obtained, it exists in the tendency for the balance of intensity | strength and ductility to be inferior in the example of this invention. About these, No. 2, no. 11 and no. For No. 12, no. 14, no. 16, and no. As shown in FIG. 17, the addition of Nb, Ti, and V can suppress grain growth, which can be further improved. No. 7, no. No. 8 is No. As shown in FIG. 10, it can be improved by reducing the applied tension.

  No. in which measures for inclusion miniaturization were implemented. 1-No. 18, no. 20-No. 22, no. 26-No. 32, the number of inclusions having a maximum diameter of 20 μm or more is within the scope of the present invention, and in particular, No. 32 using floating of inclusions and a small diameter work roll. No. 10 shows the balance between the best strength and ductility and the workability among the examples of the present invention.

  On the other hand, as described above, the comparative example is inferior in the balance between strength and ductility compared to the inventive example. Specifically, no. 18-No. No. 21 is the content of the component, and the Md value falls within the scope of the present invention. 18 and no. In No. 19, 30 or more compounds having a maximum diameter of 20 μm or more were generated due to insufficient rolling reduction. As a result, good characteristics cannot be obtained due to the non-formation of the mixed structure. No. 20 and no. In No. 21, the temper annealing temperature was outside the range of the production method of the present invention, so a mixed structure was not formed, and both workability and fatigue characteristics were equal to or lower than those of the conventional material. Also in other comparative examples, the material does not satisfy the required composition and the performance is not improved.

  Furthermore, no. Table 5 shows the result of the characteristic investigation of the material obtained by subjecting the material 2 to temper rolling at a rolling reduction of 10% and 20%. In Table 5, no. 2-a is No. No. 2 was subjected to temper rolling at a rolling reduction of 10%. 2-b is the case of a reduction rate of 20%. As a result, it is confirmed that the same material maintains excellent characteristics even after temper rolling.

  Although the present invention has been described with reference to the most practical and preferred embodiments at the present time, the present invention is not limited to the embodiments disclosed herein. The present invention can be modified as appropriate without departing from the scope or spirit of the invention that can be read from the claims and the entire specification, and a stainless steel sheet for parts and a method for producing the same are also included in the technical scope of the present invention. Must be understood as being.

[0007]
This is because the reverse transformation of is controlled by the tension during temper annealing. Since the softening is moderated by the application of the tension, it is considered that the increase in the tension suppresses the reverse transformation and increases the amount of α ′ (processing induced martensite) remaining. That is, the metal structure of stainless steel can be controlled by the tension.
[0022]
However, on the other hand, it was found that when the tension was excessive, the γ phase in the non-recrystallized portion was transformed into the α ′ phase during cooling. This is presumably because, in addition to the processing strain in which the γ phase in the non-recrystallized portion remains, a martensitic transformation (α ′) induced by processing occurs at a predetermined temperature or lower during cooling due to the influence of tension. Therefore, the tension to be applied must be performed within a predetermined range in consideration of reverse transformation.
[0023]
(D) As for the production method, the final cold rolling can pulverize and refine the compound by increasing the reduction ratio. This is one of the advantages of making the performance adjustment a separate process (temper annealing), and in temper rolling, implementation at a predetermined processing rate is inevitable for performance adjustment.
[0024]
The present invention will be described below.
[0025]
In the invention described in claim 1, C is 0.01 to 0.08 mass%, Si is 0.1 to 2.0 mass%, Mn when the whole stainless steel is 100 mass%. 3.0% by mass or less, Cr 10.0 to 20.0% by mass, Ni 3.0 to 12.0% by mass, N 0.02 to 0.24% by mass, And the formula Md = 500-458 (C + N) -9 (Si + Mn) -14Cr-20Ni in which the value of the mass% of each contained component is substituted.
The compound having a chemical composition in which the Md value represented by the formula 0 to 80 is satisfied, and the balance is an inevitable impurity, and the maximum diameter is 20 μm or more among the compounds formed by the respective components, the inherent amount of the compound is stainless steel. By providing a stainless steel plate for parts, the number of which is 30 or less per 5 g of steel mass, and the metal structure of the entire stainless steel is a mixed structure of recrystallized grains and non-recrystallized parts. Resolve.
[0026]
In the invention described in claim 2, C is 0.01 to 0.08 mass%, Si is 0.1 to 2.0 mass%, Mn when the whole stainless steel is 100 mass%. 3.0 mass% or less, Cr 10.0-20.0 mass%, Ni 3.0-12.0 mass%, N 0.02-0.24 mass%, and Nb, Ti, V Each component is contained at 0.5% by mass or less of at least one selected from

[0008]
Formula in which the value of mass% of each component is substituted Md = 500-458 (C + N) -9 (Si + Mn) -14Cr-20Ni-65Nb-27Ti-61V
The compound having a chemical composition in which the Md value represented by the formula 0 to 80 is satisfied, and the balance is an inevitable impurity, and the maximum diameter is 20 μm or more among the compounds formed by the respective components, the inherent amount of the compound is stainless steel. By providing a stainless steel sheet for parts, the number of which is 30 or less per 5 g of steel mass, and the metal structure of the entire stainless steel is a mixed structure of recrystallized grains and non-recrystallized parts. Resolve.
[0027]
The invention described in claim 3 is characterized in that the average grain size of the recrystallized grains of the stainless steel sheet for parts described in claim 1 or 2 is 10 μm or less.
[0028]
The invention described in claim 4 is characterized in that the mixed structure of the stainless steel sheet for parts described in claim 3 is an austenite phase of 70% by mass or more.
[0029]
In the invention according to claim 5, when the entire stainless steel is 100 mass%, C is 0.01 to 0.08 mass%, Si is 0.1 to 2.0 mass%, Mn 3.0% by mass or less, Cr 10.0 to 20.0% by mass, Ni 3.0 to 12.0% by mass, N 0.02 to 0.24% by mass, And the formula Md = 500-458 (C + N) -9 (Si + Mn) -14Cr-20Ni in which the value of the mass% of each contained component is substituted.
A first cold rolling step (S1) in which a material having a chemical composition in which the Md value represented by the formula 0 to 80 is satisfied and the balance is an inevitable impurity is cold-rolled at least once, and the first cold rolling The first annealing step (S2) arranged after the first cold rolling step in combination with the step, and the final rolling provided on the subsequent step side of the first annealing step, the rolling reduction is 20% or more, And the 2nd cold rolling process (S3) from which the total reduction with 1st cold rolling will be 60% or more, and hold | maintain the said raw material after a 2nd cold rolling process at 650-1000 degreeC for 300 second or less And a second annealing step (S4) in which the material is tempered by applying a tension at 0.2% proof stress or less of the material at the held temperature to enhance the floating separation of coarse inclusions during the melting of the material. Or at least one of using a small diameter roll for the final cold rolling Comprising a step of refining coarse inclusions, wherein the amount of the compound having a maximum diameter of 20 μm or more among the compounds formed by each component is 30 or less per 5 g of stainless steel mass The above-mentioned problems are solved by a method for manufacturing a stainless steel sheet for parts.
[0030]
In the invention according to claim 6, when the entire stainless steel is 100 mass%, C is 0.01 to 0.08 mass%, Si is 0.1 to 2.0 mass%, Mn 3.0 mass% or less, Cr 10.0-20.0 mass%, Ni 3.0-12.0 mass%, N 0.02-0.24 mass%, and Nb, Ti, V Each component is contained at 0.5% by mass or less of at least one selected from

[0009]
Formula in which the value of mass% of each component is substituted Md = 500-458 (C + N) -9 (Si + Mn) -14Cr-20Ni-65Nb-27Ti-61V
A first cold rolling step (S1) in which a material having a chemical composition in which the Md value represented by the formula 0 to 80 is satisfied and the balance is an inevitable impurity is cold-rolled at least once, and the first cold rolling The first annealing step (S2) arranged after the first cold rolling step in combination with the step, and the final rolling provided on the subsequent step side of the first annealing step, the rolling reduction is 20% or more, And the 2nd cold rolling process (S3) from which the total reduction with 1st cold rolling will be 60% or more, and the raw material after a 2nd cold rolling process are hold | maintained at 650-1000 degreeC for 300 seconds or less. And a second annealing step (S4) in which the material is tempered by applying a tension at 0.2% proof stress or less of the material at the held temperature to enhance the floating separation of coarse inclusions during the melting of the material. Or at least one of using a small diameter roll for the final cold rolling, The inclusions of the compound having a maximum diameter of 20 μm or more among the compounds formed by the respective components are 30 or less per 5 g of the mass of the stainless steel. The said subject is solved by providing the stainless steel plate manufacturing method for components.
[0031]
The invention according to claim 7 is the material at a temperature at which the tension in the second annealing step of the method for manufacturing a stainless steel sheet for parts according to claim 5 or 6 is maintained. It is characterized by being 40% or less of the% yield strength.
[0032]
The invention described in claim 8 further includes temper rolling after the second annealing step (S4) in the method for manufacturing a stainless steel plate for parts according to any one of claims 5 to 7. It is characterized by giving.
Effects of the Invention [0033]
ADVANTAGE OF THE INVENTION According to this invention, the stainless steel plate and its manufacturing method which can manufacture a wide variety of components accurately and with high reliability can be provided. In particular, in the present invention, it is possible to provide a stainless steel plate that is excellent in formability and fatigue characteristics after forming and has high reliability at low cost and industrially stably. In addition, in response to recent environmental problems, it is possible to further promote the effective use of resources by reducing the size and weight.
BRIEF DESCRIPTION OF THE DRAWINGS [0034]
FIG. 1 is a diagram for explaining one aspect of the flow of the production method of the present invention.
FIG. 2 is a graph showing an example of the relationship between material temperature and 0.2% proof stress.
FIG. 3 is a graph showing the relationship between hardness and elongation of a stainless steel plate prepared based on the results obtained in this example.
[FIG. 4] No. of this example. 4 and no. 28 shows an enlarged surface of the bent portion.

Claims (8)

When the entire stainless steel is 100 mass%, C is 0.01 to 0.08 mass%, Si is 0.1 to 2.0 mass%, Mn is 3.0 mass% or less, and Cr is 10. 0 to 20.0 mass%, Ni is 3.0 to 12.0 mass%, N is 0.02 to 0.24 mass%, and each component is contained, and the mass% of each of the contained components Md = 500-458 (C + N) -9 (Si + Mn) -14Cr-20Ni
The Md value represented by the formula has a chemical composition in which 0 to 80 is satisfied, and the balance is an inevitable impurity,
Among the compounds formed by the respective components, the intrinsic amount of the compound having a maximum diameter of 20 μm or more is 30 or less per 5 g of the mass of the stainless steel, and the metal structure of the entire stainless steel is recrystallized grains and Stainless steel sheet for parts, which is a mixed structure of non-recrystallized parts. When the entire stainless steel is 100 mass%, C is 0.01 to 0.08 mass%, Si is 0.1 to 2.0 mass%, Mn is 3.0 mass% or less, and Cr is 10. 0 to 20.0 mass%, Ni is 3.0 to 12.0 mass%, N is 0.02 to 0.24 mass%, and one or more selected from Nb, Ti, and V is 0.5 mass% In the following formula, each component is contained, and the mass% value of each of the contained components is substituted. Md = 500-458 (C + N) -9 (Si + Mn) -14Cr-20Ni-65Nb-27Ti-61V
The Md value represented by the formula has a chemical composition in which 0 to 80 is satisfied, and the balance is an inevitable impurity,
Among the compounds formed by the respective components, the inherent amount of the compound having a maximum diameter of 20 μm or more is 30 or less per 5 g of the mass of the stainless steel, and the metal structure of the entire stainless steel is recrystallized grains. Stainless steel sheet for parts, which is a mixed structure of non-recrystallized parts.   3. The stainless steel plate for parts according to claim 1, wherein an average grain size of the recrystallized grains is 10 μm or less.   The stainless steel sheet for parts according to claim 3, wherein the mixed structure is an austenite phase of 70 mass% or more. When the entire stainless steel is 100 mass%, C is 0.01 to 0.08 mass%, Si is 0.1 to 2.0 mass%, Mn is 3.0 mass% or less, and Cr is 10. 0 to 20.0 mass%, Ni is 3.0 to 12.0 mass%, N is 0.02 to 0.24 mass%, and each component is contained, and the mass% of each of the contained components Md = 500-458 (C + N) -9 (Si + Mn) -14Cr-20Ni
A first cold rolling step of cold rolling a material having a chemical composition with a Md value represented by 0 to 80 and the balance being an inevitable impurity, and the first cold rolling step, A first annealing step arranged after the first cold rolling step, and a final rolling provided on the subsequent step side of the first annealing step, and a reduction rate of 20% or more and the first rolling step The second cold rolling step in which the total rolling reduction with cold rolling is 60% or more, and the material after the second cold rolling step is held at 650 to 1000 ° C. for 300 seconds or less, and the holding And a second annealing step in which a tension is applied at a temperature equal to or less than 0.2% proof stress of the material at a given temperature to produce a stainless steel sheet for parts. When the entire stainless steel is 100 mass%, C is 0.01 to 0.08 mass%, Si is 0.1 to 2.0 mass%, Mn is 3.0 mass% or less, and Cr is 10. 0 to 20.0 mass%, Ni is 3.0 to 12.0 mass%, N is 0.02 to 0.24 mass%, and one or more selected from Nb, Ti, and V is 0.5 mass% Formula Md = 500−458 (C + N) −9 (Si + Mn) −14Cr−20Ni−65Nb−27Ti−61V containing each component and substituting the value of mass% of each component contained below.
A first cold rolling step of cold rolling a material having a chemical composition with a Md value represented by 0 to 80 and the balance being an inevitable impurity, and the first cold rolling step, A first annealing step arranged after the first cold rolling step, and a final rolling provided on the subsequent step side of the first annealing step, and a reduction rate of 20% or more and the first rolling step The second cold rolling step in which the total rolling reduction with cold rolling is 60% or more, and the material after the second cold rolling step is held at 650 to 1000 ° C. for 300 seconds or less, and the holding And a second annealing step in which a tension is applied at a temperature equal to or less than 0.2% proof stress of the material at a given temperature to produce a stainless steel sheet for parts.   The component according to claim 5 or 6, wherein the tension in the second annealing step is 40% or less of the 0.2% proof stress of the material at the held temperature. Stainless steel sheet manufacturing method.   The method for producing a stainless steel sheet for parts according to any one of claims 5 to 7, further comprising temper rolling after the second annealing step.

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