JPH04214842A - High strength stainless steel excellent in workability - Google Patents

High strength stainless steel excellent in workability

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Publication number
JPH04214842A
JPH04214842A JP1502891A JP1502891A JPH04214842A JP H04214842 A JPH04214842 A JP H04214842A JP 1502891 A JP1502891 A JP 1502891A JP 1502891 A JP1502891 A JP 1502891A JP H04214842 A JPH04214842 A JP H04214842A
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Japan
Prior art keywords
less
sub
high strength
workability
value
Prior art date
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JP1502891A
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Japanese (ja)
Inventor
Yasushi Murata
康 村田
Yoshihiro Uematsu
美博 植松
Toshihiko Takemoto
敏彦 武本
Yoshiaki Hori
芳明 堀
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Nippon Steel Nisshin Co Ltd
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Nisshin Steel Co Ltd
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Priority to JP1502891A priority Critical patent/JPH04214842A/en
Publication of JPH04214842A publication Critical patent/JPH04214842A/en
Withdrawn legal-status Critical Current

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  • Heat Treatment Of Sheet Steel (AREA)
  • Heat Treatment Of Steel (AREA)

Abstract

PURPOSE:To obtain stainless steel excellent in workability as annealed, low in the degree of work hardening and provided with high strength by subzero treatment at about -73 deg.C. CONSTITUTION:This is stainless steel in which the content of each element is regulated so as to contain, by weight, 0.01 to 0.30% C, 0.2 to 3.0% Si, <=4.0% Mn, <=0.030% P, <=0.008% S, 3.0 to 7.0% Ni, 12.0 to 18.0% Cr, 0.01 to 0.25% N and 0.0003 to 0.30% B and so as to regulate A value defined by A value = Ni+0.61XMn+22.60XC+13.77XN+0.43XCr+0.33XSi+0.20XB to the range of 15.7 to 18.0 and the balance Fe with inevitable impurities.

Description

【発明の詳細な説明】 【0001】 【産業上の利用分野】本発明は,焼鈍状態で加工性に優
れ, 加工後のサブゼロ処理により高強度を発現する加
工性に優れた高強度ステンレス鋼に関するものである。 【0002】〔従来の技術と問題点〕 従来より,高強度ステンレス鋼として, 加工硬化型の
SUS301, SUS304或いは時効硬化型のSU
S630, SUS631などが多用され,各種ばね材
等に適用されている。SUS301に代表される加工硬
化型ステンレス鋼は冷間加工によるオーステナイト相の
加工硬化と高硬度の加工誘起マルテンサイトの生成によ
り高強度化させるものである。また,冷間加工後, 時
効処理によりさらに高強度化させる場合もある。しかし
ながら,これらの鋼は冷間加工を施して加工硬化させる
必要があり,その結果, 成形加工性に劣るという欠点
を有している。 【0003】一方, 時効硬化型ステンレス鋼は時効処
理により高強度は得られるものの,一般に加工性に乏し
く, また時効処理を400℃付近で行なう必要があり
,テンパーカラーが付く,時効処理時に変形する等の危
険性がある, といった問題がある。また,かような時
効処理ではなく−73℃程度の工業的に容易に得られる
温度でのサブゼロ処理により高強度化が図れるステンレ
ス鋼も知られているが,この系の材料は加工硬化が激し
いので,加工施工時に大きな負荷を必要とし作業性に劣
るという欠点を有している。さらに, この系の材料は
合金組成がわずかに変動すると,焼鈍状態でマルテンサ
イト相が多量に生成し,加工性が劣化するか,あるいは
サブゼロ処理を施しても材料が硬化しないという欠点を
有している。 【0004】〔発明の目的〕 したがって本発明の目的は,焼鈍状態で加工性に優れる
と同時に加工硬化の程度が低く,しかも−73℃程度の
サブゼロ処理により高強度が図れるステンレス鋼を提供
するにある。 【0005】〔発明の構成〕 前記の目的を達成せんとする本発明の要旨とするところ
は,重量%で,C:0.01〜0.30%, Si:0
.2〜3.0%, Mn:4.0 %以下, P:0.
030 %以下,S:0.008%以下,Ni:3.0
〜7.0%, Cr:12.0〜18.0%, N:0
.01〜0.25%, B:0.0003〜0.30%
を含有し,かつ  A値=Ni+0.61×Mn+22
.60×C+13.77×N+0.43×Cr+0.3
3×Si        +0.20×B で定義されるA値が15.7〜18.0の範囲となるよ
うに各元素の含有量が調整されるか, さらには,3.
0%以下のMo, 3.0%以下のCu, 3.0%以
下のCo, 0.5%以下のNb, 0.5%以下のV
, 0.5%以下のWまたは0.5%以下のTiの1種
または2種以上を含有したうえ,   A値=Ni+0
.61×Mn+22.60×C+13.77×N+0.
43×Cr+0.33×Si        +0.2
0×B+0.25×Mo+0.18×Cu+0.29×
Co+0.36×Nb        +0.33×V
+0.27×W+0.35×Tiで定義されるA値が1
5.7〜18.0の範囲となるように各元素の含有量が
調整され,残部がFeおよび不可避的不純物からなる,
 焼鈍状態で優れた加工性を有しサブゼロ処理によって
高強度を発現する加工性に優れた高強度ステンレス鋼に
ある。 【0006 】〔発明の詳述〕 一般にオーステナイト系ステンレス鋼においてはCr,
Niなどの主成分の含有量でMs点 (焼入れマルテン
サイト相が生成し始める温度) が大きく変動する。本
発明者等の研究によれば,焼鈍状態での主な組織がオー
ステナイト相で,且つそのMs点が室温付近となるよう
に成分設計を行えば良好な加工性を示すことになるが,
 これにSiを適量含有させると加工性が著しく向上す
ること,またBを適量含有させると加工硬化を増大する
ことなしに十分な焼入れ性を得ることができ,従って加
工施工時の負荷を低減し作業性を改善できることがわか
った。さらに成型あるいは曲げなどの加工後,−73℃
程度の温度域にてマルテンサイト変態を誘起させるが,
そのさいBは多量のマルテンサイト相を成分変動に対し
て安定に生成せしめること,さらにSiはマルテンサイ
ト相を強化し,高強度化に極めて有効であることが明ら
かとなった。すなわち, Ms点が室温付近になるよう
成分調整されたCr−Ni系準安定型ステンレス鋼にお
いて,SiとBを複合的に添加すると焼鈍状態で優れた
加工性を示し,かつサブゼロ処理により高強度化させる
ことができることを見出した。本発明はこのような知見
事実のもとになされたものである。 【0007】先ず,本発明鋼の各成分とその含有量の限
定理由について説明する。Cは強力なオーステナイト生
成元素で,該A値の調整に必須の元素である。さらにC
はサブゼロ処理後に生成されるマルテンサイト相の高強
度化にも必須の元素であり,0.01%以上含有させる
必要がある。しかし,多量に含有すると本発明鋼の特徴
である優れた加工性が得られなくなり, また耐食性も
劣化するのでその上限を0.30%とする。 【0008】Siは本発明鋼の特徴である焼鈍状態での
優れた加工性を付与するのに必須の元素である。またサ
ブゼロ処理後に生成されるマルテンサイト相の高強度化
にも著しく有効に寄与する元素である。これらの効果を
発揮するにはSiを0.2%以上含有させる必要がある
。しかしながら,Siはフエライト生成元素であり,多
量に含有すると焼鈍後に多量のδフエライト相が生成し
,サブゼロ処理を施しても高強度が得られなくなる。こ
の理由からSiの上限を3.0%とする。 【0009】MnはNiと同様にオーステナイト生成元
素であり, A値を調整するのに必須の元素である。し
かしMnを多量に含有すると,溶製時にMnヒュームが
多量に発生しまた炉壁の損傷が激しくなるなどの理由に
よって製造が困難になるので,その上限を4.0%とす
る。 【0010】Pは多量に含有すると加工性が劣化するの
でその上限を0.030%とする。 【0011】Sはその大部分が介在物として存在し,加
工性を劣化させるため,その上限を0.008%とする
。  【0012】NiはMnと同様にオーステナイト
生成元素であり, A値を本発明で規定する範囲に調整
し,焼鈍状態でオーステナイト相を得るのに必要な元素
であり,このためには3.0%以上は必要である。しか
し,Niを多量に含有するとA値が増加しすぎ,サブゼ
ロ処理を施してもマルテンサイト相があまり生成されず
高強度が得られないのでその上限を7.0%とする。 【0013】Crはステンレス鋼の必須元素であり,良
好な耐食性を得るには12.0%以上の含有が必要であ
る。 また,A値を本発明で規定する範囲に調整するのに必須
の元素でもある。しかしCrは強力なフエライト生成元
素であり,あまり多量に含有すると焼鈍状態でδフエラ
イト相が生成し,サブゼロ処理後の高強度化が図れなく
なる。したがってその上限を18.0%とする。 【0014】Nは,Cと同様に強力なオーステナイト生
成元素であり,A値の調整に必須の元素である。またN
はCと同様にサブゼロ処理後に生成されるマルテンサイ
ト相の固溶強化元素であり,サブゼロ処理により高強度
を得るのに極めて有効な元素でもある。このためには0
.01%以上の含有が必要であるが,あまり多量に含有
すると鋼塊にブローホールが生じ, 健全な鋼塊が得ら
れなくなるため,その上限を0.25%とする。 【0015】Bは,焼鈍状態での加工硬化を増大するこ
となしに加工性を向上させるという作用を供する点で本
発明鋼の特徴的な元素である。しかも,Bはサブゼロ処
理により多量のマルテンサイト相を生成させるのに有効
に寄与する。さらに, Bは合金組成のばらつきに対し
て, 多量のマルテンサイト相を安定して生成させるの
に有効な元素である。これらの効果を発現させるために
はBを0.0003%以上含有させる必要がある。しか
しながら, 多量に含有すると多量のボライドが生成し
,熱間加工性が低下するためその上限を0.30%とす
る。 【0016】Moは耐食性の向上に寄与する元素である
。またサブゼロ処理後の高強度化にも寄与する有効な元
素である。しかしながら,MoはCrと同様にフエライ
ト生成元素であり,多量に含有するとδフエライト相が
生成され,サブゼロ処理を施しても高強度が得られなく
なる。したがって,その上限を3.0%とする。 【0017】Cuは焼鈍状態での加工性を向上するに有
効な元素である。しかし,あまり多量に含有すると製造
性が劣化するのでその上限を3.0%とする。 【0018】Coは耐食性の向上に寄与する元素である
。また,Coはオーステナイト生成元素でA値を調整し
,焼鈍状態でオーステナイト相を得るのに有効な元素で
あるとともに,サブゼロ処理後の生成マルテンサイト量
を増大させ,高強度化に寄与する元素でもある。しかし
多量に含有させるとA値が増大し,サブゼロ処理を施し
てもマルテンサイト相が生成しないこともあり高強度が
得られなくなるので,その上限を3.0%とする。 【0019】Nb,V,WおよびTiは耐粒界腐食性を
向上するに有効な元素である。しかし,いずれも添加量
が増えるとδフエライトが生成され熱間加工性が劣化す
るためそれぞれの上限を0.5%とする。 【0020】A値は,本鋼の特徴である焼鈍状態で優れ
た加工性を有し,且つサブゼロ処理により高強度を得る
ための指標として,本発明鋼の開発中に実験室的に得ら
れたもので次式にて定義され,各成分の含有量が前述の
範囲であっても,このA値が15.7〜18.0の範囲
となるように各成分量が調整されることが本発明の目的
達成には必要である。   A値=Ni+0.61×Mn+22.60×C+1
3.77×N+0.43×Cr+0.33×Si   
     +0.20×B+0.25×Mo+0.18
×Cu+0.29×Co+0.36×Nb      
  +0.33×V+0.27×W+0.35×Ti【
0021】図1は,各成分量を前述の各々の範囲内で変
化させてA値を変えた鋼を同一条件で焼鈍した焼鈍材お
よび同一条件でサブゼロ処理したサブゼロ処理材のマル
テンサイト量を測定し,A値との関係を見たものである
。同図に見られるように,A値が15.7未満であると
,焼鈍状態でマルテンサイト相が多量に生成されるので
既に高強度となり加工性に乏しい。また, サブゼロ処
理を施した場合もマルテンサイト量の増加傾向は頭打ち
となり強度の上昇割合も小さい。他方, A値が18.
0を超えた場合には,焼鈍状態ではオーステナイト単相
となり加工性は優れるものの,オーステナイト相が安定
になりすぎ,サブゼロ処理を施してもマルテンサイト相
があまり生成されず高強度が得られない。これに対し,
A値の範囲は15.7〜18.0では焼鈍状態でマルテ
ンサイトは殆んど生じないか生じても極めて少なく,従
って加工性が良好でありサブゼロ処理を施すと充分なマ
ルテンサイトが生成して高強度となる。したがってA値
の範囲が15.7〜18.0の範囲となるように前記の
各成分量の範囲で各成分量を調整することが本発明の目
的達成には必要となる。 なお,図1の破線は,Bを添加しないで前記と同様にA
値を変化させた対照鋼の焼鈍材およびサブゼロ処理材に
ついてマルテンサイト量とA値の関係を示したものであ
る。実線の前記B添加鋼と比較すると,焼鈍材では本発
明に従うB添加鋼と対照のB無添加鋼とではマルテンサ
イト量に大きな差はないが,サブゼロ処理材では,Bを
添加した本発明鋼の方がマルテンサイト量が多くなって
おり,B添加の効果が認められる。以下に実施例を挙げ
て本発明の効果を具体的に示す。 【0022】 【実施例】表1に供試鋼の化学成分並びにA値を示した
。A1〜A3鋼は従来鋼である。B1〜B20鋼は本発
明鋼である。また,C1〜C3鋼は比較鋼であり本発明
で規定する範囲を外れた成分含有量の鋼である。これら
の鋼を真空溶解法にて12kg溶製して鋳造し,得られ
た鋼塊を鍛造後, 熱間圧延により3mm厚みの板とし
,溶体化処理後,冷間圧延と焼鈍を繰り返し,1.0m
m厚みの焼鈍板を得た。これを供試材として,ドライア
イスで冷却したメチルアルコール (−73℃)内に1
時間保持するサブゼロ処理を施した。表2に,各鋼の焼
鈍材並びにサブゼロ処理材のマルテンサイト量(M量)
と,硬さおよび引張特性を示した。 【0023】 【表1】 【0024】 【表2】 【0025】表2の結果に見られるように,従来鋼のA
1,A2,A3鋼ではA値がいずれも18.0を越えて
おり,焼鈍材, サブゼロ処理材ともにマルテンサイト
量は0.5%以下であってオーステナイト相は安定であ
る。したがって,硬さおよび引張特性はサブゼロ処理を
施してもほとんど変化しない。 【0026】比較鋼のC1鋼では各元素の含有量は本発
明の範囲であるが,A値が14.65と低いため焼鈍材
ですでにマルテンサイト相が多量に存在し,硬さが51
4と高く, 伸びが4.1%と低くて加工性が乏しい。 C2鋼では各元素の含有量は本発明の範囲であるが,A
値が19.38と高いので焼鈍材でマルテンサイト相が
存在せず,硬さが238,伸びが37.8%と良好な加
工性を有しているが,サブゼロ処理材の生成マルテンサ
イト量が少なく, 硬さ, 引張強さはほとんど変化し
ない。また,C3鋼はA値が17.54で本発明の範囲
であるが,C量が低いのでサブゼロ処理後の硬さが27
8と低く高強度とは言えない。 【0027】これに対して, 本発明鋼はすべてA値が
15.7〜18.0の範囲であり,焼鈍材での硬さが3
00以下と低く, かつ伸びも30%以上あり,優れた
加工性を有している。そして, サブゼロ処理後では硬
さが400以上まで増加し高強度化していることがわか
る。 【0028】以上のように本発明鋼はMs点を室温付近
になるように成分調整した鋼にSiとBを複合添加する
ことにより溶体化処理状態で優れた加工性を有し, か
つ−73℃程度の温度域でのサブゼロ処理を施すことに
よって高強度が得られるものであり,サブゼロ処理後に
脱スケールなどの後処理の必要もない。したがってその
工業的価値が極めて高い高強度ステンレス鋼材料を提供
するものである。
Detailed Description of the Invention [0001] [Industrial Application Field] The present invention relates to a high-strength stainless steel that has excellent workability in an annealed state and develops high strength through sub-zero treatment after working. It is something. [Prior art and problems] Conventionally, work-hardening type SUS301, SUS304 or age-hardening type SU have been used as high-strength stainless steels.
S630, SUS631, etc. are frequently used and are applied to various spring materials. Work-hardening stainless steel, typified by SUS301, has high strength through work-hardening of the austenite phase through cold working and the formation of highly hard work-induced martensite. Additionally, after cold working, aging treatment may be used to further increase the strength. However, these steels need to be work-hardened by cold working, and as a result, they have the disadvantage of poor formability. On the other hand, although age-hardening stainless steel can obtain high strength through aging treatment, it generally has poor workability and requires aging treatment at around 400°C, which results in temper coloring and deformation during aging treatment. There are problems such as the risk of Additionally, there are stainless steels that can be made stronger by undergoing sub-zero treatment at an industrially easily obtained temperature of around -73°C instead of such aging treatment, but this type of material is subject to severe work hardening. Therefore, it has the disadvantage that it requires a large load during processing and is inferior in workability. Furthermore, this type of material has the disadvantage that if the alloy composition changes slightly, a large amount of martensite phase will be generated in the annealed state, resulting in poor workability, or the material will not harden even after sub-zero treatment. ing. [Object of the Invention] Therefore, the object of the present invention is to provide a stainless steel that has excellent workability in an annealed state, has a low degree of work hardening, and can achieve high strength through sub-zero treatment at about -73°C. be. [Structure of the Invention] The gist of the present invention, which aims to achieve the above-mentioned object, is that, in weight %, C: 0.01 to 0.30%, Si: 0
.. 2 to 3.0%, Mn: 4.0% or less, P: 0.
030% or less, S: 0.008% or less, Ni: 3.0
~7.0%, Cr:12.0~18.0%, N:0
.. 01~0.25%, B:0.0003~0.30%
and A value=Ni+0.61×Mn+22
.. 60×C+13.77×N+0.43×Cr+0.3
Whether the content of each element is adjusted so that the A value defined by 3 x Si + 0.20 x B is in the range of 15.7 to 18.0, and 3.
0% or less Mo, 3.0% or less Cu, 3.0% or less Co, 0.5% or less Nb, 0.5% or less V
, contains one or more of 0.5% or less W or 0.5% or less Ti, and has an A value = Ni + 0
.. 61×Mn+22.60×C+13.77×N+0.
43×Cr+0.33×Si+0.2
0×B+0.25×Mo+0.18×Cu+0.29×
Co+0.36×Nb+0.33×V
A value defined by +0.27×W+0.35×Ti is 1
The content of each element is adjusted to be in the range of 5.7 to 18.0, with the remainder consisting of Fe and inevitable impurities.
It is a high-strength stainless steel with excellent workability that has excellent workability in the annealed state and develops high strength through sub-zero treatment. [Detailed Description of the Invention] Generally, austenitic stainless steel contains Cr,
The Ms point (temperature at which the quenched martensitic phase begins to form) varies greatly depending on the content of main components such as Ni. According to the research conducted by the present inventors, if the composition is designed so that the main structure in the annealed state is an austenite phase and the Ms point is near room temperature, good workability will be exhibited.
When an appropriate amount of Si is added to this, the workability is significantly improved, and when an appropriate amount of B is added, sufficient hardenability can be obtained without increasing work hardening, thus reducing the load during processing. It was found that workability could be improved. After further processing such as molding or bending, -73℃
Although martensitic transformation is induced in a temperature range of
At this time, it was revealed that B allows a large amount of martensitic phase to be generated stably against fluctuations in composition, and that Si strengthens the martensitic phase and is extremely effective in increasing strength. In other words, in a Cr-Ni metastable stainless steel whose composition has been adjusted so that the Ms point is near room temperature, the combined addition of Si and B shows excellent workability in the annealed state, and the sub-zero treatment provides high strength. We discovered that it is possible to transform The present invention has been made based on these findings. First, the various components of the steel of the present invention and the reason for limiting their content will be explained. C is a strong austenite-forming element and is an essential element for adjusting the A value. Further C
is an essential element for increasing the strength of the martensitic phase produced after sub-zero treatment, and must be contained in an amount of 0.01% or more. However, if it is contained in a large amount, the excellent workability that characterizes the steel of the present invention cannot be obtained, and the corrosion resistance also deteriorates, so the upper limit is set at 0.30%. [0008]Si is an essential element for imparting excellent workability in the annealed state, which is a characteristic of the steel of the present invention. It is also an element that significantly and effectively contributes to increasing the strength of the martensitic phase produced after sub-zero treatment. In order to exhibit these effects, it is necessary to contain 0.2% or more of Si. However, Si is a ferrite-forming element, and if it is contained in a large amount, a large amount of δ-ferrite phase will be generated after annealing, making it impossible to obtain high strength even if sub-zero treatment is performed. For this reason, the upper limit of Si is set to 3.0%. [0009] Like Ni, Mn is an austenite-forming element and is an essential element for adjusting the A value. However, if a large amount of Mn is contained, manufacturing becomes difficult because a large amount of Mn fume is generated during melting and the furnace wall is severely damaged, so the upper limit is set at 4.0%. [0010] When P is contained in a large amount, processability deteriorates, so the upper limit is set at 0.030%. [0011] Most of S exists as inclusions and deteriorates workability, so the upper limit of S is set at 0.008%. Ni, like Mn, is an austenite-forming element, and is an element necessary to adjust the A value within the range specified in the present invention and obtain an austenite phase in the annealed state. % or more is necessary. However, if a large amount of Ni is contained, the A value will increase too much, and even if sub-zero treatment is performed, the martensite phase will not be formed much and high strength will not be obtained, so the upper limit is set at 7.0%. [0013] Cr is an essential element for stainless steel, and must be contained in an amount of 12.0% or more in order to obtain good corrosion resistance. It is also an essential element for adjusting the A value within the range specified by the present invention. However, Cr is a strong ferrite-forming element, and if it is contained in too large a quantity, a δ-ferrite phase will be generated in the annealing state, making it impossible to achieve high strength after sub-zero treatment. Therefore, the upper limit is set to 18.0%. [0014] Like C, N is a strong austenite-forming element, and is an essential element for adjusting the A value. Also N
Like C, C is a solid solution strengthening element for the martensitic phase produced after sub-zero treatment, and is also an extremely effective element in obtaining high strength through sub-zero treatment. For this purpose 0
.. It is necessary for the content to be 0.1% or more, but if the content is too large, blowholes will occur in the steel ingot, making it impossible to obtain a sound steel ingot, so the upper limit is set at 0.25%. B is a characteristic element of the steel of the present invention in that it provides the effect of improving workability without increasing work hardening in the annealed state. Moreover, B effectively contributes to generating a large amount of martensite phase by subzero treatment. Furthermore, B is an effective element for stably generating a large amount of martensitic phase despite variations in alloy composition. In order to exhibit these effects, it is necessary to contain B at 0.0003% or more. However, if it is contained in a large amount, a large amount of boride will be generated and hot workability will deteriorate, so the upper limit is set at 0.30%. Mo is an element that contributes to improving corrosion resistance. It is also an effective element that contributes to high strength after sub-zero treatment. However, like Cr, Mo is a ferrite-forming element, and if it is contained in a large amount, a δ-ferrite phase will be generated, making it impossible to obtain high strength even if sub-zero treatment is performed. Therefore, the upper limit is set at 3.0%. [0017] Cu is an effective element for improving workability in an annealed state. However, if too large a content is contained, the manufacturability will deteriorate, so the upper limit is set at 3.0%. [0018] Co is an element that contributes to improving corrosion resistance. In addition, Co is an austenite-forming element that is effective in adjusting the A value and obtaining an austenite phase in the annealed state, and is also an element that increases the amount of martensite formed after sub-zero treatment and contributes to high strength. be. However, if it is contained in a large amount, the A value will increase, and even if sub-zero treatment is performed, martensitic phase may not be generated, making it impossible to obtain high strength, so the upper limit is set at 3.0%. Nb, V, W and Ti are effective elements for improving intergranular corrosion resistance. However, if the amount added increases in either case, δ ferrite is generated and hot workability deteriorates, so the upper limit for each is set at 0.5%. [0020] The A value was obtained in a laboratory during the development of the steel of the present invention as an index for achieving excellent workability in the annealed state, which is a characteristic of the steel, and obtaining high strength through sub-zero treatment. It is defined by the following formula, and even if the content of each component is within the above range, the amount of each component can be adjusted so that the A value is in the range of 15.7 to 18.0. This is necessary to achieve the objectives of the present invention. A value=Ni+0.61×Mn+22.60×C+1
3.77×N+0.43×Cr+0.33×Si
+0.20×B+0.25×Mo+0.18
×Cu+0.29×Co+0.36×Nb
+0.33×V+0.27×W+0.35×Ti [
[0021] Figure 1 shows the measurement of the amount of martensite in annealed steel with different A values by varying the amount of each component within the above-mentioned ranges and in annealed steel under the same conditions and sub-zero treated steel under the same conditions. However, we looked at the relationship with the A value. As seen in the figure, when the A value is less than 15.7, a large amount of martensite phase is generated in the annealing state, resulting in already high strength and poor workability. Furthermore, even when sub-zero treatment is applied, the increase in the amount of martensite reaches a plateau, and the rate of increase in strength is also small. On the other hand, the A value is 18.
If it exceeds 0, the austenite phase becomes a single phase in the annealed state and the workability is excellent, but the austenite phase becomes too stable and even if sub-zero treatment is performed, the martensite phase is not generated much and high strength cannot be obtained. On the other hand,
When the A value is in the range of 15.7 to 18.0, almost no martensite is produced in the annealed state, or even if it is produced, it is extremely small, so workability is good, and sufficient martensite is produced when sub-zero treatment is performed. This results in high strength. Therefore, in order to achieve the object of the present invention, it is necessary to adjust the amount of each component within the above-mentioned range so that the A value is in the range of 15.7 to 18.0. Note that the broken line in Figure 1 indicates the same as above without adding B.
The relationship between the amount of martensite and the A value is shown for annealed control steels and sub-zero treated steels whose values have been changed. When compared with the B-added steel indicated by the solid line, there is no significant difference in the amount of martensite between the B-added steel according to the present invention and the control B-free steel in the annealed material, but in the sub-zero treated material, the B-added steel of the present invention The amount of martensite is larger in the case of , and the effect of B addition is recognized. EXAMPLES The effects of the present invention will be specifically illustrated by examples below. [Example] Table 1 shows the chemical composition and A value of the test steel. A1 to A3 steels are conventional steels. B1 to B20 steels are steels of the present invention. Further, C1 to C3 steels are comparative steels and have component contents outside the range specified by the present invention. 12 kg of these steels were melted and cast using the vacuum melting method, and the resulting steel ingot was forged and then hot rolled into a 3 mm thick plate. After solution treatment, cold rolling and annealing were repeated for 1 hour. .0m
An annealed plate having a thickness of m was obtained. This was used as a test material and placed in methyl alcohol (-73℃) cooled with dry ice.
Sub-zero processing to maintain time was applied. Table 2 shows the amount of martensite (M amount) in the annealed material and sub-zero treated material of each steel.
, hardness and tensile properties. [Table 1] [Table 2] [Table 2] As seen from the results in Table 2, conventional steel A
1, A2, and A3 steels all have A values exceeding 18.0, and both the annealed material and the sub-zero treated material have a martensite content of 0.5% or less, and the austenite phase is stable. Therefore, the hardness and tensile properties hardly change even after subzero treatment. In C1 steel, which is a comparison steel, the content of each element is within the range of the present invention, but since the A value is as low as 14.65, a large amount of martensitic phase already exists in the annealed material, and the hardness is 51.
4, elongation is low at 4.1%, and workability is poor. In C2 steel, the content of each element is within the range of the present invention, but A
Since the value is high at 19.38, there is no martensite phase in the annealed material, and it has good workability with a hardness of 238 and an elongation of 37.8%. However, the amount of martensite produced in the sub-zero treated material is There is little change in hardness and tensile strength. In addition, C3 steel has an A value of 17.54, which is within the range of the present invention, but because the C content is low, the hardness after sub-zero treatment is 27.
It is low at 8 and cannot be called high strength. On the other hand, all of the steels of the present invention have A values in the range of 15.7 to 18.0, and the hardness of annealed materials is 3.
It has a low elongation of less than 0.00 and has an elongation of more than 30%, and has excellent workability. It can be seen that after sub-zero treatment, the hardness increased to over 400 and the strength was increased. As described above, the steel of the present invention has excellent workability in the solution treatment state by adding Si and B in combination to the steel whose composition has been adjusted so that the Ms point is near room temperature, and -73 High strength can be obtained by performing sub-zero treatment in a temperature range of approximately ℃, and there is no need for post-treatment such as descaling after sub-zero treatment. Therefore, the present invention provides a high-strength stainless steel material that has extremely high industrial value.

【図面の簡単な説明】[Brief explanation of the drawing]

【図1】本発明に従うA値と焼鈍材およびサブゼロ処理
材のマルテンサイト量との関係を示す図である。
FIG. 1 is a diagram showing the relationship between the A value and the amount of martensite in an annealed material and a sub-zero treated material according to the present invention.

Claims (2)

【特許請求の範囲】[Claims] 【請求項1】  重量%で,C:0.01〜0.30%
, Si:0.2〜3.0%, Mn:4.0%以下,
 P:0.030%以下, S:0.008%以下,N
i:3.0〜7.0%, Cr:12.0〜18.0%
, N:0.01〜0.25%, B:0.0003〜
0.30%を含有し,かつ  A値=Ni+0.61×
Mn+22.60×C+13.77×N+0.43×C
r+0.33×Si        +0.20×B で定義されるA値が15.7〜18.0の範囲となるよ
うに各元素の含有量が調整され, 残部がFeおよび不
可避的不純物から成るステンレス鋼であって,焼鈍状態
で優れた加工性を有しサブゼロ処理によって高強度を発
現する加工性に優れた高強度ステンレス鋼。
[Claim 1] C: 0.01 to 0.30% by weight
, Si: 0.2 to 3.0%, Mn: 4.0% or less,
P: 0.030% or less, S: 0.008% or less, N
i: 3.0-7.0%, Cr: 12.0-18.0%
, N: 0.01~0.25%, B: 0.0003~
Contains 0.30% and A value=Ni+0.61×
Mn+22.60×C+13.77×N+0.43×C
Stainless steel in which the content of each element is adjusted so that the A value defined by r + 0.33 x Si + 0.20 x B is in the range of 15.7 to 18.0, with the remainder consisting of Fe and unavoidable impurities. A high-strength stainless steel with excellent workability that has excellent workability in the annealed state and develops high strength through sub-zero treatment.
【請求項2】  重量%で, C:0.01〜0.30
%, Si:0.2〜3.0%, Mn:4.0%以下
, P:0.030%以下, S:0.008%以下,
 Ni:3.0〜7.0%, Cr:12.0〜18.
0%, N:0.01〜0.25%, B:0.000
3〜0.30%を含有したうえ,さらに,Mo:3.0
%以下, Cu:3.0%以下, Co:3.0%以下
, Nb:0.5%以下, V:0.5%以下, W:
0.5%以下, Ti:0.5%以下の1種または2種
以上を含有し,かつ,  A値=Ni+0.61×Mn
+22.60×C+13.77×N+0.43×Cr+
0.33×Si        +0.20×B+0.
25×Mo+0.18×Cu+0.29×Co+0.3
6×Nb        +0.33×V+0.27×
W+0.35×Tiで定義されるA値が15.7〜18
.0の範囲となるように各元素の含有量が調整され,残
部がFeおよび不可避的不純物からなるステンレス鋼で
あって, 焼鈍状態で優れた加工性を有しサブゼロ処理
によって高強度を発現する加工性に優れた高強度ステン
レス鋼。
[Claim 2] C: 0.01 to 0.30 in weight%
%, Si: 0.2 to 3.0%, Mn: 4.0% or less, P: 0.030% or less, S: 0.008% or less,
Ni: 3.0-7.0%, Cr: 12.0-18.
0%, N: 0.01-0.25%, B: 0.000
In addition to containing 3 to 0.30%, Mo: 3.0
% or less, Cu: 3.0% or less, Co: 3.0% or less, Nb: 0.5% or less, V: 0.5% or less, W:
0.5% or less, contains one or more of Ti: 0.5% or less, and A value = Ni + 0.61 × Mn
+22.60×C+13.77×N+0.43×Cr+
0.33×Si +0.20×B+0.
25×Mo+0.18×Cu+0.29×Co+0.3
6×Nb +0.33×V+0.27×
A value defined by W + 0.35 x Ti is 15.7 to 18
.. This is a stainless steel in which the content of each element is adjusted to be in the 0 range, with the remainder consisting of Fe and unavoidable impurities, and has excellent workability in the annealed state and develops high strength through sub-zero treatment. High strength stainless steel with excellent durability.
JP1502891A 1990-01-19 1991-01-16 High strength stainless steel excellent in workability Withdrawn JPH04214842A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP1502891A JPH04214842A (en) 1990-01-19 1991-01-16 High strength stainless steel excellent in workability

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2-8205 1990-01-19
JP820590 1990-01-19
JP1502891A JPH04214842A (en) 1990-01-19 1991-01-16 High strength stainless steel excellent in workability

Publications (1)

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JPH04214842A true JPH04214842A (en) 1992-08-05

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Country Link
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006249559A (en) * 2005-03-14 2006-09-21 Nisshin Steel Co Ltd Surface supporting plate made from stainless steel
JP2016135921A (en) * 2009-11-02 2016-07-28 エイティーアイ・プロパティーズ・インコーポレーテッド Lean austenitic stainless steel
US9617628B2 (en) 2007-11-29 2017-04-11 Ati Properties Llc Lean austenitic stainless steel
US9624564B2 (en) 2007-12-20 2017-04-18 Ati Properties Llc Corrosion resistant lean austenitic stainless steel
US9873932B2 (en) 2007-12-20 2018-01-23 Ati Properties Llc Lean austenitic stainless steel containing stabilizing elements
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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006249559A (en) * 2005-03-14 2006-09-21 Nisshin Steel Co Ltd Surface supporting plate made from stainless steel
US9617628B2 (en) 2007-11-29 2017-04-11 Ati Properties Llc Lean austenitic stainless steel
US10370748B2 (en) 2007-11-29 2019-08-06 Ati Properties Llc Lean austenitic stainless steel
US9624564B2 (en) 2007-12-20 2017-04-18 Ati Properties Llc Corrosion resistant lean austenitic stainless steel
US9822435B2 (en) 2007-12-20 2017-11-21 Ati Properties Llc Lean austenitic stainless steel
US9873932B2 (en) 2007-12-20 2018-01-23 Ati Properties Llc Lean austenitic stainless steel containing stabilizing elements
US10323308B2 (en) 2007-12-20 2019-06-18 Ati Properties Llc Corrosion resistant lean austenitic stainless steel
JP2016135921A (en) * 2009-11-02 2016-07-28 エイティーアイ・プロパティーズ・インコーポレーテッド Lean austenitic stainless steel
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