JP5197113B2 - Stainless steel press-molded body and production method - Google Patents

Description

  The present invention relates to an intermediate product press-molded body made of an austenitic stainless steel sheet having a property of generating work-induced martensite by processing, a high-strength press-molded body formed by aging treatment thereof, and a method for producing the same. . This high-strength press-molded body is suitable for case members and hinge parts of cameras, mobile phones, notebook computers, portable music devices, and the like.

  Conventionally, martensitic stainless steels such as SUS410 and SUS420J2 and high C-type austenitic stainless steels such as SUS301 with high work hardening have been used for press-formed products made of stainless steel that require high strength. However, martensitic stainless steel needs to be subjected to a quenching treatment after press forming, and has a problem that productivity is poor due to a high quenching temperature, and a dimensional change during quenching is large. On the other hand, high C type austenitic stainless steel with high work hardening is a material that hardens the material by temper rolling at the stage of steel sheet. It is difficult to make large molded products. It is also difficult to obtain high dimensional accuracy.

JP-A-56-77364 JP-A-4-168227 JP 2000-63996 A

  The present invention intends to provide a high strength stainless steel press-formed body having a hardened portion of 350 HV or higher in at least a processed portion using a steel plate material with a small load on a press die.

As a result of research, the inventors have adjusted the easiness of forming work-induced martensite and reduced the C content in the austenitic stainless steel containing Cu.
(I) At the material steel plate stage, it is relatively soft and reduces the load on the press die.
(Ii) After press molding, a portion where at least 10% by volume or more of processing-induced martensite is present can be formed in a processed portion requiring high strength,
(Iii) By performing an aging treatment thereafter, it becomes possible to remarkably increase the strength of a portion where 10% by volume or more of the processing-induced martensite exists,
I found. The present invention has been completed based on such findings.

That is, in the present invention, by mass, C: 0.03% or less, Si: 0.5-2%, Mn: 0.5-2%, Ni: 6-10%, Cr: 15-18%, Cu : 1 to 3.5%, N: 0.03% or less, optionally containing Mo: 3% or less, consisting of the balance Fe and unavoidable impurities, Md value of the following formula (1) is 10 It is a press-molded body made of a steel plate having a composition of ~ 30, and has a portion where the processing induced martensite amount is 10% by volume or more and the cross-sectional hardness of the wall thickness central portion is less than 350 HV in the pressed portion. An intermediate stainless steel press-molded body that has not yet been aged is provided.
Md = 551-462 (C + N) -9.2 Si-8.1 Mn-29 (Ni + Cu) -13.7Cr-18.5Mo (1)

  This press-formed product of the intermediate product has a property that can be increased in strength by subjecting it to an aging treatment thereafter. The content (% by mass) of each element is substituted for each element symbol in the formula (1). In steel containing no Mo, 0 (zero) is substituted into the Mo position in the equation (1). The press-formed body is a processed product obtained by imparting plastic deformation by press processing, and has been subjected to press processing other than punching (shear processing) such as drawing or bending. Of course, you may have a punching (shear process) part in part. The amount of processing-induced martensite can be determined by a magnetic measurement method using a ferrite scope. The press working part is a part to which plastic deformation is applied by pressing (excluding a hardened part in the vicinity of the shear surface in the case of having a shearing part).

  Further, in the present invention, a press-formed body made of a steel plate having the above composition, wherein a portion where the work-induced martensite amount is 10% by volume or more and the cross-sectional hardness of the wall thickness central part is 350 HV or more is used as the pressed part. And a high-strength stainless steel press-formed body in which an aged Cu-rich phase is dispersed in martensite.

Furthermore, in the present invention, as a method for producing such a high-strength stainless steel press-formed body, the matrix has an austenite single-phase structure or a multiphase structure of “austenite + 25 volume% or less work-induced martensite”. By applying press forming to the adjusted steel sheet, "the portion where the cross-sectional hardness of the central wall portion is less than 350 HV and the amount of work-induced martensite is at least 10% by volume or more" A step of making a press-formed body having,
A step of subjecting the press-molded body to an aging treatment under a condition that an aging temperature T (K) and an aging time t (h) in a temperature range of 400 to 500 ° C. satisfy the following formula (2):
There is provided a method for producing a high-strength stainless steel press-formed body having the following.
13000 ≦ T (logt + 20) ≦ 16500 (2)

  According to the present invention, since a relatively soft material steel plate can be used for press forming, it is possible to avoid an increase in load and a decrease in service life of a press die that are likely to be a problem when producing a high-strength stainless steel press product. It is also effective in improving dimensional accuracy. In addition, by subjecting the press-formed product to an aging treatment, remarkable hardening can be achieved particularly in a processed portion requiring high hardness. Since the aging treatment has a lower heating temperature than the quenching treatment and does not require a rapid cooling treatment, the process load after press working can be reduced. Therefore, the present invention is more suitable for mass production of high-strength stainless steel press-formed products.

<Chemical composition>
In the present invention, the chemical composition of steel is limited as follows. “%” In the chemical composition means “% by mass” unless otherwise specified.

[C: 0.03% or less]
C has the effect of hardening the work-induced martensite phase. For this reason, in order to improve workability, low C is advantageous. In the present invention, since an excellent age hardening property by Cu described later is used for a portion of the press-molded body that requires high hardness, it is not necessary to increase the C content for the purpose of increasing the strength. As a result of various studies, the C content is limited to 0.03% or less. It can also be limited to less than 0.03%. Such reduction of the C content suppresses the hardening of the work-induced martensite phase, which is advantageous for reducing the load on the press die and improving the dimensional accuracy. In addition, it is advantageous for reducing corrosion resistance after aging treatment.

[Si: 0.5-2%]
Si is effective as a deoxidizer. Moreover, it acts effectively on the induction of the martensite phase by press molding, and it is necessary to contain Si for adjusting the Md point. Further, Si is effective for hardening by aging treatment. As a result of various studies, it is necessary to contain 0.5% or more of Si in order to fully exhibit the hardening action by the aging treatment. However, even if Si is added in a large amount, the curing action is saturated, which is uneconomical. On the other hand, the function as a deoxidizer and the function of adjusting the Md point can be sufficiently exerted in the Si content range of 0.5 to 2%. Accordingly, the Si content is defined as described above.

[Mn: 0.5 to 2%]
Mn is an element that greatly contributes to the stabilization of the austenite phase. In consideration of the balance with elements such as Si, 0.5% or more of Mn content is necessary for stabilizing the austenite phase. However, the purpose can be sufficiently achieved within a content range of 2% or less.

[Ni: 6 to 10%]
Ni is an essential element for obtaining an austenite structure after finish annealing, and at least 6% or more is necessary. However, it is not necessary to add too much, and excessive addition is not preferable because it causes an increase in cost. As a result of various studies, the Ni content may be in the range of 10% or less.

[Cr: 15-18%]
Cr is an essential element for imparting the corrosion resistance required for stainless steel. As a result of various investigations, it is desirable to secure a Cr content of 15% or more in consideration of applications such as case members and hinge parts of cameras, mobile phones, notebook computers, portable music devices, and the like. However, if the Cr content is increased, a δ ferrite phase is likely to be generated, which causes a decrease in hot workability, so the upper limit of the Cr content is limited to 18%.

[Cu: 1 to 3.5%]
Cu precipitates in the martensite phase by aging treatment, and contributes to increasing the strength of the press-formed product. That is, Cu is solid-dissolved in the austenite phase by finish annealing, and the solid solubility limit is lowered in the processing-induced martensite generated during processing, so that it precipitates as a Cu-rich phase in the martensite phase in the subsequent aging treatment. . This Cu-rich phase is a second phase in which Cu is concentrated, and a so-called ε-Cu phase also corresponds to this, but it may be a very fine cluster. Precipitation of such a Cu-rich phase in the martensite phase results in a significant increase in strength. For that purpose, it is necessary to secure a Cu content of 1% or more, and it is more preferably 1.5% or more. However, since excessive Cu content causes a decrease in hot workability, the upper limit of Cu content is limited to 3.5%.

[N: 0.03% or less]
N, like C, leads to hardening of the work-induced martensite phase. As a result of the study, in the present invention, the N content is limited to 0.03% or less.

[Mo: 3% or less]
Mo has the effect of improving corrosion resistance in high Cr steel, and also precipitates during the aging treatment and contributes to high strength. For this reason, in this invention, Mo can be contained as needed. It is more effective to secure a Mo content of 0.04% or more. When it is desired to obtain high corrosion resistance, the content is more preferably 0.5% or more. However, even if Mo is contained excessively, an increase in the above effect cannot be expected and the cost is increased. Therefore, the Mo content is set to 3% or less.

[Md value: 10-30]
The following formula (1) is an index indicating the stability of the austenite phase in the annealed state. That is, as the value of the formula (1) increases, the austenite phase becomes unstable, and a work-induced martensite phase is easily generated.
Md = 551-462 (C + N) -9.2 Si-8.1 Mn-29 (Ni + Cu) -13.7Cr-18.5Mo (1)

  In the present invention, the content of each alloy element is strictly adjusted so that the Md value falls within a narrow range of 10 to 30. If the Md value is less than 10, the austenite phase after finish annealing becomes too stable, and in order to sufficiently secure the amount of work-induced martensite phase generated that greatly contributes to age hardening in the processed part of the press-formed body, It is necessary to use a steel plate material having a considerably high quality rolling rate. In this case, the load on the press mold increases, which is not preferable. On the other hand, if the Md value exceeds 30 and the austenite phase becomes excessively unstable, the amount of work-induced martensite phase in the press-molded product tends to vary, and the properties of the final product also tend to vary. .

《Press-formed body before aging treatment as an intermediate product》
The press-molded body at this stage needs to have a portion where the amount of work-induced martensite is 10% by volume or more in the press-worked portion. As described above, Cu that is supersaturated in the matrix is likely to precipitate in the martensite phase having a lower solid solubility limit when aging treatment is performed in a later step, and in particular, the processing-induced martensite phase is reduced. Harden significantly. The work-induced martensite phase has a slightly different work-hardening characteristic depending on the processing mode such as tension, stretching, deep drawing, bending, etc., even if the amount of the work-induced martensite phase is the same. However, according to the study by the inventors, a part in which a processing induced martensite phase of 10% by volume or more exists in the processed part of the press-molded body, regardless of the processing induced martensite phase generated by any processing mode. If there is, it is possible to bring about remarkable hardening by the later-described aging treatment. For portions where the amount of work-induced martensite is less than 10% by volume, it is difficult to stably obtain significant age hardening by aging treatment. However, in the case of a part using a press-molded body, it is usually not necessary that the whole is significantly hardened, and it is sufficient that only a processed part requiring high strength is sufficiently hardened. Therefore, in the press-formed body which is an intermediate product of the present invention, it is important that at least the processed portion has a portion where the amount of processing-induced martensite is 10% by volume or more.

  Moreover, the press-molded body which is this intermediate product needs to have a portion where the cross-sectional hardness of the central thickness portion is less than 350 HV in the portion where the amount of work-induced martensite is 10% by volume or more. is there. A press-molded body in which all portions where a work-induced martensite phase of 10% by volume or more is generated at a stage of being pressed (before aging treatment) has a hardness of 350 HV or more is, for example, It can be produced by using a steel type with a high C content or using a steel plate with a high temper rolling ratio, but in that case, a heavy load is applied to the press die, resulting in a high cost intermediate. Become a product.

<Press-formed product after aging treatment>
As a press-molded body that has undergone an aging treatment, one having a portion having a cross-sectional hardness of 350 HV or more in the center of the thickness in the press-worked portion is an object. As described above, in a part using a press-molded body, normally only a processed part requiring high strength needs to be significantly hardened. In many applications where high-strength stainless steel press-molded bodies have been used in the past, such as case members and hinge parts for cameras, mobile phones, notebook computers, portable music devices, etc., parts that require high strength The material hardness is desirably 350 HV or more. The high-strength stainless steel press-formed body of the present invention achieves high strength by utilizing precipitation of a Cu-rich phase in the work-induced martensite phase. For this reason, in the press-molded body, the amount of work-induced martensite in a portion cured to 350 HV or more is 10% by volume or more, and an aging-precipitated Cu-rich phase is dispersed in the martensite in that portion. There is a feature.

"Production method"
〔Manufacturing process〕
The above high-strength stainless steel press-formed bodies are made into austenite single-phase structure by subjecting a steel plate (hot rolled steel plate or cold rolled steel plate) with a predetermined thickness to solution treatment, and temper rolling is performed as necessary. It can be obtained by a step of forming a raw steel plate, subjecting the raw steel plate to press forming, and then performing an aging treatment.

[Material steel plate]
As a material steel plate used for press forming, a steel plate having the above-described chemical composition and having a matrix adjusted to austenite single phase structure or a multiphase structure of “austenite + 25% by volume or less work-induced martensite” is used. Depending on the shape of the press-formed body, when using austenite single-phase structure steel sheet, it is not possible to obtain a multiphase structure of “austenite + 10% by volume or more of work-induced martensite” at the site where high strength is required. There is. For example, such a situation tends to occur in a press-molded body obtained by performing a shallow drawing process or a relatively light bending process. Moreover, the case where especially high hardness is requested | required in a press work part, and the case where it is wished to also strengthen parts other than a press work part are assumed. In such a case, it is effective to use a raw steel plate in which a work-induced martensite phase of 10% by volume or more has been generated in advance by temper rolling. How much work-induced martensite phase is produced depends on the composition, the degree of press forming, and the like. The amount of work-induced martensite phase produced can be adjusted by the temper rolling rate. However, if the amount of the work-induced martensite phase at the stage of the raw steel plate exceeds 25% by volume, the load applied to the press die tends to be excessive.

〔Press molding〕
Various conventional methods can be applied to press molding. In press molding, as described above, a press-molded body having, as described above, “a portion where the cross-sectional hardness of the central thickness portion is less than 350 HV and the amount of work-induced martensite is at least 10% by volume or more” It is important to make. Of course, the portion requiring particularly high strength may have a hardness exceeding 350 HV.

[Aging treatment]
After press forming, an aging treatment is performed to disperse and precipitate the Cu-rich phase in the work-induced martensite, thereby obtaining a high-strength stainless steel press-formed body. As a result of various studies, it is effective that the aging temperature is in a temperature range of 400 to 500 ° C. and that the aging temperature T (K) and the aging time t (h) satisfy the following formula (2). If the value of T (logt + 20) is too small, the precipitate size of the Cu-rich phase becomes small, and the effect of sufficiently inhibiting dislocation movement is hardly exhibited. On the other hand, if the value of T (logt + 20) is excessive, Cu-rich phase particles become coarse, dislocations easily bypass the precipitated particles, and the distance between the precipitated particles becomes longer, so that the hardening phenomenon is hardly exhibited. In addition, it is more preferable to set the range satisfying the formula (2) ′ instead of the formula (2).
13000 ≦ T (logt + 20) ≦ 16500 (2)
14000 ≦ T (logt + 20) ≦ 16000 (2) ′

  By performing the aging treatment in an atmosphere capable of nitriding, the surface of the high-strength stainless steel press-molded body can be cured, and further widespread application development is expected.

  The steel shown in Table 1 was melted to obtain a finish annealed material having a thickness of 0.8 mm and having an austenite single phase structure.

A deep drawn cup (a press-formed product of an intermediate product) was produced under the following conditions using a plate material collected from the finish annealing material as a raw steel plate.
Blank diameter: 76 mm, punch diameter: 40 mm, punch shoulder radius: 6 mm, die diameter: 42 mm, die shoulder radius: 6 mm, wrinkle holding force: 1 ton
The deep-drawn cup was subjected to an aging treatment that was held at 450 ° C. for 1 hour in the atmosphere. In this case, the value of T (logt + 20) described above is 14460, which satisfies the expressions (2) and (2) ′.

  The press-molded body sample of the intermediate product and the press-molded body sample after the aging treatment were cut along a plane including the center axis of the cup. FIG. 1 schematically shows a measurement position in the cut section. The hardness at the center of the wall thickness was measured at four locations a, b, c, and d. About the press-molded body sample of the intermediate product, the processing induced martensite amount of the cross section was further measured using a ferrite scope. The value of the processing induced martensite amount was obtained by applying plate thickness correction. The results are shown in Table 2. The amount of processing-induced martensite after aging treatment is equivalent to that before aging treatment (intermediate product).

  The material hardness measured separately was 135 HV for steel A of the subject steel of the present invention and 155 HV for steel B of the comparative steel. As can be seen from Table 2, in both cases of steel A and steel B, the press-worked portion has a portion where the amount of work-induced martensite is 10% by volume and the cross-sectional hardness is 350 HV or less. A 350 HV portion was formed. However, when the steel A, which is the subject steel of the present invention, is used, the work induction of 10% by volume or more after the aging treatment is performed even though the hardness of each measurement point in the intermediate product is lower than in the case of the steel B. Remarkable hardening exceeding B steel was recognized in the locations of b, c, and d where the martensite phase was generated. Further, in the case of B steel, a hardened portion exceeding 400 HV is generated in the intermediate product, which is not preferable because it imposes a heavy load on the press mold and leads to a decrease in the mold life.

Using the same A steel and B steel as in Example 1, a raw steel plate having a thickness of 1 mm prepared by 31% temper rolling after finish annealing was prepared. The amount of work-induced martensite in the material steel plate was A steel: 8% by volume and B steel: 5% by volume.
Using these steel sheets, an attempt was made to produce a deep drawn cup (intermediate product press-formed product) under the following conditions.
Blank diameter: 80 mm, punch diameter: 40 mm, punch shoulder radius: 6 mm, die diameter: 42.5 mm, die shoulder radius: 6 mm, wrinkle holding force: 1 ton

As a result, the steel A was able to be deep-drawn satisfactorily, but the steel B was broken before it was drawn, so the drawing process was stopped halfway.
A deep drawn cup of steel A was subjected to an aging treatment under the same conditions as in Example 1.
About the press-molded body sample of the intermediate product of A steel and the press-molded body sample after the aging treatment, the same measurement as in Example 1 was performed. The measurement positions are a, b, c, and d in FIG. The results are shown in Table 3.

  As can be seen from Table 3, by using a temper rolled material as the raw steel plate, even at the bottom of the cup (position a) where the degree of processing in press molding is small, it is hardened to a hardness of 350 HV or higher after aging treatment. It was possible. The intermediate product has a portion with a cross-sectional hardness of 350 HV or less in the press-processed portion, and since there is no hardened portion exceeding 400 HV, the load on the press mold does not increase significantly, and the cost is low. It is thought that mass production is possible.

It can be realized in Examples 1 and 2 by using the same steel A as in Example 1 and using a 2 mm-thick finish annealed material having an austenite single-phase structure as a raw steel sheet and performing drawing processing including an overhanging element. Attempted significant cure at the bottom of the pressed cup that was not present. In drawing, the material steel plate was drawn to a drawing height of 25 mm under the following conditions to obtain a press-formed product of an intermediate product.
Blank diameter: 80 mm, punch diameter: 27.5 mm, punch shoulder radius: 5 mm, die diameter: 32.5 mm, die shoulder radius: 6 mm, wrinkle holding force: 0.5 ton, drawing height: 25 mm

The obtained intermediate product, a press-molded product, was subjected to an aging treatment under the same conditions as in Example 1.
The press-molded body sample of the intermediate product and the press-molded body sample after the aging treatment were cut along a plane including the center axis of the cup. FIG. 2 schematically shows the measurement position in the cut section. The same measurement as in Example 1 was performed at four locations a, b, c, and d. The results are shown in Table 4.

  As can be seen from Table 4, significant curing was achieved at the bottom of the cup. Even in this case, the intermediate product has a portion having a cross-sectional hardness of 350 HV or less in the press-processed portion, and since there is no hardened portion exceeding 400 HV, the load on the press die is significantly increased. It is considered that mass production is possible at low cost.

  The steel shown in Table 5 was melted in a vacuum melting furnace, the slab was hot forged to a thickness of 40 mm, hot rolled to a hot rolled steel plate with a thickness of 3.6 mm, annealed and pickled, A cold rolled steel sheet having a thickness of 0.8 mm was formed by cold rolling, finish annealing was performed at 1150 ° C., and pickling was performed to obtain a raw steel sheet having a thickness of 0.8 mm having an austenite single phase structure.

Using these material steel plates, deep drawn cups (press-formed bodies of intermediate products) were produced under the following conditions.
Blank diameter: 76 mm, punch diameter: 40 mm, punch shoulder radius: 6 mm, die diameter: 42 mm, die shoulder radius: 6 mm, wrinkle holding force: 1 ton

The obtained intermediate product, a press-molded product, was subjected to an aging treatment under the same conditions as in Example 1.
The same measurement as in Example 1 was performed for the press-formed sample of the intermediate product and the press-formed sample after the aging treatment. The measurement position was a section from a to d in FIG. 1 and examined in detail at intervals of about 2.5 mm.

As a result, except for steel Nos. 23 and 24, both of the intermediate products have a portion with a work-induced martensite amount of 10% by volume and a cross-sectional hardness of 350 HV or less in the press working part. A 350 HV portion was formed. However, since the comparative steel No. 21 has too high C content and No. 22 has too high N content, these are markedly hardened in the work-induced martensite phase, and the cross-sectional hardness of the intermediate product exceeds 400 HV. Part occurred. In No. 25, since the Md value was too high, a large amount of processing-induced martensite was generated, and a portion having a cross-sectional hardness exceeding 400 HV was generated in the intermediate product. In this way, the intermediate product having a hardened portion exceeding 400 HV is not preferable because the load on the press die is large and the life of the die is shortened. No. 23 was insufficiently cured after the aging treatment because the Cu content was too low. In No. 24, since the Md value was too low, the amount of work-induced martensite phase produced was insufficient, and high strength was not achieved.
Table 6 illustrates the result at a position 2.5 mm from b between b and c in FIG. 1 for reference.

Sectional drawing which showed typically the measurement position in the press molding body (deep drawing cup) of Example 1. FIG. Sectional drawing which showed typically the measurement position in the press-molding body of Example 3 (drawing cup for overhanging).

Claims (7)

By mass%, C: 0.03% or less, Si: 0.5-2%, Mn: 0.5-2%, Ni: 6-10%, Cr: 15-18%, Cu: 1-3. 5%, N: 0.03% or less, balance Fe and inevitable impurities, a press-molded body made of a steel sheet having a composition having an Md value of 10 to 30 in the following formula (1), An intermediate product stainless steel press-molded body that has a martensite content of 10% by volume or more and has a portion having a cross-sectional hardness of less than 350 HV at the center of the thickness in the press-worked portion yet to be aged.
Md = 551-462 (C + N) -9.2 Si-8.1 Mn-29 (Ni + Cu) -13.7Cr-18.5Mo (1)   Furthermore, the stainless steel press-molded body of the intermediate product according to claim 1, which has a composition containing Mo: 3% or less. By mass%, C: 0.03% or less, Si: 0.5-2%, Mn: 0.5-2%, Ni: 6-10%, Cr: 15-18%, Cu: 1-3. 5%, N: 0.03% or less, balance Fe and inevitable impurities, a press-molded body made of a steel sheet having a composition having an Md value of 10 to 30 in the following formula (1), High-strength stainless steel with a martensite content of 10% by volume or more and a section with a cross-sectional hardness of 350 HV or more at the center of the wall thickness in the press-worked part, in which aging-precipitated Cu-rich phase is dispersed. Steel press-molded body.
Md = 551-462 (C + N) -9.2 Si-8.1 Mn-29 (Ni + Cu) -13.7Cr-18.5Mo (1)   Furthermore, the high-strength stainless steel press-formed body according to claim 3, which has a composition containing Mo: 3% or less. By mass%, C: 0.03% or less, Si: 0.5-2%, Mn: 0.5-2%, Ni: 6-10%, Cr: 15-18%, Cu: 1-3. 5%, N: 0.03% or less, balance Fe and inevitable impurities, having a composition in which the Md value of the following formula (1) is 10 to 30, and the matrix is an austenite single phase structure or “austenite + 10 volume” By applying press forming to a steel sheet adjusted to a multiphase structure of “working-induced martensite of less than 10%”, the work-induced martensite content is 10% by volume or more and the cross-sectional hardness at the center of the wall is less than 350 HV A process of making a press-molded body having a part that is
A step of subjecting the press-molded body to an aging treatment under a condition that an aging temperature T (K) and an aging time t (h) in a temperature range of 400 to 500 ° C. satisfy the following formula (2):
A method for producing a high-strength stainless steel press-formed body having:
Md = 551-462 (C + N) -9.2 Si-8.1 Mn-29 (Ni + Cu) -13.7Cr-18.5Mo (1)
13000 ≦ T (logt + 20) ≦ 16500 (2) By mass%, C: 0.03% or less, Si: 0.5-2%, Mn: 0.5-2%, Ni: 6-10%, Cr: 15-18%, Cu: 1-3. 5%, N: 0.03% or less, balance Fe and inevitable impurities, and has a composition in which the Md value of the following formula (1) is 10-30, “working induction of austenite + more than 10-25% by volume A step of producing a press-molded body having a press-processed portion having a cross-sectional hardness of less than 350 HV at the thickness center by applying press molding to a steel sheet adjusted to a multi-phase structure of “martensite”;
A step of subjecting the press-molded body to an aging treatment under a condition that an aging temperature T (K) and an aging time t (h) in a temperature range of 400 to 500 ° C. satisfy the following formula (2):
A method for producing a high-strength stainless steel press-formed body having:
Md = 551-462 (C + N) -9.2 Si-8.1 Mn-29 (Ni + Cu) -13.7Cr-18.5Mo (1)
13000 ≦ T (logt + 20) ≦ 16500 (2)   The method for producing a high-strength stainless steel press-formed body according to claim 5 or 6, wherein the steel sheet further contains Mo: 3% or less.

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