JP2019127613A - High hardness precipitation hardening stainless steel having excellent hot workability and requiring no sub-zero treatment - Google Patents
High hardness precipitation hardening stainless steel having excellent hot workability and requiring no sub-zero treatment Download PDFInfo
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この出願は、プロペラシャフト、ドライブシャフト、軸受およびロールなどの高硬度、高耐食性が求められる部材として使用するためのステンレス鋼に関し、特に熱間加工性に優れ、サブゼロ処理を要しない高硬度析出硬化型ステンレス鋼に関する。 This application relates to stainless steel for use as a member requiring high hardness and high corrosion resistance such as propeller shafts, drive shafts, bearings and rolls, and in particular, high hardness precipitation hardening which is excellent in hot workability and does not require subzero treatment. Type stainless steel.
析出硬化型ステンレス鋼は、ステンレス鋼としての耐食性に加えて、析出硬化による強度を付与したものであり、基質組織によってマルテンサイト系、セミマルテンサイト系、オーステナイト系に分類される。オーステナイト系は非磁性用途に使用できる。マルテンサイト系、セミマルテンサイト系は、オーステナイトに固溶し、マルテンサイトにはほとんど溶解度をもたない金属または化合物をマルテンサイト変態後にマルテンサイト地より析出させるものである。マルテンサイト変態と析出硬化とを組み合わせて利用する点に特長がある。 Precipitation hardening type stainless steel is provided with strength by precipitation hardening in addition to corrosion resistance as stainless steel, and is classified into martensite, semimartensite, and austenite depending on the substrate structure. Austenitic can be used for non-magnetic applications. The martensite and semimartensite systems are those in which a metal or compound that dissolves in austenite and has almost no solubility in martensite is precipitated from the martensite base after martensite transformation. It is characterized in that martensite transformation and precipitation hardening are used in combination.
析出硬化型ステンレス鋼としては、Ｃ≦０．０５ｍａｓｓ％、０．５≦Ｓｉ＜２．０ｍａｓｓ％、Ｍｎ≦１．５０ｍａｓｓ％、２．０≦Ｃｕ≦５．０ｍａｓｓ％、２．０≦Ｎｉ＜７．０ｍａｓｓ％、１０．０≦Ｃｒ≦１５．０ｍａｓｓ％、１．０≦Ｃｏ≦５．０ｍａｓｓ％、２．０＜Ｍｏ≦５．０ｍａｓｓ％、０．５＜Ｔｉ≦３．０ｍａｓｓ％、及び、Ｎ≦０．０５ｍａｓｓ％を含み、残部がＦｅ及び不可避的不純物からなり、Ｓｉ＋Ｔｉ＋Ｃｏ≧４．５及びＳｉ／Ｍｏ≦０．７を満たす析出硬化型ステンレス鋼が提案されている（例えば、特許文献１参照。）。
この特許文献１は、所定の元素を含む鋼中に、Ｃｕを添加すると、固溶化熱処理および時効処理によりε−Ｃｕ相およびＧ相を析出させることにより硬度を増し、さらに質量比でＳｉ／Ｍｏ比を最適化することにより熱間加工性を向上させようとしている。もっとも、この特許は、鋼の成分としてＣｏが必須元素とされている。またＳｉ／Ｍｏ≦０．７を満足させることにより、熱間加工性を改善しようとしているが、さらに一層の熱間加工性の向上を図った析出硬化型ステンレス鋼の開発や、またＣｏやＭｏなどの高価な元素の使用をできるだけ減らすことが求められている。
As precipitation hardening type stainless steel, C ≦ 0.05 mass%, 0.5 ≦ Si <2.0 mass%, Mn ≦ 1.50 mass%, 2.0 ≦ Cu ≦ 5.0 mass%, 2.0 ≦ Ni < 7.0 mass%, 10.0 ≦ Cr ≦ 15.0 mass%, 1.0 ≦ Co ≦ 5.0 mass%, 2.0 <Mo ≦ 5.0 mass%, 0.5 <Ti ≦ 3.0 mass%, and And precipitation-hardenable stainless steels containing N ≦ 0.05 mass%, the balance being Fe and unavoidable impurities, and satisfying Si + Ti + Co ≧ 4.5 and Si / Mo ≦ 0.7 (eg, patent documents 1).
In Patent Document 1, when Cu is added to a steel containing a predetermined element, hardness is increased by depositing ε-Cu phase and G phase by solution heat treatment and aging treatment, and further, Si / Mo in mass ratio It is trying to improve the hot workability by optimizing the ratio. However, in this patent, Co is regarded as an essential element as a component of steel. In addition, we are trying to improve the hot workability by satisfying Si / Mo ≦ 0.7, but we have developed a precipitation-hardening stainless steel that further improves the hot workability, and also Co and Mo. It is required to reduce the use of expensive elements as much as possible.
一方、本願の出願人は、質量％で、Ｃ：０．０１〜０．１０％、Ｓｉ：０．３０〜２．００％、Ｍｎ：０．０１〜１．００％、Ｐ：０．０４０％以下、Ｓ：０．０３０％以下、Ｎｉ：４．０〜９．０％、Ｃｒ：１３．０〜２２．０％、Ｍｏ：０．２０〜２．００％、Ｃｕ：０．６０〜４．００％、Ｔｉ：０．５０〜３．５０％、Ｎｂ：０．０１〜２．００％、Ｎ：０．０５０％以下を含有し、残部Ｆｅおよび不可避不純物からなる、耐食性および製造性に優れた高硬度ステンレス鋼に関する特許出願をしている（特許文献２参照。）。この特許文献２には、高硬度および高耐食性を両立させ、かつ、高硬度が得られる熱処理範囲が広いことに着目した記載があり、耐食性を向上させるためにＣｒを１３．０％以上必要としている。しかしながら、この特許文献２では、残留オーステナイトをマルテンサイト変態させるために、−２０℃ないし−９０℃に１０分以上保持したサブゼロ処理を要しており、製造にコストが掛かるものであった。 On the other hand, the applicant of the present application is, by mass%, C: 0.01 to 0.10%, Si: 0.30 to 2.00%, Mn: 0.01 to 1.00%, P: 0.040 % Or less, S: 0.030% or less, Ni: 4.0 to 9.0%, Cr: 13.0 to 22.0%, Mo: 0.20 to 2.00%, Cu: 0.60 to Corrosion resistance and manufacturability containing 4.00%, Ti: 0.50 to 3.50%, Nb: 0.01 to 2.00%, N: 0.050% or less, the balance being Fe and unavoidable impurities Patent application for high-hardness stainless steel excellent in (see Patent Document 2). In this Patent Document 2, there is a description that pays attention to the fact that the heat treatment range in which high hardness and high corrosion resistance are compatible and high hardness can be obtained is wide, and Cr is required to be 13.0% or more in order to improve corrosion resistance. Yes. However, in this patent document 2, in order to transform the retained austenite into martensite, a sub-zero treatment that is held at −20 ° C. to −90 ° C. for 10 minutes or more is required, and manufacturing costs are high.
高硬度材が必要とされる用途では、マルテンサイト系ステンレス鋼であるＳＵＳ４２０などが用いられている。ところがマルテンサイト系ステンレス鋼はＣ含有量が相対的に多く、耐食性が低い。それに比べて、ＳＵＳ６３０などの析出硬化型ステンレス鋼は、耐食性に優れているものの、硬度が低いという問題がある。そこで、従来これを両立させるための調整が試みられてきたが十分ではなく、さらなる熱間加工性の向上や、またＣｏやＭｏなどの高価な元素をできるだけ減らすことが求められている。また、Ｍｓ点（マルテンサイト変態開始温度）が低いと残留オーステナイトが生成して硬さが低くなるため、それを回避するべくサブゼロ処理を用いることもある。しかし、サブゼロ処理ではドライアイスや液体窒素などの冷却剤を用いて冷却することから、非常にコストが掛かるという問題がある。 In applications where a high hardness material is required, SUS420, which is a martensitic stainless steel, is used. However, martensitic stainless steel has a relatively high C content and low corrosion resistance. In comparison, although precipitation hardened stainless steel such as SUS630 is excellent in corrosion resistance, it has a problem that hardness is low. Therefore, adjustments for achieving both of these have been attempted, but this is not sufficient, and further improvement of hot workability and reduction of expensive elements such as Co and Mo as much as possible are required. In addition, if the Ms point (martensitic transformation start temperature) is low, retained austenite is formed to lower the hardness, so sub-zero treatment may be used to avoid it. However, in the case of subzero treatment, cooling with a coolant such as dry ice or liquid nitrogen causes a problem of being very expensive.
そこで、本願が解決しようとする課題は、上記のようなサブゼロ処理を不要とし、かつ熱間加工性を向上させることで、製造性に優れた、高硬度析出硬化型のステンレス鋼を提供することである。 Therefore, the problem to be solved by the present application is to provide a high hardness precipitation hardening type stainless steel which is excellent in manufacturability by eliminating the above-described sub-zero treatment and improving hot workability. It is.
上記の課題を解決するための手段の、第１の手段では、質量％で、Ｃ：０．０１〜０．１０％、Ｓｉ：０．３０〜２．００％、Ｍｎ：０．０１〜１．００％、Ｎｉ：４．００〜９．００％、Ｃｒ：８．００〜１４．５０％、Ｍｏ：０．１０〜２．００％、Ｃｕ：０．５０〜４．００％、Ｔｉ：０．５０〜３．５０％を含有し、残部Ｆｅおよび不可避不純物からなり、下記の式（１）および式（２）を満足し、硬さが５５ＨＲＣ以上、残留オーステナイト量が１％以下、熱間引張試験（グリーブル試験）における絞り（ＲＡ）が６０％以上となる温度の範囲が１００℃以上であることを特徴とする製造性に優れた高硬度析出硬化型ステンレス鋼である。
５．００≦Ｎｉeq≦＜９．５０・・・式（１）
Ｎｉeq≦−０．８３×Ｃｒeq＋２５．５・・・式（２）
ただし、Ｎｉeq＝［％Ｎｉ］＋３０×（［％Ｃ］＋［％Ｎ］）＋０．５×［％Ｍｎ］＋０．３×［％Ｃｕ］であり、Ｃｒeq＝［％Ｃｒ］＋［％Ｍｏ］＋１．５×［％Ｓｉ］＋０．５×［％Ｎｂ］である。
なお、上記の［％Ｍ］には、いずれも対応する元素の含有量の数値（質量％）が代入される。
In the first means of the means for solving the above problems, C: 0.01 to 0.10%, Si: 0.30 to 2.00%, Mn: 0.01 to 1 by mass% 0.000%, Ni: 4.00 to 9.00%, Cr: 8.00 to 14.50%, Mo: 0.10 to 2.00%, Cu: 0.50 to 4.00%, Ti: Containing 0.50 to 3.50%, balance Fe and unavoidable impurities, satisfying Formula (1) and Formula (2) below, hardness 55 HRC or more, retained austenite content 1% or less, heat It is a high-hardness precipitation hardening stainless steel excellent in manufacturability, characterized in that the temperature range in which the drawing (RA) is 60% or more in the inter-tensile test (Gleeble test) is 100 ° C. or more.
5.00 ≦ Ni eq ≦ <9.50 Formula (1)
Ni eq ≦ −0.83 × Cr eq +25.5 formula (2)
However, Ni eq = [% Ni] + 30 × ([% C] + [% N]) + 0.5 × [% Mn] + 0.3 × [% Cu], and Cr eq = [% Cr] + [[ % Mo] + 1.5 × [% Si] + 0.5 × [% Nb].
The numerical value (mass%) of the content of the corresponding element is substituted for the above [% M].
第２の手段では、第１の手段の化学成分に加えて、質量％で、Ａｌ：０．００１〜０．１５０％、Ｎｂ：０．０１〜２．００％、Ｎ：０．００２〜０．０５０％、およびＳ：０．００１〜０．１００％から選択したいずれか１種または２種以上を含有し、ただし、第１の手段の化学成分の中のＣｒについては、Ｃｒ：８．００〜１３．００％未満とし、残部Ｆｅおよび不可避不純物からなり、下記の式（１）および式（２）を満足し、硬さが５５ＨＲＣ以上、残留オーステナイト量が１％以下、熱間引張試験（グリーブル試験）における絞り（ＲＡ）が６０％以上となる温度の範囲が１００℃以上であることを特徴とする製造性に優れた高硬度析出硬化型ステンレス鋼である。
５．００≦Ｎｉeq≦９．５０・・・式（１）
Ｎｉeq≦−０．８３×Ｃｒeq＋２５．５・・・式（２）
ただし、Ｎｉeq＝［％Ｎｉ］＋３０×（［％Ｃ］＋［％Ｎ］）＋０．５×［％Ｍｎ］＋０．３×［％Ｃｕ］であり、Ｃｒeq＝［％Ｃｒ］＋［％Ｍｏ］＋１．５×［％Ｓｉ］＋０．５×［％Ｎｂ］である。
なお、上記の［％Ｍ］には、いずれも対応する元素の含有量の数値（質量％）が代入される。
In the second means, in addition to the chemical components of the first means, in mass%, Al: 0.001 to 0.150%, Nb: 0.01 to 2.00%, N: 0.002 to 0 0.05% and S: 0.001 to 0.100%, or any one or two or more selected from the above, provided that Cr in the chemical component of the first means is Cr: 8. 00 to less than 13.00%, consisting of the balance Fe and unavoidable impurities, satisfying formula (1) and formula (2) below, hardness 55 HRC or more, retained austenite amount 1% or less, hot tensile test It is a high hardness precipitation hardening stainless steel excellent in manufacturability, characterized in that the temperature range in which the drawing (RA) in (Gleeble test) is 60% or more is 100 ° C. or more.
5.00 ≦ Ni eq ≦ 9.50 Formula (1)
Ni eq ≦ −0.83 × Cr eq +25.5 formula (2)
However, Ni eq = [% Ni] + 30 × ([% C] + [% N]) + 0.5 × [% Mn] + 0.3 × [% Cu], and Cr eq = [% Cr] + [[ % Mo] + 1.5 × [% Si] + 0.5 × [% Nb].
In addition, the numerical value (% by mass) of the content of the corresponding element is substituted for [% M] above.
第３の手段では、第１の手段の化学成分に加えて、質量％で、Ｃａ：０．０００１〜０．０２５０％、Ｍｇ：０．０００１〜０．０２５０％、Ｂ：０．０００１〜０．０２５０％から選択したいずれか１種または２種以上を含有し、残部Ｆｅおよび不可避不純物からなり、下記に記載の式（１）および式（２）を満足し、硬さが５５ＨＲＣ以上、残留オーステナイト量が１％以下、熱間引張試験（グリーブル試験）における絞り（ＲＡ）が６０％以上となる温度の範囲が１００℃以上であることを特徴とする製造性に優れた高硬度析出硬化型ステンレス鋼である。
５．００≦Ｎｉeq≦９．５０・・・式（１）
Ｎｉeq≦−０．８３×Ｃｒeq＋２５．５・・・式（２）
ただし、Ｎｉeq＝［％Ｎｉ］＋３０×（［％Ｃ］＋［％Ｎ］）＋０．５×［％Ｍｎ］＋０．３×［％Ｃｕ］であり、Ｃｒeq＝［％Ｃｒ］＋［％Ｍｏ］＋１．５×［％Ｓｉ］＋０．５×［％Ｎｂ］である。
なお、上記の［％Ｍ］には、いずれも対応する元素の含有量の数値（質量％）が代入される。
In the third means, in addition to the chemical component of the first means, by mass%, Ca: 0.0001 to 0.0250%, Mg: 0.0001 to 0.0250%, B: 0.0001 to 0 And any one or more selected from 0. 250%, the balance being composed of Fe and unavoidable impurities, satisfying Formula (1) and Formula (2) described below, having a hardness of 55 HRC or more, residual High hardness precipitation hardening type excellent in manufacturability characterized in that the temperature range at which the austenite content is 1% or less and the reduction (RA) in the hot tension test (grey test) is 60% or more is 100 ° C. or more Stainless steel.
5.00 ≦ Ni eq ≦ 9.50 Formula (1)
Ni eq ≦ −0.83 × Cr eq +25.5 formula (2)
However, Ni eq = [% Ni] + 30 × ([% C] + [% N]) + 0.5 × [% Mn] + 0.3 × [% Cu], and Cr eq = [% Cr] + [ % Mo] + 1.5 × [% Si] + 0.5 × [% Nb].
The numerical value (mass%) of the content of the corresponding element is substituted for the above [% M].
第４の手段では、第１の手段の化学成分に加えて、質量％で、Ａｌ：０．００１〜０．１５０％、Ｎｂ：０．０１〜２．００％、Ｎ：０．００２〜０．０５０％、Ｓ：０．００１〜０．１００％から選択したいずれか１種または２種以上を含有し、さらに、質量％で、Ｃａ：０．０００１〜０．０２５０％、Ｍｇ：０．０００１〜０．０２５０％、Ｂ：０．０００１〜０．０２５０％から選択したいずれか１種または２種以上を含有し、残部Ｆｅおよび不可避不純物からなり、下記に記載の式（１）および式（２）を満足し、硬さが５５ＨＲＣ以上、残留オーステナイト量が１％以下、熱間引張試験（グリーブル試験）における絞り（ＲＡ）が６０％以上となる温度の範囲が１００℃以上であることを特徴とする製造性に優れた高硬度析出硬化型ステンレス鋼である。
５．００≦Ｎｉeq≦９．５０・・・式（１）
Ｎｉeq≦−０．８３×Ｃｒeq＋２５．５・・・式（２）
ただし、Ｎｉeq＝［％Ｎｉ］＋３０×（［％Ｃ］＋［％Ｎ］）＋０．５×［％Ｍｎ］＋０．３×［％Ｃｕ］であり、Ｃｒeq＝［％Ｃｒ］＋［％Ｍｏ］＋１．５×［％Ｓｉ］＋０．５×［％Ｎｂ］である。
なお、上記の［％Ｍ］には、いずれも対応する元素の含有量の数値（質量％）が代入される。
In the fourth means, in addition to the chemical components of the first means, by mass%, Al: 0.001 to 0.150%, Nb: 0.01 to 2.00%, N: 0.002 to 0 0.05%, S: 0.001 to 0.100%, or any one or more selected from Ca, 0.0001 to 0.0250%, Mg: 0.001%. It contains any one or more selected from 0001 to 0.0250%, B: 0.0001 to 0.0250%, and consists of the balance Fe and unavoidable impurities, and the following formula (1) and formula Satisfying (2), having a hardness of 55 HRC or more, an amount of retained austenite of 1% or less, and a temperature range at which the reduction (RA) in the hot tension test (Greble test) is 60% or more is 100 ° C. or more High hardness precipitation hardened with excellent manufacturability Is the type of stainless steel.
5.00 ≦ Ni eq ≦ 9.50 Formula (1)
Ni eq ≦ −0.83 × Cr eq +25.5 formula (2)
However, Ni eq = [% Ni] + 30 × ([% C] + [% N]) + 0.5 × [% Mn] + 0.3 × [% Cu], and Cr eq = [% Cr] + [ % Mo] + 1.5 × [% Si] + 0.5 × [% Nb].
In addition, the numerical value (% by mass) of the content of the corresponding element is substituted for [% M] above.
本願の発明は、上記した手段とすることで、硬さが５５ＨＲＣ以上であり、耐候性があるので発銹し難く、残留オーステナイト量が１％以下であり、熱間引張試験の絞り（ＲＡ）が６０％以上となる温度の範囲が１００℃以上であり、熱間加工性に優れ、サブゼロ処理を要しない製造性に優れた、高硬度析出硬化型ステンレス鋼を製造することができる。 In the invention of the present application, by using the above-mentioned means, the hardness is 55 HRC or more, and since it has weather resistance, it is difficult to start, the amount of retained austenite is 1% or less, and the drawing of the hot tensile test (RA) The temperature range of 60% or higher is 100 ° C. or higher, and it is possible to manufacture a high hardness precipitation hardening stainless steel having excellent hot workability and excellent manufacturability that does not require sub-zero treatment.
本願の発明を実施するための形態について記載するに先立って、本願の上記の各手段におけるＦｅを除く化学成分の限定理由および式（１）および式（２）について以下に説明する。なお、化学成分の％は質量％である。 Before describing the mode for carrying out the invention of the present application, the reasons for limitation of chemical components other than Fe in the above respective means of the present application and the formulas (1) and (2) will be described below. In addition,% of a chemical component is the mass%.
Ｃ：０．０１〜０．１０％
Ｃは、鋼の強度および耐食性を維持するために必要な元素である。Ｃが０．０１％より少ないと強度不足となる。一方、Ｃが０．１０％より多いと耐食性が低下する。そこで、Ｃは０．０１〜０．１０％とする。
C: 0.01 to 0.10%
C is an element necessary to maintain the strength and corrosion resistance of the steel. If C is less than 0.01%, the strength is insufficient. On the other hand, when C is more than 0.10%, the corrosion resistance is lowered. Therefore, C is set to 0.01 to 0.10%.
Ｓｉ：０．３０〜２．００％
Ｓｉは、鋼の製錬時の脱酸材であり、かつ鋼の析出強化に寄与するために必要な元素である。Ｓｉが０．３０％より少ないと製錬時に脱酸剤として不足し、かつ鋼の析出強化元素として不足となる。一方、Ｓｉが２．００％より多いと、鋼の熱間加工性が低下する。そこで、Ｓｉは０．３０〜２．００％とする。
Si: 0.30 to 2.00%
Si is a deoxidizer at the time of smelting of steel, and is an element necessary for contributing to precipitation strengthening of steel. If Si is less than 0.30%, it will be insufficient as a deoxidizer at the time of smelting, and it will be insufficient as a precipitation strengthening element of steel. On the other hand, if the Si content is more than 2.00%, the hot workability of the steel is reduced. Therefore, Si is set to 0.30 to 2.00%.
Ｍｎ：０．０１〜１．００％
Ｍｎは、鋼の製錬時の脱酸材として必要な元素である。Ｍｎが０．０１％より少ないと製錬時に脱酸剤として不足する。一方、Ｍｎが１．００％より多いと、鋼の熱間加工性が低下する。そこで、Ｍｎは０．０１〜１．００％とする。
Mn: 0.01 to 1.00%
Mn is an element necessary as a deoxidizer at the time of smelting of steel. If Mn is less than 0.01%, it will be deficient as a deoxidizer during smelting. On the other hand, if the Mn content is more than 1.00%, the hot workability of the steel is reduced. Therefore, Mn is set to 0.01 to 1.00%.
Ｎｉ：４．００〜９．００％
Ｎｉは、鋼の析出強化に寄与する元素である。Ｎｉが４．００％より少ないと鋼の析出強化元素として不足する。一方、Ｎｉは高価な元素であるので、９．００％より多いとコストの増加となる。そこで、Ｎｉは４．００〜９．００％とする。
Ni: 4.00 to 9.00%
Ni is an element that contributes to the precipitation strengthening of steel. When Ni is less than 4.00%, it is insufficient as a precipitation strengthening element of steel. On the other hand, Ni is an expensive element, so if it exceeds 9.00%, the cost increases. Therefore, Ni is set to 4.00 to 9.00%.
Ｃｒ：８．００〜１４．５０％
Ｃｒは、鋼の耐食性に寄与する元素である。Ｃｒが８．００％より少ないと耐食性が低下する。一方、Ｃｒが１４．５０％より多いと、熱間加工性が低下し、かつＣｒは高価な元素であるのでコストの増加となる。そこで、Ｃｒは８．００〜１４．５０％とし、好ましくは８．００〜１３．００未満とする。
Cr: 8.00 to 14.50%
Cr is an element that contributes to the corrosion resistance of steel. If the Cr content is less than 8.00%, the corrosion resistance decreases. On the other hand, if the content of Cr is more than 14.50%, the hot workability is deteriorated, and the cost is increased because Cr is an expensive element. Therefore, Cr is set to 8.00 to 14.50%, preferably 8.00 to less than 13.00.
Ｍｏ：０．１０〜２．００％
Ｍｏは、鋼の耐食性に寄与する元素である。Ｍｏが０．１０％より少ないと耐食性が低下する。一方、Ｍｏが２．００より多いと熱間加工性が低下しかつ高価な元素であるのでコストの増加となる。そこで、Ｍｏは０．１０〜２．００％とする。
Mo: 0.10 to 2.00%
Mo is an element contributing to the corrosion resistance of steel. If the Mo content is less than 0.10%, the corrosion resistance decreases. On the other hand, if Mo is more than 2.00, the hot workability deteriorates and the cost is increased because it is an expensive element. Therefore, Mo is set to 0.10 to 2.00%.
Ｃｕ：０．５０〜４．００％
Ｃｕは、鋼の耐食性に寄与し、かつ析出強化に寄与する元素である。Ｃｕが０．５０％より少ないと鋼の耐食性が低下し、析出強化に寄与する元素として不足する。一方、Ｃｕが４．００％より多いと熱間加工性が低下する。そこで、Ｃｕは０．５０〜４．００％とする。
Cu: 0.50 to 4.00%
Cu is an element that contributes to the corrosion resistance of steel and contributes to precipitation strengthening. If the Cu content is less than 0.50%, the corrosion resistance of the steel is lowered and the element contributes to precipitation strengthening. On the other hand, if the Cu content is more than 4.00%, the hot workability is reduced. Therefore, Cu is set to 0.50 to 4.00%.
Ｔｉ：０．５０〜３．５０％
Ｔｉは、鋼の析出強化に寄与する元素である。Ｔｉが０．５０％より少ないと鋼の析出強化元素として不足する。一方、Ｔｉが３．５０％より多いと熱間加工性が低下しかつコストの増加となる。そこで、Ｔｉは０．５０〜３．５０％とする。
Ti: 0.50 to 3.50%
Ti is an element that contributes to the precipitation strengthening of steel. If Ti is less than 0.50%, it is insufficient as a precipitation strengthening element of steel. On the other hand, when the content of Ti is more than 3.50%, the hot workability is lowered and the cost is increased. Therefore, Ti is set to 0.50 to 3.50%.
次に、本発明に用いる選択的な化学成分の元素について以下に説明する。 Next, elements of selective chemical components used in the present invention will be described below.
Ａｌ：０．００１〜０．１５０％
Ａｌは、鋼の耐食性を低下させ、また、熱間加工性も低下させる成分である。そこで、０．１５０％を上限とする。他方、Ａｌを無理に低減しようとすると、かえってコスト高を招くため、経済的観点から０．００１％以上としてもよい。
Al: 0.001 to 0.150%
Al is a component that reduces the corrosion resistance of steel and also reduces the hot workability. Therefore, the upper limit is 0.150%. On the other hand, if it is attempted to reduce Al forcibly, the cost may be increased, and therefore, it may be 0.001% or more from the economical point of view.
Ｎｂ：０．０１〜２．００％
Ｎｂは、鋼の結晶粒粗大化を抑制する成分として添加しうる。もっとも、０．０１％より少ないと、結晶粒粗大化抑制の効果が得られない。他方、２．００％を超えると、熱間加工性が低下し、コストが増加することとなる。そこで、Ｎｂは、０．０１〜２．００％とする。
Nb: 0.01 to 2.00%
Nb can be added as a component which suppresses the coarsening of steel. However, if it is less than 0.01%, the effect of suppressing the grain coarsening can not be obtained. On the other hand, if it exceeds 2.00%, the hot workability will deteriorate and the cost will increase. Therefore, Nb is set to 0.01 to 2.00%.
Ｎ：０．００２〜０．０５０％
Ｎは、鋼の熱間加工性を低下させる成分である。また、０．０５０％を超えると、フェライトが不安定となる。そこで、０．０５０％を上限とする。他方、Ｎを無理に低減しようとすると、かえってコスト高を招くため、経済的観点から０．００２％以上としてもよい。
N: 0.002 to 0.050%
N is a component that reduces the hot workability of the steel. If it exceeds 0.050%, the ferrite becomes unstable. Therefore, 0.050% is made the upper limit. On the other hand, if N is to be reduced forcibly, the cost is increased. Therefore, it may be 0.002% or more from an economic viewpoint.
Ｓ：０．００１〜０．１００％
Ｓは、鋼の被削性向上のために添加しうる化学成分である。もっとも、０．００１％未満であると、少なすぎてその効果が得られない。他方、０．１００％を超えると、熱間加工性が低下する。そこで、Ｓは、０．００１〜０．１００％とする。
S: 0.001 to 0.100%
S is a chemical component that can be added to improve the machinability of steel. However, if it is less than 0.001%, the effect is not obtained because it is too small. On the other hand, if it exceeds 0.100%, the hot workability is reduced. Therefore, S is set to 0.001 to 0.100%.
なお、上記のＡｌ、Ｎｂ、Ｎ、およびＳの化学成分は、選択的に１種または２種以上が添加できる。 In addition, 1 type (s) or 2 or more types can selectively be added to said chemical component of Al, Nb, N, and S.
さらに、本発明に用いる上記以外の選択的な化学成分について以下に説明する。 Further, other selective chemical components used in the present invention will be described below.
Ｍｇ：０．０００１〜０．０２５０％
Ｍｇは、鋼の熱間加工性に寄与するために添加しうる化学成分である。もっとも、０．０００１％未満では、熱間加工性への寄与がみられない。他方、０．０２５０％を超えて過剰であると、かえって熱間加工性が低下する。そこで、０．０００１〜０．０２５０％とする。
Mg: 0.0001 to 0.0250%
Mg is a chemical component that can be added to contribute to the hot workability of steel. However, if it is less than 0.0001%, no contribution to the hot workability is observed. On the other hand, if it is in excess of 0.0250%, the hot workability is rather reduced. Therefore, the content is set to 0.0001 to 0.0250%.
Ｃａ：０．０００１〜０．０２５０％
Ｃａは、鋼の熱間加工性に寄与するために添加しうる化学成分である。もっとも、０．０００１％未満では、熱間加工性への寄与がみられない。他方、０．０２５０％を超えて過剰であると、かえって熱間加工性が低下する。そこで、０．０００１〜０．０２５０％とする。
Ca: 0.0001 to 0.0250%
Ca is a chemical component that can be added to contribute to the hot workability of steel. However, if it is less than 0.0001%, no contribution to the hot workability is observed. On the other hand, if it is in excess of 0.0250%, the hot workability is rather reduced. Therefore, the content is set to 0.0001 to 0.0250%.
Ｂ：０．０００１〜０．０２５０％
Ｂは、鋼の熱間加工性に寄与するために添加しうる化学成分である。もっとも、０．０００１％未満では、熱間加工性への寄与がみられない。他方、０．０２５０％を超えて過剰であると、かえって熱間加工性が低下する。そこで、０．０００１〜０．０２５０％とする。
B: 0.0001 to 0.0250%
B is a chemical component that can be added to contribute to the hot workability of the steel. However, if it is less than 0.0001%, no contribution to the hot workability is observed. On the other hand, if it is in excess of 0.0250%, the hot workability is rather reduced. Therefore, the content is set to 0.0001 to 0.0250%.
なお、上記のＭｇ、Ｃａ、およびＢの化学成分は、選択的に１種または２種以上が添加できる。 In addition, 1 type or 2 types or more can be selectively added to the above-mentioned chemical component of Mg, Ca, and B.
式（１）：５．００≦Ｎｉeq≦９．５０
式（１）のＮｉeqの値は、５．００以上の大きさ、かつ９．５０以下であることが必要である。式（１）が上記の条件を満足しないときは、鋼の熱間加工性が低下する。そこで、式（１）は、５．００≦Ｎｉeq≦９．５０とする。
ただし、上記式（１）におけるＮｉeq＝［％Ｎｉ］＋３０×（［％Ｃ］＋［％Ｎ］）+０．５×［％Ｍｎ］＋０．３×［％Ｃｕ］である。
Formula (1): 5.00 ≦ Ni eq ≦ 9.50
The value of Ni eq in the formula (1) needs to be 5.00 or more and 9.50 or less. When the equation (1) does not satisfy the above conditions, the hot workability of the steel decreases. Therefore, equation (1) is set to 5.00 ≦ Ni eq ≦ 9.50.
However, Ni eq = [% Ni] + 30 × ([% C] + [% N]) + 0.5 × [% Mn] + 0.3 × [% Cu] in the above formula (1).
式（２）：Ｎｉeq≦−０．８３×Ｃｒeq＋２５．５
式（２）に示すように、Ｎｉeqの値は、−０．８３×Ｃｒeq＋２５．５の値以下であることが必要である。式（２）が上記の条件を満足しないときは、残留オーステナイト量が大きくなるからである。そこで、式（２）は、Ｎｉeq≦−０．８３×Ｃｒeq＋２５．５とする。
ただし、Ｎｉeqは、Ｎｉeq＝［％Ｎｉ］＋３０×（［％Ｃ］＋［％Ｎ］）＋０．５×［％Ｍｎ］＋０．３×［％Ｃｕ］であり、さらに、Ｃｒeq＝［％Ｃｒ］＋［％Ｍｏ］＋１．５×［％Ｓｉ］＋０．５×［％Ｎｂ］である。
なお、（１）式および（２）式における［％Ｍ］（「Ｍ」は化学成分を示す。）の値はいずれも、質量％の数値の大きさ、すなわち、対応する元素の含有量の数値（質量％）が代入される。
Formula (2): Ni eq ≦ −0.83 × Cr eq +25.5
As shown in Expression (2), the value of Ni eq needs to be equal to or less than the value of −0.83 × Cr eq +25.5. This is because when the formula (2) does not satisfy the above condition, the amount of retained austenite becomes large. Therefore, Formula (2) is set to Ni eq ≦ −0.83 × Cr eq +25.5.
However, Ni eq is Ni eq = [% Ni] + 30 × ([% C] + [% N]) + 0.5 × [% Mn] + 0.3 × [% Cu], and further, Cr eq = It is [% Cr] + [% Mo] +1.5 * [% Si] +0.5 * [% Nb].
Note that the value of [% M] (“M” represents a chemical component) in the formulas (1) and (2) is the value of mass%, that is, the content of the corresponding element. A numerical value (mass%) is substituted.
次いで、本願の発明を実施するための形態について、実施例に基いて以下に説明する。 Next, modes for carrying out the invention of the present application will be described below based on examples.
表１に示す第１の手段の発明鋼の化学成分、表２に示す第２の手段の発明鋼の化学成分、表３に示す第３の手段の発明鋼および第４の手段の発明鋼の各化学成分の実施例鋼と、さらに、表４に示す比較鋼１（第１の手段に対する比較鋼）および比較鋼２（第２の手段に対する比較鋼）の各化学成分の比較例と、表５に示す比較鋼３（第３の手段に対する比較鋼）および比較鋼４（第４の手段に対する比較鋼）の各化学成分の比較例をそれぞれ有し、かつ、それぞれの残部であるＦｅおよび不可避不純物からなる実施例および比較例の各鋼を、それぞれ１００ｋｇＶＩＭ（真空誘導溶解炉）にて溶解して、インゴットに鋳造した。
これらのインゴットを１１５０℃で径２０ｍｍの棒鋼に鍛伸した。さらに、これらの棒鋼を９００〜１２００℃に１時間保持した後、水冷して固溶化熱処理を行った。さらに、これらの固溶化熱処理した棒鋼を３００〜８００℃で１時間保持した後、空冷して時効熱処理を行った。
Chemical composition of the invention steel of the first means shown in Table 1, Chemical composition of the invention steel of the second means shown in Table 2, Invention steel of the third means shown in Table 3, and Invention steel of the fourth means Example steel of each chemical component, and a comparative example and table of each chemical component of comparative steel 1 (comparative steel for the first means) and comparative steel 2 (comparative steel for the second means) shown in Table 4 5 has comparative examples of chemical components of comparative steel 3 (comparative steel for the third means) and comparative steel 4 (comparative steel for the fourth means) shown in FIG. Each of the steels of Examples and Comparative Examples made of impurities was melted in a 100 kg VIM (vacuum induction melting furnace) and cast into an ingot.
These ingots were forged at 1150 ° C. into 20 mm diameter bars. Furthermore, after hold | maintaining these steel bars at 900-1200 degreeC for 1 hour, water cooling was carried out and solution heat treatment was performed. Further, these solution heat-treated steel bars were held at 300 to 800 ° C. for 1 hour, and then air-cooled to perform aging heat treatment.
上記の時効熱処理後にそれぞれのサイズに調整した各素材から以下の試験を実施した。試験の結果は、それぞれの表１、表２、および表３の各請求鋼の発明鋼の化学成分と合せてそれら発明鋼の特性を示し、さらに、表４および表５に第１〜第４の手段の発明の比較例である比較鋼の化学成分と合わせてそれらの各特性を示す。
なお、各特性としては、（１）式、（２）式を満足するものは○、満足しないものは×とし、表１、表２、および表３、並びに表４および表５に表記した。また、耐候性試験では発銹したものを×、発銹しなかったものを○とし、表１、表２、および表３、並びに表４および表５に表記した。なお、表４および表５の下線部は本発明の範囲外であることを示している。
The following test was implemented from each raw material adjusted to each size after said aging heat treatment. The test results show the characteristics of the invention steels in combination with the chemical composition of the invention steels of each claimed steel in Table 1, Table 2, and Table 3, and Tables 4 and 5 show the characteristics of the first to fourth examples. In addition to the chemical composition of the comparative steel which is a comparative example of the invention of the means of, the respective properties thereof are shown.
In addition, as each characteristic, what satisfied (1) Formula and (2) Formula was made into (circle) and what is not satisfied was made into x, and it described in Table 1, Table 2, Table 3, and Table 4 and Table 5. Also, in the weather resistance test, those that developed were marked x, and those that were not generated were marked ○, and the results are shown in Table 1, Table 2, Table 3, and Tables 4 and 5. The underlined parts in Tables 4 and 5 indicate that they are out of the scope of the present invention.
評価項目は、各発明鋼および各比較鋼のＮｉeqとＣｒeq、並びに、時効のピーク硬さ（ＨＲＣ）、耐候性（塩水噴霧試験で、５０ｐｐｍＮａＣｌを３５℃で１６時間噴霧による発銹無しを○、発銹有りを×）、残留オーステナイト量（％）、および熱間加工性（グリーブル試験）の絞り（ＲＡ）が６０％以上となる温度（℃）とした。 Evaluation items were Ni eq and Cr eq of each invention steel and each comparative steel, peak hardness of aging (HRC), weather resistance (in salt spray test, 50 ppm NaCl without spraying for 16 hours at 35 ° C.) (Circle), it was set as the temperature (degreeC) from which the drawing (RA) of austenite amount (%) and hot workability (Gleeble test) became 60% or more.
評価方法は、Ｎｉeq（すなわちＮｉ当量）、Ｃｒeq（すなわちＣｒ当量）、マルテンサイト開始温度であるＭｓ点（℃）、式（１）および式（２）の各値の大きさと、これらの値に関連する、時効熱処理を行った時効硬さにおけるピーク硬さ、耐候性、残留オーステナイト量である残留γ量、および熱間加工性における絞りすなわちＲＡ６０％以上となる温度をそれぞれ以下に示す手段により測定した。 The evaluation method is as follows: Ni eq (ie Ni equivalent), Cr eq (ie Cr equivalent), Ms point (° C.) which is the martensitic start temperature, the magnitude of each value of formula (1) and formula (2) The peak hardness, the weather resistance, the residual γ amount which is the amount of retained austenite, and the reduction in the hot workability, ie, the temperature at which RA 60% or more becomes, are shown below. It was measured by.
すなわち、時効硬さにおけるピーク硬さでは、上記の種々の時効処理を施した丸棒を用い、鍛伸方向に垂直な断面の中周部におけるロックウェル硬さを測定し、得られた硬さのうち最も大きな値のものをピーク硬さとし、その値がＨＲＣ５５以上であるものを良好であると判断した。 That is, for the peak hardness in aging hardness, using the round bars subjected to the various aging treatments described above, the Rockwell hardness at the middle periphery of the cross section perpendicular to the forging direction was measured, and the obtained hardness Among the above, the highest hardness was taken as the peak hardness, and it was judged that the hardness was HRC 55 or higher.
耐候性（塩水噴霧試験で、５０ｐｐｍＮａＣｌを３５℃で１６時間噴霧による）では、上記の種々の時効処理を施した丸棒を径１２ｍｍ、長さ２１ｍｍのサイズに調整し、耐候性試験を実施した。具体的には、試験片の表面に所定の濃度および温度の塩水を所定の時間噴霧し続け、試験後に、洗浄した試験片の表面の発銹の有無を調査した。 For weather resistance (salt spray test, 50 ppm NaCl by spraying for 16 hours at 35 ° C.), the above-mentioned various aged round bars were adjusted to a size of 12 mm in diameter and 21 mm in length, and a weather resistance test was conducted. . Specifically, salt water of a predetermined concentration and temperature was continued to be sprayed on the surface of the test piece for a predetermined time, and after the test, the surface of the cleaned test piece was examined for the presence or absence of sprouting.
残留オーステナイト量すなわち残留γ量では、上記の種々の時効処理を施した丸棒を用い、鍛伸方向に垂直な断面の中周部における残留オーステナイト量を測定した。測定には、湾曲ＩＰＸ線回折装置ＲＩＮＴ ＲＡＰＩＤ II（株式会社リガク、日本）を用いた。 With respect to the amount of retained austenite, that is, the amount of retained γ, the amount of retained austenite in the middle periphery of the cross section perpendicular to the forging direction was measured using the round bars subjected to the above various aging treatments. For measurement, a curved IP X-ray diffractometer RINT RAPID II (Rigaku, Japan) was used.
熱間加工性（グリーブル試験）における絞りすなわちＲＡ６０％以上の得られる温度では、上記の種々の時効処理を施した丸棒を、径８ｍｍ、長さ１００ｍｍのサイズの試験片に調整し、通電加熱による熱間引張試験（グリーブル試験）を実施した。試験温度は８００〜１３５０℃まで２５℃毎とし、破断後の試験片の熱間加工性における絞りＲＡが６０％以上である温度域を算出した。その温度域が１００℃以上のものを良好であると判断した。 In the hot workability (Gleeble test), at the temperature at which RA is 60% or more, the round bar subjected to the above-mentioned various aging treatments is adjusted to a test piece having a diameter of 8 mm and a length of 100 mm. A hot tensile test (Gleeble test) was performed. The test temperature was every 25 ° C. up to 800 to 1350 ° C., and a temperature range in which the reduction RA in the hot workability of the test piece after breakage was 60% or more was calculated. Those having a temperature range of 100 ° C. or higher were judged good.
表１、表２および表３に示すように、本願の第１〜第４の手段の各Ｎｏ．の発明鋼は、表中の式（１）の欄には、式（１）を満足する場合を○として評価した。
なお、式（１）とは、５．００≦Ｎｉeq≦９．５０である。
さらに、表中の式（２）の列には、式（２）を満足する場合を○として評価した。
式（２）とは、Ｎｉeq≦−０．８３×Ｃｒeq＋２５．５である。
なお、Ｎｉeq＝［％Ｎｉ］＋３０×（［％Ｃ］＋［％Ｎ］）＋０．５×［％Ｍｎ］＋０．３×［％Ｃｕ］であり、Ｃｒeq＝［％Ｃｒ］＋［％Ｍｏ］＋１．５×［％Ｓｉ］＋０．５×［％Ｎｂ］である。
As shown in Table 1, Table 2 and Table 3, each No. of each of the first to fourth means of the present application. In the steel of the invention, in the column of the formula (1) in the table, the case where the formula (1) was satisfied was evaluated as ○.
In addition, with Formula (1), it is 5.00 <= Nieq <= 9.50.
Furthermore, in the column of the formula (2) in the table, the case where the formula (2) is satisfied was evaluated as “◯”.
Formula (2) is Ni eq ≦ −0.83 × Cr eq +25.5.
Note that Ni eq = [% Ni] + 30 × ([% C] + [% N]) + 0.5 × [% Mn] + 0.3 × [% Cu], and Cr eq = [% Cr] + [[ % Mo] + 1.5 × [% Si] + 0.5 × [% Nb].
本願の第１〜第４の手段の各Ｎｏ．の発明鋼の特性について
表１、表２、および表３における、Ｎｉeqの値はいずれも５．００以上９．５０以下である。さらに、Ｃｒeqの値は、Ｎｉeqの値に応じて変動し、９．４〜１５．７である。
また、Ｍｓ点（マルテンサイト変態開始温度）は１０６〜２６２℃である。さらに、式（１）および、式（２）を満足するものは○と表示しているとおり、いずれも双方の式を満足する値となっている。
Each No. of the first to fourth means of the present application. The properties of Ni eq in Tables 1, 2 and 3 are all 5.00 or more and 9.50 or less. Furthermore, the value of Cr eq varies according to the value of Ni eq and is 9.4 to 15.7.
Moreover, Ms point (martensitic transformation start temperature) is 106-262 degreeC. Furthermore, those satisfying the formula (1) and the formula (2) are values satisfying both formulas as indicated by ◯.
そして、これらを満足する表１、表２、および表３の第１〜第４の手段の各発明鋼では、以下の様な特性を備えている。時効熱処理を行った時効硬さにおけるピーク硬さは５５ＨＲＣ以上であり、耐候性は塩水噴霧試験において発銹が無く、これらを○で示し、残留オーステナイト量すなわち残留γ量は１．０％以下であり、さらに熱間引張試験（グリーブル試験）における絞り（ＲＡ）が６０％以上となる温度は１００℃以上である。 And each invention steel of the 1st-4th means of Table 1, Table 2, and Table 3 which satisfy | fills these is equipped with the following characteristics. The peak hardness in the aging hardness after the aging heat treatment is 55 HRC or more, the weather resistance is not ignited in the salt spray test, these are indicated by ○, and the residual austenite amount, that is, the residual γ amount is 1.0% or less. Furthermore, the temperature at which the reduction (RA) in the hot tension test (greed test) is 60% or more is 100 ° C. or more.
以上の表１、表２、および表３の第１〜第４の手段の各発明鋼に対して、表４および表５に示す、これらと同順で対応する比較鋼１、比較鋼２、比較鋼３、比較鋼４の各Ｎｏ．についての上記試験の評価として、第１〜第４の手段の各発明の有する特性の範囲から外れる特性について以下に順次記載する。 Comparative steel 1 and comparative steel 2 shown in Table 4 and Table 5 in the same order as those in the invention steels of the first to fourth means of the above Table 1, Table 2 and Table 3 Each No. of Comparative Steel 3 and Comparative Steel 4 As an evaluation of the above-mentioned test for (1) to (4), the characteristics out of the range of the characteristics possessed by each invention of the first to fourth means are sequentially described below.
先ず、第１の手段に対応する比較鋼１のＮｏ．１〜１５について、以下に説明する。
Ｎｏ．１は、マルテンサイト開始温度であるＭｓ点が６１℃と１００℃未満の低さであるので、残留オーステナイト量（すなわち表１の残留γ量）が２．４％で、本願発明の規定の１．０％より多く、熱間加工性の絞りＲＡは６０％以上となる温度の下限値の１００℃に満たず、２５℃と極めて低い。
Ｎｏ．２は、Ｃの含有量が０．１２％と本願発明の範囲より多く、Ｎｉeqが本願発明の９．５０より高い１０．５８で、Ｍｓ点が６９℃と１００℃未満の低さで、式（１）を満たしていないので×で、耐候性も×で、残留オーステナイト量（残留γ量）が２．８％で本願発明に規定の１．０％より多く、熱間加工性の絞りＲＡが６０％以上となる温度範囲が１００℃未満の７５℃と低い。
Ｎｏ．３は、Ｓｉの含有量が０．２０％と本願発明の範囲より少なく、時効処理のピーク硬さが５３．８ＨＲＣと本願発明の５５ＨＲＣより低い。
Ｎｏ．４は、Ｓｉの含有量が２．１６％と本願発明の範囲より多く、Ｎｉeqが本願発明の９．５０より高い１０．３４で、式（１）を満たしておらず×で、熱間加工性の絞りＲＡは６０％以上となる温度範囲の下限値の１００℃に満たず５０℃と低い。
Ｎｏ．５は、Ｍｎの含有量が１．１７％と本願発明の範囲より多く、Ｎｉeqが本願発明における９．５０より高く９．８０であり、式（１）を満たしておらず×で、熱間加工性の絞りＲＡは６０％以上となる温度範囲の下限値である１００℃に満たず５０℃と低い。
Ｎｏ．６は、Ｎｉの含有量が３．６１％と本願発明の範囲の４．００％より少なく、時効処理のピーク硬さが５２．６ＨＲＣと本願発明における５５ＨＲＣより低い。
Ｎｏ．７は、Ｎｉの含有量が９．５２％と本願発明の範囲の９．００％より多く、Ｎｉeqが本願発明における９．５０より高く、１２．１０で、Ｍｓ点が５２℃と１００℃未満の低さで、式（１）を満たして織らず×で、残留オーステナイト量（残留γ量）が５．２％で本願発明の規定の１．０％より多く、熱間加工性の絞りＲＡは６０％以上となる温度範囲の下限値の１００℃に満たず７５℃と低い。
Ｎｏ．８は、Ｃｒの含有量が４．０３％と本願発明の範囲の８．００％より少なく、耐候性が×である。
Ｎｏ．９は、Ｃｒの含有量が１４．８８％と本願発明の範囲の１４．５０％より多く、熱間加工性が低く、コスト増となる。
Ｎｏ．１０は、Ｍｏの含有量が０．０４％と本願発明の範囲の０．１０％より少なく、Ｎｉeqが９．５１と、本願発明の９．５０よりやや高い値で式（１）を満たしておらず×で、耐候性も×で、熱間加工性の絞りＲＡが６０％以上となる温度範囲が１００℃未満で７５℃と低い。
Ｎｏ．１１は、Ｍｏの含有量が２．１９％と本願発明の２．００％より多く、コスト高で、Ｎｉeqが１１．０１と本願発明の９．５０より高く、式（１）を満たしていないので×であり、熱間加工性の絞りＲＡは６０％以上となる温度範囲の下限値である１００℃に満たず、５０℃と低い。
Ｎｏ．１２は、Ｃｕの含有量が０．３２％と本願発明の０．５０％より少なく、時効処理のピーク硬さが５３．２ＨＲＣと本願発明における５５ＨＲＣより低い。
Ｎｏ．１３は、Ｃｕの含有量が０．４３％と本願発明の４．００％より多く、Ｎｉeqが９．８５と本願発明の９．５０より高く、式（１）を満たしておらず×で、熱間加工性の絞りＲＡは６０％以上となる温度の下限値である１００℃に満たず、７５℃と低い。
Ｎｏ．１４は、Ｔｉの含有量が０．１２％と本願発明の下限値の０．５０％より少なく、Ｎｉeqが１０．３１と本願発明の９．５０より高く、式（１）を満たしておらず×で、時効処理のピーク硬さが５２．９ＨＲＣと本願発明における５５ＨＲＣより低く、熱間加工性の絞りＲＡは６０％以上となる温度範囲の下限値である１００℃に満たず５０℃と低い。
Ｎｏ．１５は、Ｔｉの含有量が３．８０％と本願発明の上限値の３．５０％より多く、Ｎｉeqが１０．００と本願発明における９．５０より高く、式（１）を満たしておらず×で、熱間加工性の絞りＲＡは６０％以上となる温度範囲の下限値である１００℃に満たず、７５℃と低い。
First, the No. of comparative steel 1 corresponding to the first means. 1 to 15 will be described below.
No. No. 1 is a martensite start temperature Ms point as low as 61 ° C. and less than 100 ° C., so the amount of retained austenite (that is, the amount of residual γ in Table 1) is 2.4%. More than 0.0%, the hot workability RA is less than 100 ° C., which is the lower limit of the temperature at which the hot workability is 60% or more, and is extremely low at 25 ° C.
No. 2 has a C content of 0.12%, which is higher than the range of the present invention, Ni eq is 10.58 higher than 9.50 of the present invention, and the Ms point is low at 69 ° C. and less than 100 ° C. Since the formula (1) is not satisfied, it is ×, the weather resistance is ×, the amount of retained austenite (residual γ amount) is 2.8%, which is larger than 1.0% defined in the present invention, and the hot workability is reduced. The temperature range where RA is 60% or more is as low as 75 ° C., which is less than 100 ° C.
No. No. 3 has a Si content of 0.20%, which is less than the range of the present invention, and the peak hardness of aging treatment is 53.8 HRC, which is lower than 55 HRC of the present invention.
No. 4 is more than the range of the present invention, the content of Si is 2.16%, Ni eq is 10.34 higher than 9.50 of the present invention, X does not satisfy the formula (1), and hot The workability restriction RA is less than 100 ° C., the lower limit of the temperature range of 60% or more, and is as low as 50 ° C.
No. 5 is 1.17%, which is more than the range of the present invention, Ni eq is higher than 9.50 in the present invention, and 9.80, and does not satisfy the formula (1). The drawability RA during interprocessability is less than 100 ° C., which is the lower limit value of the temperature range where it is 60% or more, and as low as 50 ° C.
No. 6 has a Ni content of 3.61%, which is less than 4.00% of the range of the present invention, and the peak hardness of the aging treatment is 52.6 HRC, which is lower than 55 HRC in the present invention.
No. No. 7 has a Ni content of 9.52%, which is more than 9.00% of the range of the present invention, Ni eq is higher than 9.50 in the present invention, 12.10, and the Ms point is 52 ° C and 100 ° C. Less than, not satisfying the formula (1) and not woven, and the amount of retained austenite (residual γ amount) is 5.2%, which is larger than 1.0% defined in the present invention, and the hot workability is reduced. RA is as low as 75 ° C., which is less than 100 ° C., which is the lower limit of the temperature range at which 60% or more will occur.
No. 8 has a Cr content of 4.03%, which is less than 8.00% of the range of the present invention, and the weather resistance is x.
No. No. 9 has a Cr content of 14.88%, which is more than 14.50% of the range of the present invention, has low hot workability, and increases costs.
No. No. 10 satisfies the formula (1) with a Mo content of 0.04%, which is less than 0.10% of the range of the present invention, and Ni eq of 9.51, which is slightly higher than 9.50 of the present invention. The temperature range where the hot workability RA is 60% or more is less than 100 ° C. and as low as 75 ° C.
No. No. 11 has a Mo content of 2.19%, which is higher than the 2.00% of the present invention, is expensive, Ni eq is 11.01, which is higher than 9.50 of the present invention, and satisfies the formula (1). Therefore, the hot workability reduction RA is less than 100 ° C., which is the lower limit of the temperature range of 60% or more, and is as low as 50 ° C.
No. No. 12 has a Cu content of 0.32%, which is less than 0.50% of the present invention, and an aging treatment peak hardness of 53.2 HRC, which is lower than 55 HRC in the present invention.
No. No. 13 has a Cu content of 0.43%, which is higher than 4.00% of the present invention, Ni eq is 9.85, which is higher than 9.50 of the present invention, and does not satisfy formula (1). The drawing RA for hot workability is less than 100 ° C., which is the lower limit of the temperature at which the temperature becomes 60% or more, and is as low as 75 ° C.
No. No. 14 has a Ti content of 0.12%, which is less than the lower limit of 0.50% of the present invention, Ni eq is 10.31, which is higher than 9.50 of the present invention, and does not satisfy Equation (1). The peak hardness of aging treatment is 52.9 HRC, which is lower than 55 HRC in the present invention, and the reduction RA of hot workability is 60 ° C. or less, which is the lower limit of the temperature range of 60% or more. Low.
No. No. 15 has a Ti content of 3.80%, which is more than the upper limit of 3.50% of the present invention, Ni eq is 10.00, which is higher than 9.50 of the present invention, and does not satisfy the formula (1). The hot workability RA is less than 100 ° C., which is the lower limit of the temperature range of 60% or more, and is as low as 75 ° C.
次いで、第２の手段に対応する比較鋼２のＮｏ．１６〜２１について以下に説明する。
Ｎｏ．１６は、Ａｌの含有量が０．１８６％と本願発明の上限値の０．１５０％より多い。しかしながら、Ａｌ以外の元素は規定の範囲内であるので、Ｎｉeq、Ｃｒeq、Ｍｓ点、式（１）、式（２）、時効硬さ（ピーク硬さ）、耐候性、残留オ−ステナイト量（残留γ量）、および熱間加工性の絞りＲＡに格別に影響は見られない。
Ｎｏ．１７は、Ｎｂの含有量が２．０９％と本願発明の上限値の２．００％より多い。そこで、Ｎｉeqが９．５２で本願発明の９．５０よりやや高い値であり、式（１）を満たしておらず×で、熱間加工性の絞りＲＡは６０％以上となる温度範囲の下限値である１００℃に満たず、７５℃と低い。
Ｎｏ．１８は、Ｎの含有量が０．０８４％と本願発明の上限の０．０５０％より多い。そこで、Ｎｉeqが１０．２５と本願発明における９．５０より高く、式（１）を満たしておらず×で、熱間加工性の絞りＲＡは６０％以上となる温度範囲の下限値である１００℃に満たず、７５℃と低い。
Ｎｏ．１９は、Ｓの含有量が０．１４５％と本願の上限の０．１００％より多い。そこで、熱間加工性の絞りＲＡは６０％以上となる温度範囲の下限値である１００℃に満たず、２５℃と極めて低い。
Ｎｏ．２０は、Ｎｂの含有量が２．１４％と本願発明の上限値の２．００％より多い。一方、Ｎを含有しているが、その含有量は本願発明の上限の０．０５０％以下の範囲内である。そこで、Ｎｉeqが９．６７と本願発明の９．５０より高く、式（１）を満たしておらず×で、熱間加工性の絞りＲＡは６０％以上となる温度範囲の下限値である１００℃に満たず、７５℃と低い。
Ｎｏ．２１は、Ｓの含有量が０．１２２％と本願発明の上限の０．１００％より多く、Ｎｂを含有しているが、その含有量は１．６９％と本願発明の０．０１〜２．００％の範囲内で、さらにＮを含有しているが、その含有量は本願の上限の０．０５０％より多い。そこで、Ｎｉeqは９．８０と本願発明の９．５０より高く、式（１）を満たしておらず×であり、熱間加工性の絞りＲＡは６０％以上となる温度範囲の下限値である１００℃に満たず、２５℃と極めて低い。
Subsequently, No. of comparative steel 2 corresponding to the second means. 16 to 21 will be described below.
No. In the No. 16, Al content is 0.186%, which is more than 0.150% of the upper limit value of the present invention. However, since elements other than Al are within the specified range, Ni eq , Cr eq , Ms point, formula (1), formula (2), aging hardness (peak hardness), weatherability, residual austenite The amount (residual γ amount) and the hot-working draw reduction RA are not significantly affected.
No. In No. 17, the Nb content is 2.09%, which is more than the upper limit of 2.00% of the present invention. Therefore, Ni eq is 9.52, which is slightly higher than 9.50 of the present invention, does not satisfy the formula (1), and the hot workability restriction RA is 60% or more in the temperature range. It does not reach the lower limit of 100 ° C and is as low as 75 ° C.
No. The content of N in the No. 18 is 0.084%, which is more than the upper limit of 0.050% of the present invention. Therefore, Ni eq is 10.25, which is higher than 9.50 in the present invention, does not satisfy the formula (1), and the hot workability reduction RA is the lower limit value of the temperature range of 60% or more. It is less than 100 ° C and as low as 75 ° C.
No. In the case of No. 19, the content of S is 0.145%, which is more than the upper limit of 0.100% of the present application. Thus, the hot-work reduction RA does not reach 100 ° C., which is the lower limit value of the temperature range of 60% or more, and is extremely low at 25 ° C.
No. In No. 20, the content of Nb is 2.14%, which is more than 2.00% of the upper limit value of the present invention. On the other hand, although it contains N, its content is in the range of 0.050% or less of the upper limit of the present invention. Therefore, Ni eq is 9.67, which is higher than 9.50 of the present invention, does not satisfy Equation (1), and the hot workability reduction RA is the lower limit value of the temperature range of 60% or more. It is less than 100 ° C and as low as 75 ° C.
No. No. 21 has an S content of 0.122%, which is higher than the upper limit of 0.100% of the present invention, and contains Nb, but its content is 1.69%, 0.01-2 of the present invention. In the range of 0.000%, it further contains N, but the content is more than 0.050% of the upper limit of the present application. Therefore, Ni eq is 9.80, which is higher than 9.50 of the present invention, does not satisfy the formula (1), is x, and the hot workability restriction RA is the lower limit of the temperature range of 60% or more. It is less than a certain 100 ° C. and extremely low at 25 ° C.
次いで、第３の手段に対応する比較鋼３のＮｏ．２２〜２４について説明する。
Ｎｏ．２２は、Ｃａの含有量が０．０３１２％と本願発明の上限値の０．０２５０％より多く、Ｂの含有量が０．０３４０％と本願発明の上限の０．０２５０％より多い。そこで、熱間加工性の絞りＲＡは６０％以上となる温度範囲の下限値である１００℃に満たず、７５℃と低い。
Ｎｏ．２３は、Ｍｇの含有量が０．０２８９％と本願発明の上限値の０．０２５０％より多い。そこで、熱間加工性の絞りＲＡは６０％以上となる温度範囲の下限値である１００℃に満たず、７５℃と低い。
Ｎｏ．２４は、Ｍｇの含有量が０．０２７４％と本願発明の上限値の０．０２５０％より多く、さらにＢの含有量が０．０３４０％と本願発明の上限値の０．０２５０％より多い。そこで、Ｎｉeqは１１．３９と本願発明の上限値の９．５０より高く、Ｍｓ点が１０６℃よりも低い９２℃の低さであり、式（１）を満たしておらず×であり、残留オーステナイト量（残留γ量）が２．７％で本願発明の規定の１．０％を超えており、熱間加工性の絞りＲＡは６０％以上となる温度範囲の下限値である１００℃に満たず、５０℃と低い。
Subsequently, No. of comparative steel 3 corresponding to the third means. 22 to 24 will be described.
No. In No. 22, the content of Ca is 0.0312%, which is more than 0.0250% of the upper limit value of the present invention, and the content of B is 0.0340%, which is more than 0.0250% of the upper limit of the present invention. Therefore, the hot-work reduction RA does not reach 100 ° C., which is the lower limit value of the temperature range of 60% or more, and is as low as 75 ° C.
No. No. 23 has an Mg content of 0.0289%, which is more than the upper limit of 0.0250% of the present invention. Therefore, the hot-work reduction RA does not reach 100 ° C., which is the lower limit value of the temperature range of 60% or more, and is as low as 75 ° C.
No. In No. 24, the Mg content is 0.0274%, which is more than 0.0250% of the upper limit value of the present invention, and the B content is 0.0340%, which is more than 0.0250% of the upper limit value of the present invention. Therefore, Ni eq is 11.39, which is higher than the upper limit value of 9.50 of the present invention, the Ms point is as low as 92 ° C. lower than 106 ° C., does not satisfy Equation (1), and is x, The retained austenite content (residual γ content) is 2.7% and exceeds 1.0% of the specification of the present invention, and the hot workability reduction RA is at the lower limit of the temperature range of 60% or more, 100 ° C. Less than 50 ° C.
最後に、第４の手段に対応する比較鋼４のＮｏ．２５〜３０について説明する。
Ｎｏ．２５は、Ａｌの含有量が０．０９９％と本願発明の上限値の０．１５０％以下の範囲内で、Ｎｂの含有量が０．９２％と本願発明の上限値の２．００％以下の範囲内で、Ｂの含有量が、０．０４０１％と本願発明の上限値の０．０２５０％を超えており、Ｎｉeqは１２．１２と本願発明の上限値の９．５０より高く、式（１）を満たしておらず×で、熱間加工性の絞りＲＡは６０％以上となる温度範囲の下限値である１００℃に満たず、７５℃と低い。
Ｎｏ．２６は、Ａｌを含有しておらず、Ｃａは０．００５２％と本願発明の０．０００１〜０．０２５０％の範囲内であるが、Ｍｇは０．０２９０％と本願発明の上限値の０．０２５０％より多く、熱間加工性の絞りＲＡは６０％以上となる温度範囲の下限値である１００℃に満たず、７５℃と低い。
Ｎｏ．２７は、Ａｌの含有量が０．０８３％と本願発明の上限値の０．１５０％の範囲内で、Ｎは０．０４１％と本願発明の０．００２〜０．０５０％の範囲内であるが、Ｍｇは０．０２６７％で本願発明の上限値の０．０２５０％より多いので、熱間加工性の絞りＲＡは６０％以上となる温度範囲の下限値である１００℃に満たず、５０℃と低い。
Ｎｏ．２８は、Ｓ含有量は０．０８９％と本願発明の０．００１〜０．１００％の範囲内で、Ａｌの含有量は０．０４１％と本願発明の０．００１〜０．１５０％の範囲内であるが、Ｃａは０．０３６１％と本願発明の上限値の０．０２５０％より多い。したがって、Ｎｉeqは１１．２１と本願発明の上限値の９．５０より高く、式（１）を満たしておらず×で、熱間加工性の絞りＲＡは６０％以上となる温度範囲の下限値である１００℃に満たず、５０℃と低い。
Ｎｏ．２９は、Ｓ含有量は０．０２６％と本願発明の０．００１〜０．１００％の範囲内で、Ａｌの含有量は無く、Ｎｂの含有量は０．２０％と本願発明の０．０１〜２．００％の範囲内で、さらにＭｇは０．０２１３％と本願発明の０．０１〜２．００％の範囲内で、Ｂは０．０２７４％で本願発明の上限値の０．０２５０％より多い。そこで、Ｎｉeqは１１．９０と本願発明の上限値の９．５０より高く、式（１）を満たしておらず×で、熱間加工性の絞りＲＡは６０％以上となる温度範囲の下限値である１００℃に満たず、７５℃と低い。
Ｎｏ．３０は、Ｓ含有量は０．０４７％と本願発明の０．００１〜０．１００％で、Ａｌは０．１８６％と本願発明の０．００１〜０．１５０％で、Ｃａは０．０２８４％で本願発明の上限値の０．０２５０％より多く、さらに、Ｍｇは０．０３１６％と本願発明の上限値の２．００％より多いが、Ｂは０．００３４％と本願発明の０．０００１〜０．０２５０％の範囲内である。そこで、熱間加工性の絞りＲＡは６０％以上となる温度範囲の下限値である１００℃に満たず、２５℃と極めて低い。
Finally, No. of comparative steel 4 corresponding to the fourth means. 25 to 30 will be described.
No. 25, within a range where the Al content is 0.099% and 0.150% or less of the upper limit of the present invention, and the Nb content is 0.92% and 2.00% or less of the upper limit of the present invention Within the range, the content of B exceeds 0.0401%, which is 0.0250% of the upper limit of the present invention, and Ni eq is 12.12, which is higher than 9.50 of the upper limit of the present invention, The expression (1) is not satisfied, and in the case of x, the reduction RA of the hot workability is less than 100 ° C. which is the lower limit value of the temperature range of 60% or more, and is as low as 75 ° C.
No. No. 26 does not contain Al, while Ca is 0.0052%, which is within the range of 0.0001 to 0.0250% of the present invention, while Mg is 0.0290%, which is 0 of the upper limit of the present invention. More than 0.0250%, the hot workability reduction RA is less than 100 ° C., which is the lower limit of the temperature range of 60% or more, and is as low as 75 ° C.
No. No. 27 has an Al content of 0.083% and 0.150% of the upper limit value of the present invention, and N has 0.041% and 0.002 to 0.050% of the present invention. However, since Mg is 0.0267%, which is more than 0.0250% of the upper limit of the present invention, the hot workability drawing RA is less than 100 ° C. which is the lower limit of the temperature range of 60% or more, As low as 50 ° C.
No. No. 28 has an S content of 0.089% and in the range of 0.001 to 0.100% of the present invention, and an Al content of 0.041% and 0.001 to 0.150% of the present invention. Although it is within the range, Ca is 0.0361%, which is more than 0.0250% of the upper limit of the present invention. Therefore, Ni eq is 11.21, which is higher than the upper limit of 9.50 according to the present invention, does not satisfy the formula (1), ×, and the lower limit of the temperature range in which the reduction RA of hot workability is 60% or more The value is less than 100 ° C. and is as low as 50 ° C.
No. No. 29 has an S content of 0.026% within the range of 0.001 to 0.100% of the present invention, no Al content, and an Nb content of 0.20%. Within the range of 01 to 2.00%, Mg is 0.0213%, within the range of 0.01 to 2.00% of the present invention, and B is 0.0274%, which is an upper limit of 0.02% of the present invention. More than 0250%. Therefore, Ni eq is 11.90, which is higher than the upper limit value of 9.50 of the present invention, does not satisfy the formula (1), and the hot work restriction RA is 60% or more. It does not reach the value of 100 ° C and is as low as 75 ° C.
No. No. 30 has an S content of 0.047% and 0.001 to 0.100% of the present invention, Al is 0.186% and 0.001 to 0.150% of the present invention, and Ca is 0.0284. % Is more than 0.0250% of the upper limit value of the present invention, and Mg is 0.0316%, which is more than 2.00% of the upper limit value of the present invention. It is in the range of 0001 to 0.0250%. Accordingly, the hot workability RA is less than 100 ° C., which is the lower limit of the temperature range of 60% or more, and is as low as 25 ° C.
Claims (4)
５．００≦Ｎｉeq≦９．５０・・・式（１）
Ｎｉeq≦−０．８３×Ｃｒeq＋２５．５・・・式（２）
ただし、Ｎｉeq＝［％Ｎｉ］＋３０×（［％Ｃ］＋［％Ｎ］）＋０．５×［％Ｍｎ］＋０．３×［％Ｃｕ］で、Ｃｒeq＝［％Ｃｒ］＋［％Ｍｏ］＋１．５×［％Ｓｉ］＋０．５×［％Ｎｂ］でる。
なお、上記の［％Ｍ］には、いずれも対応する元素の含有量の数値（質量％）が代入される。 In mass%, C: 0.01 to 0.10%, Si: 0.30 to 2.00%, Mn: 0.01 to 1.00%, Ni: 4.00 to 9.00%, Cr: 8.00 to 14.50%, Mo: 0.10 to 2.00%, Cu: 0.50 to 4.00%, Ti: 0.50 to 3.50%, balance Fe and inevitable impurities And a hardness of 55 HRC or more, a retained austenite amount of 1% or less, and a temperature of 100% or more at a drawing temperature of 60% or more in a hot tensile test (greable test). A high-hardness precipitation-hardened stainless steel excellent in manufacturability characterized by having a temperature of at least ° C.
5.00 ≦ Ni eq ≦ 9.50 Formula (1)
Ni eq ≦ −0.83 × Cr eq +25.5 formula (2)
However, Ni eq = [% Ni] + 30 × ([% C] + [% N]) + 0.5 × [% Mn] + 0.3 × [% Cu], and Cr eq = [% Cr] + [% Mo] + 1.5 × [% Si] + 0.5 × [% Nb].
In addition, the numerical value (% by mass) of the content of the corresponding element is substituted for [% M] above.
５．００≦Ｎｉeq≦９．５０・・・式（１）
Ｎｉeq≦−０．８３×Ｃｒeq＋２５．５・・・式（２）
ただし、Ｎｉeq＝［％Ｎｉ］＋３０×（［％Ｃ］＋［％Ｎ］）＋０．５×［％Ｍｎ］＋０．３×［％Ｃｕ］で、Ｃｒeq＝［％Ｃｒ］＋［％Ｍｏ］＋１．５×［％Ｓｉ］＋０．５×［％Ｎｂ］である。
なお、上記の［％Ｍ］には、いずれも対応する元素の含有量の数値（質量％）が代入される。 In addition to the chemical composition of claim 1, Al: 0.001 to 0.150%, Nb: 0.01 to 2.00%, N: 0.002 to 0.050%, and S: in mass%. Any one or more selected from 0.001 to 0.100% is contained, provided that Cr in the chemical composition of claim 1 is less than 8.00 to 13.00%. , Remainder of Fe and unavoidable impurities, satisfying the following formulas (1) and (2), having a hardness of 55 HRC or more, an amount of retained austenite of 1% or less, and a drawing of 60% in a hot tension test (greeble test) A high-hardness precipitation-hardened stainless steel excellent in manufacturability characterized by having a temperature of 100 ° C. or higher.
5.00 ≦ Ni eq ≦ 9.50 Formula (1)
Ni eq ≦ −0.83 × Cr eq +25.5 formula (2)
However, Ni eq = [% Ni] + 30 × ([% C] + [% N]) + 0.5 × [% Mn] + 0.3 × [% Cu] and Cr eq = [% Cr] + [% Mo] + 1.5 × [% Si] + 0.5 × [% Nb].
In addition, the numerical value (% by mass) of the content of the corresponding element is substituted for [% M] above.
５．００≦Ｎｉeq≦９．５０・・・式（１）
Ｎｉeq≦−０．８３×Ｃｒeq＋２５．５・・・式（２）
ただし、Ｎｉeq＝［％Ｎｉ］＋３０×（［％Ｃ］＋［％Ｎ］）＋０．５×［％Ｍｎ］＋０．３×［％Ｃｕ］で、Ｃｒeq＝［％Ｃｒ］＋［％Ｍｏ］＋１．５×［％Ｓｉ］＋０．５×［％Ｎｂ］である。
なお、上記の［％Ｍ］には、いずれも対応する元素の含有量の数値（質量％）が代入される。 In addition to the chemical component of claim 1, any one selected from Ca: 0.0001 to 0.0250%, Mg: 0.0001 to 0.0250%, B: 0.0001 to 0.0250% in mass% Containing one or more kinds, remaining balance Fe and unavoidable impurities, satisfying the following formulas (1) and (2), hardness 55 HRC or more, retained austenite amount 1% or less, hot A high-hardness precipitation-hardened stainless steel excellent in manufacturability characterized in that the temperature at which the drawing reaches 60% or more in a tensile test (greed test) is 100 ° C. or higher.
5.00 ≦ Ni eq ≦ 9.50 Formula (1)
Ni eq ≦ −0.83 × Cr eq +25.5 formula (2)
However, Ni eq = [% Ni] + 30 × ([% C] + [% N]) + 0.5 × [% Mn] + 0.3 × [% Cu], and Cr eq = [% Cr] + [% Mo] + 1.5 × [% Si] + 0.5 × [% Nb].
In addition, the numerical value (% by mass) of the content of the corresponding element is substituted for [% M] above.
５．００≦Ｎｉeq≦９．５０・・・式（１）
Ｎｉeq≦−０．８３×Ｃｒeq＋２５．５・・・式（２）
ただし、Ｎｉeq＝［％Ｎｉ］＋３０×（［％Ｃ］＋［％Ｎ］）＋０．５×［％Ｍｎ］＋０．３×［％Ｃｕ］で、Ｃｒeq＝［％Ｃｒ］＋［％Ｍｏ］＋１．５×［％Ｓｉ］＋０．５×［％Ｎｂ］である。
なお、上記の［％Ｍ］には、対応する元素の含有量の数値（質量％）が代入される。 In addition to the chemical composition of claim 1, Al: 0.001 to 0.150%, Nb: 0.01 to 2.00%, N: 0.002 to 0.050%, S: 0 by mass%. Or more selected from 0.001 to 0.100%, Ca: 0.0001 to 0.0250%, Mg: 0.0001 to 0.0250%, B: 0. The composition contains any one or more selected from 0001 to 0.0250%, consists of the balance Fe and unavoidable impurities, satisfies the formulas (1) and (2) described below, and has a hardness of 55 HRC The high-hardness precipitation-hardened stainless steel excellent in manufacturability characterized in that the amount of retained austenite is at most 1% and the temperature at which the reduction becomes 60% or more in the hot tensile test (greable test) is 100 ° C. or higher.
5.00 ≦ Ni eq ≦ 9.50 Formula (1)
Ni eq ≦ −0.83 × Cr eq +25.5 formula (2)
However, Ni eq = [% Ni] + 30 × ([% C] + [% N]) + 0.5 × [% Mn] + 0.3 × [% Cu], and Cr eq = [% Cr] + [% Mo] + 1.5 × [% Si] + 0.5 × [% Nb].
In addition, the numerical value (mass%) of the content of the corresponding element is substituted for the above [% M].
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63171857A (en) * | 1987-01-10 | 1988-07-15 | Nippon Yakin Kogyo Co Ltd | Manufacture of precipitation hardening-type stainless steel excellent in fatigue characteristic |
| JPH05112850A (en) * | 1991-04-26 | 1993-05-07 | Nippon Steel Corp | Precipitation hardening martensitic stainless steel excellent in workability |
| JPH05255734A (en) * | 1991-11-22 | 1993-10-05 | Nippon Steel Corp | Production of martensitic stainless steel minimal in cracking sensitivity |
| JP2002161343A (en) * | 2000-11-20 | 2002-06-04 | Hitachi Metals Ltd | Precipitation-hardening type martensitic stainless-steel with high strength superior in corrosion resistance |
| JP2017078195A (en) * | 2015-10-20 | 2017-04-27 | 山陽特殊製鋼株式会社 | High hardness stainless steel excellent in corrosion resistance and productivity |
-
2018
- 2018-01-23 JP JP2018008811A patent/JP6987651B2/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63171857A (en) * | 1987-01-10 | 1988-07-15 | Nippon Yakin Kogyo Co Ltd | Manufacture of precipitation hardening-type stainless steel excellent in fatigue characteristic |
| JPH05112850A (en) * | 1991-04-26 | 1993-05-07 | Nippon Steel Corp | Precipitation hardening martensitic stainless steel excellent in workability |
| JPH05255734A (en) * | 1991-11-22 | 1993-10-05 | Nippon Steel Corp | Production of martensitic stainless steel minimal in cracking sensitivity |
| JP2002161343A (en) * | 2000-11-20 | 2002-06-04 | Hitachi Metals Ltd | Precipitation-hardening type martensitic stainless-steel with high strength superior in corrosion resistance |
| JP2017078195A (en) * | 2015-10-20 | 2017-04-27 | 山陽特殊製鋼株式会社 | High hardness stainless steel excellent in corrosion resistance and productivity |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2021171698A1 (en) * | 2020-02-27 | 2021-09-02 | 日本冶金工業株式会社 | Precipitation-hardening martensitic stainless steel |
| JP2021134395A (en) * | 2020-02-27 | 2021-09-13 | 日本冶金工業株式会社 | Precipitation-hardening martensitic stainless steel |
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| JP6987651B2 (en) | 2022-01-05 |
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