JP4018825B2 - Austenitic stainless steel for press forming - Google Patents

Description

【００２５】
・張出し性試験−エリクセン値
「ＪＩＳ Ｚ ２２４７」に規定されているエリクセン試験Ｂ法により、エリクセン値を求めた。
・深絞り性試験−限界絞り比（ＬＤＲ）
４０ｍｍφ平頭ポンチによる円筒深絞り試験を行い、その限界絞り比（ＬＤＲ）が２．２０を超えるものを深絞り性に優れるとして○、２．１０〜２．２０のものを深絞り性にやや劣るとして△、２．１０未満のものを深絞り性に劣るとして×と評価した。
【００２６】
・バーリング加工性試験−穴広げ率
まず、供試材に打ち抜きによって１０ｍｍφの穴を空け、次いで、この穴を頂角３０度の円錐ポンチで押し広げ、穴の縁に生じた亀裂が板厚を貫通したときの穴の径を測定し、次式によって穴広げ率を求めた。
穴広げ率（％）＝１００×（Ｄ１−Ｄ０）／Ｄ０
（Ｄ０：初期の穴の径（＝１０ｍｍφ）、Ｄ１：試験後の穴の径）
・耐時期割れ性試験
１００ｍｍφの供試材に対し、第１絞り：５０ｍｍφ、第２絞り：４５ｍｍ、第３絞り：３８ｍｍφの平頭ポンチを用いて多段絞りを施した後、室温で２００時間放置した後の割れの発生の有無を観察した。割れの発生がない場合を○、割れの発生がある場合を×と評価した。
以上の試験結果を、表２に示す。
【００２７】
【表２】

【００２８】
表２から明らかなように、本発明鋼Ａ１〜Ａ９は、いずれも張出し性、深絞り性、バーリング加工性（以下、これらを成形性と総称する）および耐時期割れ性に優れている。一方、各比較鋼は、本発明で規定される成分組成のうちのいずれかが本発明外であり、成形性および耐時期割れ性のうちの１つ以上の性質が劣っていた。
【００２９】
ここで、本発明鋼Ａ１〜Ａ８は、Ｎｉ当量とＣの相対量が本発明で規定する範囲、すなわち、図１に示す点Ａ〜Ｅで囲まれる範囲にあり、一方、比較鋼Ｊ１〜Ｊ８は同図に示す点Ａ〜Ｅで囲まれる範囲外にある。Ｊ１、Ｊ２、Ｊ３は、Ｎｉ当量が本発明の範囲内にあるが、Ｃの含有量が点Ｃ、Ｄ、Ｅで結ばれる範囲よりも多いことから、成形性は有するが、反面、耐時期割れ性に劣る。また、Ｊ５、Ｊ６もＮｉ当量が本発明の範囲内にあるものの、Ｃの含有量が点Ａ、Ｂで結ばれる範囲よりも少ないことから、耐時期割れ性は有する反面、成形性に劣る。また、Ｎｉ当量が本発明の範囲外にあるＪ４、Ｊ８は、成形性、耐時期割れ性のいずれにも劣る。Ｊ７はＮｉ当量の上限と点Ａ、Ｂで結ばれるＣの下限に近いところで本発明から外れており、そのため、表２に示すように、耐時期割れ性は有しているが、成形性に劣る。
【００３０】
また、図２は、本発明の規定条件の一つである０．０３０ｗｔ％≦Ｃ＋０．５５Ｎ≦０．０８０ｗｔ％と、１．５≦Ｃ／Ｎ≦３．０の範囲を示している。本発明鋼Ａ１〜Ａ８は、これら範囲をともに満足する範囲に属しており、一方、比較鋼Ｂ、Ｃ、Ｄ、Ｅ、Ｆ、Ｇは、双方の条件が重なる範囲外にある。図２で明らかなように、「Ｃ＋０．５５Ｎ」が０．０８０ｗｔ％を超える（比較鋼Ｂ、Ｃ、Ｄ）と、成形性は有するものの耐時期割れ性に劣っている。また、「Ｃ＋０．５５Ｎ」が０．０３０ｗｔ％未満（比較鋼Ｇ）の場合には、成形性が確保されない。また、Ｃ／Ｎが１．５未満（比較鋼Ｅ）あるいは３．０を超える（比較鋼Ｆ）と、いずれも成形性がやや劣ってしまう。
【００３１】
また、表２からは、特にＣｕの含有量が低い比較鋼Ｈ１〜Ｈ３が耐時期割れ性に劣ることが判る。一方、本発明鋼のＡ９は、本発明鋼の中でもＣｕの含有量は比較的低いものの、成形性および耐時期割れ性は確保されている。
【００３２】
Ｂ．第２実施例
表３に示す成分組成（Ｂ１〜Ｂ３、いずれも本発明鋼）を有するオーステナイト系ステンレス鋼を、連続鋳造によって１５０ｍｍ厚のスラブに製造した後、これを１２５０℃に加熱し、次いで熱間圧延によって厚さ３ｍｍ、幅１０５０ｍｍの熱延鋼帯としたときの耳割れ（板の側縁部の割れ）について観察した。その結果を、表３に併記する。
【００３３】
【表３】

【００３４】
表３によれば、鋼Ｂ１〜Ｂ３は、いずれも本発明鋼であるが、Ｂ１、Ｂ２はいずれもＢを含有する点でＢ３と異なっている。Ｂを含有するＢ１、Ｂ２には耳割れの発生は認められず、一方、Ｂを含有しないＢ３には耳割れの発生が認められた。したがって、Ｂの含有により加工上の特性が向上し、ひいては歩留まりが向上して経済的にも有利になることが確かめられた。
【００３５】
【発明の効果】
以上説明したように、本発明によれば、Ｎｉ当量を独自に規定していることによりオーステナイトおよび加工誘起マルテンサイトの生成量を適度にバランスさせることができ、これによって、優れた張出し性、深絞り性、バーリング加工性および耐時期割れ性を兼備するプレス成形用オーステナイト系ステンレス鋼を提供することができる。
【図面の簡単な説明】
【図１】 Ｎｉ当量とＣの相対量の範囲を示す線図である。
【図２】 ０．０３０ｗｔ％≦Ｃ＋０．５５Ｎ≦０．０５０ｗｔ％の範囲および１．５≦Ｃ／Ｎ≦３．０の範囲を示す線図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an austenitic stainless steel, and more particularly to an austenitic stainless steel for press forming that has both stretchability, deep drawability, and burring workability, and has sufficient time cracking resistance.
[0002]
[Prior art]
Conventionally, SUS301, SUS304, etc. which are general-purpose stainless steels are mentioned as an austenitic stainless steel used for severe overhang forming. In these stainless steels, work-induced martensite is generated by cold working and exhibits remarkable work hardening. For this reason, although it is excellent in the overhang property in press work, there was a defect that cracks called time cracks occur in a product left after deep drawing. On the other hand, the burring process (hole expanding process) is a kind of stretch flange molding in which a hole is formed by punching a base plate, a punch is pressed around the hole, and stretch deformation is performed in the circumferential direction of the hole. As an austenitic stainless steel suitable for this processing method, SUS305 or the like, which is less prone to work-induced martensite than SUS304 and has high austenite phase stability, is used. However, such SUS305 and the like have a problem that deep drawability and stretchability are inferior to those of SUS301 and SUS304 because processing-induced martensite hardly occurs.
[0003]
[Problems to be solved by the invention]
In recent years, there has been a strong demand for the development of austenitic stainless steel that can be pressed into a complicated shape and has excellent time cracking resistance from the viewpoints of economy and design. The present invention has been made in view of such circumstances, and provides an unprecedented austenitic stainless steel for press forming that has excellent stretchability, deep drawability, burring workability, and time cracking resistance. The purpose is that.
[0004]
[Means for Solving the Problems]
The present inventors verified the component composition of the austenitic stainless steel while verifying the production status of austenite and work-induced martensite and the stretchability, deep drawability, burring workability, and time cracking resistance affected by the situation. Detailed examination was conducted. As a result, it is an index indicating the difficulty of processing-induced martensite transformation, and the Ni equivalent that influences the stability of the austenite phase (the austenite phase becomes stable when the Ni equivalent is high) is defined within a certain range. Thus, it has been found that the above physical properties are sufficiently combined. Specifically, when the Ni equivalent (wt%) represented by 24.2C + 13.7N + 0.35Si + 0.5Mn + Ni + 0.65Cr + 0.98Mo + 0.6Cu is in the range of 21.0 to 23.0 wt%, austenite and It was found that the amount of work-induced martensite produced was moderately balanced, and as a result, excellent stretchability, deep drawability, burring workability and time crack resistance were exhibited.
In addition, the present inventors have further obtained the following knowledge regarding C and N, which are austenite-forming elements and strengthen the austenite phase and the work-induced martensite phase.
First, the total amount weighted so that each element is almost equivalent from the degree of strengthening of the austenite phase and the work-induced martensite phase is “C + 0.55N”, and this total amount is in the range of 0.030 to 0.080 wt%. In particular, excellent time cracking resistance was exhibited. “C + 0.55N” greatly affects the susceptibility to time cracking, and when it exceeds 0.080 wt%, the sensitivity is remarkably increased, and when it is less than 0.030 wt%, sufficient overhangability, deep drawability and burring workability are obtained. I can't. In particular, in the present invention containing Cu, it is necessary that “C + 0.55N” is 0.030 wt% or more in order to sufficiently bring out the effect of Cu contributing to the stretchability, deep drawability and burring workability. .
In addition, the inventors of the present invention have a ratio of C to N (C / N) that is particularly a factor involved in the stretchability and burring workability, and when the C / N is 1.5 to 3.0. It has been found that both overhangability and burring workability are ensured.
[0005]
The austenitic stainless steel for press forming according to the present invention was made based on the above knowledge, and is extremely suitable as a material for overhang processing, a material for deep drawing or a material for burring, and in addition to time cracking resistance. The material is characterized by 0.030 wt% ≦ C ≦ 0.080 wt%, Si: 1.0 wt% or less, Mn: 3.0 wt% or less, S: 0.003 wt% Hereinafter, 6.0 wt% ≦ Ni ≦ 9.0 wt%, 15.0 wt% ≦ Cr ≦ 19.0 wt%, Mo: 1.0 wt% or less, 1.95 wt% ≦ Cu ≦ 4.0 wt%, N: 0 .050 wt% or less, and the balance consists of Fe and inevitable impurities, and
21.0 wt% ≦ Ni equivalent of the following formula (1) ≦ 23.0 wt%
Satisfied ,
0.030 wt% ≦ C + 0.55 N ≦ 0.080 wt%, and
1.5 ≦ C / N ≦ 3.0
Is satisfied .
Ni equivalent (wt%) = 24.2C + 13.7N + 0.35Si + 0.5Mn + Ni + 0.65Cr + 0.98Mo + 0.6Cu (1)
(In the above formula, each component element represents wt%)
[0006]
Hereinafter, the grounds for the above numerical limitation will be described together with the operation of the present invention.
C: 0.030 wt% ≦ C ≦ 0.080 wt%
C is a strong austenite-forming element and at the same time is very effective in strengthening the austenite phase and the work-induced martensite phase, and is an essential element for improving the stretchability and deep drawability. In particular, in an austenitic stainless steel containing Cu, it is an important element for drawing out the effect of improving the deep drawability of Cu, and it is necessary to be at least 0.030 wt%, preferably 0.040 wt% or more. However, if it exceeds 0.080 wt%, both the time cracking susceptibility and the intergranular corrosion sensitivity increase, so the upper limit was made 0.080 wt%.
[0007]
Si: 1.0 wt% or less Si is an effective deoxidizer and an indispensable element in the steelmaking process, and the higher the content thereof, the higher the work hardenability of the austenite phase, which is advantageous for the stretchability. . However, if it exceeds 1.0 wt%, a large amount of δ ferrite is generated at the time of solidification to inhibit hot workability, and the sensitivity to time cracking increases, so the upper limit of the content was set to 1.0 wt%.
[0008]
Mn: 3.0 wt% or less Mn acts as a deoxidizing agent and a desulfurizing agent, and further contributes to stabilization of the austenite phase, and preferably 0.1 wt% or more. However, if it exceeds 3.0 wt%, the austenite phase becomes too stable and the stretchability and deep drawability deteriorate, so it was set to 3.0 wt% or less.
[0009]
S: 0.003 wt% or less S is contained in a general-purpose austenitic stainless steel such as SUS304 in an amount of about 0.005 wt% as an unavoidable impurity. However, in steel containing Cu, hot workability is significantly inhibited. Since it is an element that deteriorates burring workability, the upper limit was made 0.003 wt%.
[0010]
Ni: 6.0 wt% ≦ Ni ≦ 9.0 wt%
If Ni is less than 6.0 wt%, a large amount of δ ferrite is generated during solidification, resulting in a decrease in hot workability, and if it exceeds 9.0 wt%, work-induced martensite is difficult to be generated, and the stretchability and depth are reduced. The drawability deteriorates. Therefore, the content of Ni is set to 6.0 to 9.0 wt%.
[0011]
Cr: 15.0 wt% ≦ Cr ≦ 19.0 wt%
When Cr is less than 15.0 wt%, the corrosion resistance becomes insufficient, and when it exceeds 19.0 wt%, δ ferrite is generated and hot workability is lowered, so that it is limited to the range of 15.0 to 19.0 wt%. did.
[0012]
Mo: 1.0 wt% or less Mo is generally known as an element that improves the corrosion resistance of stainless steel. However, since it is relatively expensive, 1.0 wt. % Was the upper limit.
[0013]
Cu: 1.0 wt% ≦ Cu ≦ 4.0 wt%
Cu is an element that remarkably improves the stretchability, deep drawability, burring workability and time cracking resistance of austenitic stainless steel, but its effect is poor at less than 1.0 wt%. Moreover, when it exceeds 4.0 wt%, hot workability will be inhibited remarkably. Therefore, the Cu content is 1.0 to 4.0 wt%, preferably 2.0 to 3.0 wt%.
[0014]
N: 0.050 wt% or less N is an austenite-forming element like C, and is an element that improves the strength of the austenite phase and the work-induced martensite phase. Unlike C, if N contains more than 0.050 wt%, deep drawability deteriorates, so it was made 0.050 wt% or less. Preferably it is 0.030 wt% or less.
[0015]
Ni equivalent: 21.0 wt% ≦ Ni equivalent of the following formula (1) ≦ 23.0 wt%
Ni equivalent (wt%) = 24.2C + 13.7N + 0.35Si + 0.5Mn + Ni + 0.65Cr + 0.98Mo + 0.6Cu (1)
(In the above formula, each component element represents wt%)
The Ni equivalent is an index indicating the difficulty of processing-induced martensite transformation. When the Ni equivalent is high, the austenite phase is stabilized. When the Ni equivalent is less than 21 wt%, the austenite phase becomes too unstable, and as a result, all of the stretchability, deep drawability and time crack resistance deteriorate. On the other hand, when the Ni equivalent exceeds 23.0 wt%, the austenite phase becomes too stable, and as a result, the amount of work-induced martensite is reduced and the burring workability and time cracking resistance are excellent, but the stretchability And deep drawability deteriorates extremely. Therefore, the Ni equivalent is preferably 21.0 to 23.0 wt%. In the present invention, the above Ni equivalent formula is obtained by using a ferrite scope to determine the relative amount of martensite in a test piece having an elongation of 30% in a tensile test, and arranging it as an index of the component.
[0016]
0.030 wt% ≦ C + 0.55N ≦ 0.080 wt% (each component element represents wt%)
As described above, in the range of “C + 0.55N” 0.030 to 0.080 wt%, particularly excellent time cracking resistance is exhibited, and when “C + 0.55N” exceeds 0.080 wt%, the sensitivity is remarkably high. In addition, if it is less than 0.030 wt%, sufficient stretchability, deep drawability and burring workability cannot be obtained. In this range, 0.050 to 0.080 wt% is more preferable.
[0018]
1.5 ≦ C / N ≦ 3.0
As described above, when C / N is 1.5 to 3.0, both stretchability and burring workability are ensured, so C / N satisfies 1.5 ≦ C / N ≦ 3.0. It is preferable to satisfy, and more preferably 1.75 ≦ C / N ≦ 2.5.
[0019]
As described above, the austenitic stainless steel for press molding of the present invention having the above component composition has excellent overhanging property, deep drawability and burring workability, so that it can be pressed into a complicated shape. Needless to say, it has excellent properties such as good time cracking resistance.
[0020]
Furthermore, the inventors of the present invention are the factors that improve the stretchability, deep drawability, burring workability, and time cracking resistance, because the relative amount of the Ni equivalent and the C content is the following (2) to ( It was found that the above physical properties were combined at a high level within the range satisfying all the conditional expressions 4).
In the range of 21.0 wt% ≦ Ni equivalent ≦ 23.0 wt%, 0.015 × (Ni equivalent−21) + 0.025 ≦ C (2)
In the range of 21.0 wt% ≦ Ni equivalent ≦ 22.0 wt%, 0.02 × (Ni equivalent−21) + 0.04 ≧ C (3)
In the range of 22.0 wt% <Ni equivalent ≦ 23.0 wt%, 0.005 × (Ni equivalent−22) + 0.06 ≧ C (4)
[0021]
The ranges of Ni equivalent and C defined by the above formulas (2) to (4) are point A (Ni equivalent: 21.0 wt%, C: 0.025 wt%) and B (Ni equivalent: 23) shown in FIG. 0.0 wt%, C: 0.055 wt%), C (Ni equivalent: 21.0 wt%, C: 0.04 wt%), D (Ni equivalent: 22.0 wt%, C: 0.06 wt%), E ( Ni equivalent: 23.0 wt%, C: 0.065 wt%). Therefore, in this invention, it is preferable that Ni equivalent and content of C exist in the range enclosed by the points A, B, C, D, and E shown in FIG.
[0022]
Furthermore, in this invention, in addition to the said element, B can be contained 0.0010 to 0.020 wt%. B is very effective in improving the hot workability of austenitic stainless steel containing Cu, but its effect is poor when it is less than 0.0010 wt%, and the susceptibility to solidification cracking is increased when it exceeds 0.020 wt%, and Corrosion resistance deteriorates. Therefore, when it contains B, 0.0010-0.020 wt% is preferable.
[0023]
【Example】
Next, examples will be presented to clarify the effects of the present invention.
A. First embodiment Component composition shown in Table 1 (A1 to A9 are component compositions of the present invention, J1 to J8, B, C, D, E, F, G, and H1 to 3 are components that are outside the present invention) Austenitic stainless steel having a composition) is melted into a steel ingot by 10 kg in an argon induction atmosphere induction furnace and hot rolled and cold rolled into a cold rolled sheet having a thickness of 0.8 mm. Finishing was then performed at 1100 ° C. for 30 minutes. The austenite grain size after annealing was 7-8. Each test material thus obtained was subjected to the following tests, and tests on the stretchability, deep drawability, burring workability and time cracking resistance were conducted.
[0024]
[Table 1]

[0025]
-Overhang property test-Erichsen value Eriksen value was determined by Eriksen test B method defined in "JIS Z 2247".
・ Deep drawability test-Limit drawing ratio (LDR)
A cylinder deep drawing test using a 40 mmφ flat head punch is conducted. If the limit drawing ratio (LDR) exceeds 2.20, the deep drawing property is excellent. ○, 2.10 to 2.20 is slightly inferior in deep drawing property As for △ and less than 2.10, it was evaluated as x because it was inferior in deep drawability.
[0026]
・ Burring workability test-Hole expansion rate First, a 10mmφ hole was made by punching the test material, and then this hole was expanded with a conical punch with an apex angle of 30 degrees. The diameter of the hole when penetrating was measured, and the hole expansion rate was determined by the following formula.
Hole expansion rate (%) = 100 × (D1-D0) / D0
(D0: initial hole diameter (= 10 mmφ), D1: hole diameter after test)
-Time crack resistance test 100 mmφ sample material was subjected to multistage drawing using a first drawing: 50 mmφ, second drawing: 45 mm, third drawing: 38 mmφ flat head punch and left at room temperature for 200 hours. The presence or absence of subsequent cracks was observed. The case where there was no occurrence of cracking was evaluated as ○, and the case where there was cracking was evaluated as ×.
The test results are shown in Table 2.
[0027]
[Table 2]

[0028]
As is clear from Table 2, the steels A1 to A9 of the present invention are all excellent in stretchability, deep drawability, burring workability (hereinafter collectively referred to as formability), and time cracking resistance. On the other hand, in each comparative steel, one of the component compositions defined in the present invention was outside the present invention, and one or more properties of formability and time cracking resistance were inferior.
[0029]
Here, the steels A1 to A8 of the present invention are in the range where the relative amounts of Ni equivalent and C are defined by the present invention, that is, the range surrounded by the points A to E shown in FIG. Is outside the range surrounded by points A to E shown in FIG. J1, J2, and J3 have Ni equivalents within the scope of the present invention, but the C content is higher than the range connected by points C, D, and E. Inferior to crackability. J5 and J6 also have Ni equivalents within the scope of the present invention, but the content of C is less than the range bound by points A and B, so they have time cracking resistance but are inferior in moldability. Moreover, J4 and J8 whose Ni equivalent is outside the scope of the present invention are inferior in both formability and time cracking resistance. J7 deviates from the present invention near the upper limit of Ni equivalent and the lower limit of C connected by points A and B. Therefore, as shown in Table 2, it has time cracking resistance, but in formability. Inferior.
[0030]
FIG. 2 shows the range of 0.030 wt% ≦ C + 0.55 N ≦ 0.080 wt% and 1.5 ≦ C / N ≦ 3.0, which is one of the defining conditions of the present invention. Invention steels A1 to A8 belong to a range that satisfies both of these ranges, while comparative steels B, C, D, E, F, and G are outside the range where both conditions overlap. As apparent from FIG. 2, when “C + 0.55N” exceeds 0.080 wt% (comparative steels B, C, D), although it has formability, it is inferior in time cracking resistance. Further, when “C + 0.55N” is less than 0.030 wt% (comparative steel G), formability is not ensured. Moreover, if C / N is less than 1.5 (Comparative Steel E) or exceeds 3.0 (Comparative Steel F), the formability is somewhat inferior.
[0031]
Further, from Table 2, it can be seen that comparative steels H1 to H3 having a particularly low Cu content are inferior in time cracking resistance. On the other hand, A9 of the steel according to the present invention has a relatively low Cu content among the steels according to the present invention, but the formability and the time crack resistance are ensured.
[0032]
B. Second example Austenitic stainless steel having the composition shown in Table 3 (B1 to B3, all of the present invention steel) was manufactured into a slab having a thickness of 150 mm by continuous casting. It was heated and then observed for ear cracks (cracks on the side edges of the plate) when hot rolled into a hot rolled steel strip having a thickness of 3 mm and a width of 1050 mm. The results are also shown in Table 3.
[0033]
[Table 3]

[0034]
According to Table 3, steels B1 to B3 are all steels of the present invention, but B1 and B2 are different from B3 in that both contain B. The occurrence of ear cracks was not observed in B1 and B2 containing B, whereas the occurrence of ear cracks was observed in B3 not containing B. Therefore, it has been confirmed that the inclusion of B improves the processing characteristics, which in turn improves the yield and is economically advantageous.
[0035]
【The invention's effect】
As described above, according to the present invention, the amount of austenite and work-induced martensite generated can be appropriately balanced by uniquely defining the Ni equivalent, thereby providing excellent extensibility, depth. An austenitic stainless steel for press forming that has both drawability, burring workability and time cracking resistance can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing a range of relative amounts of Ni equivalent and C.
FIG. 2 is a diagram showing a range of 0.030 wt% ≦ C + 0.55 N ≦ 0.050 wt% and a range of 1.5 ≦ C / N ≦ 3.0.

Claims (3)

0.030 wt% ≦ C ≦ 0.080 wt%, Si: 1.0 wt% or less, Mn: 3.0 wt% or less, S: 0.003 wt% or less, 6.0 wt% ≦ Ni ≦ 9.0 wt%, 15. 0 wt% ≦ Cr ≦ 19.0 wt%, Mo: 1.0 wt% or less, 1.95 wt% ≦ Cu ≦ 4.0 wt%, N: 0.050 wt% or less, with the balance from Fe and inevitable impurities And
21.0 wt% ≦ Ni equivalent of the following formula (1) ≦ 23.0 wt%
Satisfied ,
0.030 wt% ≦ C + 0.55 N ≦ 0.080 wt%, and
1.5 ≦ C / N ≦ 3.0
An austenitic stainless steel for press forming characterized by satisfying
Ni equivalent (wt%) = 24.2C + 13.7N + 0.35Si + 0.5Mn + Ni + 0.65Cr + 0.98Mo + 0.6Cu (1)
(In the above formula, each component element represents wt%) The Ni equivalent and C are points A (Ni equivalent: 21.0 wt%, C: 0.025 wt%) and B (Ni equivalent: 23.0 wt%, C: 0.055 wt%) shown in the attached drawings and FIG. ), C (Ni equivalent: 21.0 wt%, C: 0.04 wt%), D (Ni equivalent: 22.0 wt%, C: 0.06 wt%), E (Ni equivalent: 23.0 wt%, C: press-molding austenitic stainless steel according to satisfy the range surrounded in claim 1, wherein at 0.065wt%). 0.0010wt% ≦ B ≦ 0.020wt% is further characterized by containing claim 1 or 2 for press forming austenitic stainless steel according to.

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