JP2017078195A - High hardness stainless steel excellent in corrosion resistance and productivity - Google Patents
High hardness stainless steel excellent in corrosion resistance and productivity Download PDFInfo
- Publication number
- JP2017078195A JP2017078195A JP2015206051A JP2015206051A JP2017078195A JP 2017078195 A JP2017078195 A JP 2017078195A JP 2015206051 A JP2015206051 A JP 2015206051A JP 2015206051 A JP2015206051 A JP 2015206051A JP 2017078195 A JP2017078195 A JP 2017078195A
- Authority
- JP
- Japan
- Prior art keywords
- hardness
- corrosion resistance
- stainless steel
- steel
- less
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Abstract
Description
本発明は、自動車や船舶などのプロペラシャフト、ドライブシャフトおよび当てん装置のロールなどといった高硬度、高耐食性および高靭性が求められる部材として使用される耐食性および製造性に優れたステンレス鋼に関する。 The present invention relates to a stainless steel excellent in corrosion resistance and manufacturability used as a member requiring high hardness, high corrosion resistance and high toughness, such as propeller shafts for automobiles and ships, drive shafts and rolls of striking devices.
自動車用部材のシャフトや圧延用ロールといった用途に使用される材料では、高硬度、高靱性を必須の性能とし、さらに、これらの性能に加えて、様々な使用環境に対応できる耐食性も有するものが望まれている。ところで、ＳＵＳ４２０ｊ２に代表されるマルテンサイト系ステンレス鋼では、高硬度は確保できても、耐食性では耐食環境が限定される。一方、ＳＵＳ６３０やＳＵＳ６３１で代表される析出硬化系ステンレス鋼は良好な耐食性を示すが、硬さはマルテンサイト系ステンレス鋼の耐食性には及ばない上に、最高硬さが得られる加工熱処理条件も限られるため、製造上にも難がある。 Materials used for applications such as shafts for automobile members and rolls for rolling have high hardness and high toughness as essential performances, and in addition to these performances, they also have corrosion resistance that can be used in various usage environments. It is desired. By the way, in martensitic stainless steel represented by SUS420j2, even if high hardness can be secured, the corrosion resistance environment is limited in terms of corrosion resistance. On the other hand, precipitation hardened stainless steels represented by SUS630 and SUS631 exhibit good corrosion resistance, but the hardness is not as good as that of martensitic stainless steels, and the conditions of thermomechanical processing for obtaining the highest hardness are also limited. Therefore, there are difficulties in manufacturing.
他方、ＳＵＳ６３０の析出硬化系ステンレス鋼をベースとして、その化学成分のＳｉをＴｉ、Ｎｂ、Ｖ、Ｔａ、Ｎｉ及びＣｏとともに時効処理による金属間化合物のＧ相の複合析出により高硬度が得られる発明が提案されている（例えば、特許文献１、特許文献２参照。）。しかし、これらの提案の発明では金属間化合物のＧ相構成元素として高価なＣｏを化学成分として必須としている。しかも、これらの提案の発明では、さらに高い硬さが得られる熱処理範囲については考慮されていない。 On the other hand, based on precipitation hardening stainless steel of SUS630, high hardness can be obtained by complex precipitation of intermetallic compound G phase by aging treatment with Si, its chemical component, together with Ti, Nb, V, Ta, Ni and Co Has been proposed (see, for example, Patent Document 1 and Patent Document 2). However, these proposed inventions require expensive Co as a chemical component as a constituent element of the G phase of the intermetallic compound. In addition, these proposed inventions do not consider the heat treatment range in which higher hardness can be obtained.
さらに、マルテンサイト系析出硬化型のステンレス鋼の本来の特徴を失うことなく、被削性を飛躍的に改善した快削析出型ステンレス鋼が提案されている（例えば、特許文献３参照。）。しかし、この提案の快削析出型ステンレス鋼はスクラップの再利用性を加味しており、Ｃｕは積極的に添加していないので、硬さレベルが低く、高い時効硬さが得られる熱処理範囲が限定的である。 Furthermore, a free-cutting precipitation-type stainless steel has been proposed that has dramatically improved machinability without losing the original characteristics of martensitic precipitation-hardening stainless steel (see, for example, Patent Document 3). However, this proposed free-cutting precipitation type stainless steel takes into account the reusability of scrap, and Cu is not actively added, so there is a low heat level and a heat treatment range in which high aging hardness can be obtained. Limited.
自動車用部材のシャフトや圧延用ロールといった用途に使用される材料は、高硬度、高靱性を必須性能とし、さらに様々な使用環境に対応できる耐食性を有するものが望まれている。ところで、ＳＵＳ４２０Ｊ２に代表されるマルテンサイト系ステンレス鋼では、高硬度は確保できても、耐食環境は限定される。一方、ＳＵＳ６３０やＳＵＳ６３１で代表される析出硬化型ステンレス鋼は良好な耐食性を示すが、硬さはマルテンサイト系ステンレス鋼の硬さには及ばない。その上に、これらの析出硬化型ステンレス鋼は最高硬さが得られる加工熱処理条件も限られる。そのために、これらは製造性にも難がある。そこで、こうした現状では、解決しなければならない問題がある。 As materials used for applications such as shafts for automobile members and rolls for rolling, materials having high hardness and high toughness as essential properties and having corrosion resistance that can cope with various usage environments are desired. By the way, in the martensitic stainless steel represented by SUS420J2, the corrosion resistance environment is limited even though high hardness can be secured. On the other hand, precipitation hardening stainless steels represented by SUS630 and SUS631 exhibit good corrosion resistance, but the hardness does not reach the hardness of martensitic stainless steel. In addition, these precipitation-hardening stainless steels have limited heat treatment conditions for obtaining the highest hardness. Therefore, these also have difficulty in manufacturability. Therefore, in such a current situation, there is a problem that must be solved.
本願の発明が解決しようとする課題は、マルテンサイト系ステンレス鋼と析出硬化型ステンレス鋼の双方の特長を有し、さらに高硬度が得られる熱処理範囲が広く、製造性にも長けているので、耐食性および製造性に優れた高硬度ステンレス鋼を提供することである。 The problem to be solved by the invention of the present application has features of both martensitic stainless steel and precipitation hardening stainless steel, and further has a wide heat treatment range in which high hardness can be obtained, and is also excellent in manufacturability. It is to provide a high-hardness stainless steel excellent in corrosion resistance and manufacturability.
本願の発明の課題を解決するための手段は、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り、下記（１）式、（２）式、および（３）式を満足することを特徴とする耐食性および製造性に優れた高硬度ステンレス鋼である。
［Ｃｕ］＋２．３［Ｔｉ］＋２．４［Ｓｉ］≧５．３・・・（１）
［Ｃｒ］＋３［Ｍｏ］＋［Ｎｂ］＋［Ｔｉ］＋［Ｓｉ］＋［Ｎｉ］＋［Ｃｕ］−２６（［Ｃ］＋［Ｎ］）−１０．３≧１２．０・・・（２）
［Ｃｒ］＋１．５［Ｓｉ］＋［Ｍｏ］＋０．５［Ｎｂ］＋２［Ｔｉ］−０．５［Ｎｉ］−６．７（［Ｃ］＋［Ｎ］）≦１９．５・・・（３）
Means for solving the problems of the invention of the present application are, 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: 4.0-9.0%, Cr: 13.0-22.0%, Mo: 0.20-2.00%, Cu : 0.60 to 4.00%, Ti: 0.50 to 3.50%, Nb: 0.01 to 2.00%, N: 0.050% or less, the balance being Fe and inevitable impurities These are high hardness stainless steels excellent in corrosion resistance and manufacturability characterized by satisfying the following formulas (1), (2), and (3).
[Cu] +2.3 [Ti] +2.4 [Si] ≧ 5.3 (1)
[Cr] +3 [Mo] + [Nb] + [Ti] + [Si] + [Ni] + [Cu] −26 ([C] + [N]) − 10.3 ≧ 12.0. 2)
[Cr] +1.5 [Si] + [Mo] +0.5 [Nb] +2 [Ti] −0.5 [Ni] −6.7 ([C] + [N]) ≦ 19.5. (3)
本発明の手段の合金の組成範囲とすることおよび（１）式に限定することによりＣｕとＧ相（Ｎｉ16Ｔｉ6Ｓｉ7）の複合析出によって最高時効（ピーク時効）硬さである、時効硬さ≧５３ＨＲＣが得られ、かつ最高時効（ピーク時効）温度±５０℃の範囲で、時効硬さ≧４８ＨＲＣが得られ、さらに（２）式に限定することにより、最高時効（ピーク時効）硬さである、時効硬さ≧５３ＨＲＣを確保し、炭窒化物の析出を抑制して、優れた耐食性が得られ、また、さらに（３）式に限定することにより、最高時効（ピーク時効）硬さである、時効硬さ≧５３ＨＲＣを確保し、δフェライト量とマトリクスの脆化を抑制して良好な靱性が得られる。 The aging is the highest aging (peak aging) hardness due to the composite precipitation of Cu and G phase (Ni 16 Ti 6 Si 7 ) by limiting the composition range of the alloy of the means of the present invention to the formula (1). Hardness ≧ 53HRC is obtained, and aging hardness ≧ 48HRC is obtained in the range of maximum aging (peak aging) temperature ± 50 ° C. Furthermore, by limiting to the formula (2), the maximum aging (peak aging) hardness The aging hardness ≧ 53HRC is ensured, the precipitation of carbonitrides is suppressed, and excellent corrosion resistance is obtained. Further, by limiting to the formula (3), the maximum aging (peak aging) hardness is obtained. As a result, an aging hardness of ≧ 53 HRC is ensured, and the amount of δ ferrite and embrittlement of the matrix are suppressed, and good toughness can be obtained.
発明の実施するための形態を記載するに先立って、本願発明の課題を解決する手段における構成要件について記載する。この場合、各成分元素における％は、質量％である。 Prior to describing the mode for carrying out the invention, the constituent elements in the means for solving the problems of the present invention will be described. In this case,% in each component element is mass%.
Ｃ：０．０１〜０．１０％
Ｃは、鋼のγ安定元素で過剰δフェライトの生成を抑制し、良好な靱性を確保するために必要な元素である。このためには、Ｃは０．０１％以上が必要である。しかし、Ｃは０．１０％を超えて含有されると、炭窒化物の生成により鋼の耐食性が劣化する。そこで、Ｃは０．０１〜０．１０％とする。
C: 0.01 to 0.10%
C is a γ-stable element of steel and is an element necessary for suppressing the formation of excess δ ferrite and ensuring good toughness. For this purpose, C needs to be 0.01% or more. However, if C is contained in excess of 0.10%, the corrosion resistance of the steel deteriorates due to the formation of carbonitrides. Therefore, C is set to 0.01 to 0.10%.
Ｓｉ：０．３０〜２．００％
Ｓｉは、製鋼段階での脱酸剤であり、鋼に析出硬化粒子を生成する。このためには、Ｓｉは０．３０％以上が必要である。しかし、Ｓｉは２．００％を超えて含有されると、鋼の延性、δフェライトの生成およびマトリックスの脆化による靱性、並びに鋼の製造性が低下する。そこで、Ｓｉは０．３０〜２．００％、好ましくは、０．５０〜１．８０％とする。
Si: 0.30 to 2.00%
Si is a deoxidizer in the steelmaking stage, and generates precipitation hardening particles in the steel. For this purpose, Si needs to be 0.30% or more. However, if Si is contained in excess of 2.00%, the ductility of the steel, the toughness due to the formation of δ ferrite and the embrittlement of the matrix, and the manufacturability of the steel are lowered. Therefore, Si is 0.30 to 2.00%, preferably 0.50 to 1.80%.
Ｍｎ：０．０１〜１．００％
Ｍｎは、製鋼段階での脱酸剤である。このためには、Ｍｎは０．０１％以上が必要である。しかし、Ｍｎは１．００％を超えて含有されると、脱酸剤としての効果は飽和し、かつ、鋼に硫化物の生成を促進して鋼の耐食性を劣化する。そこで、Ｍｎは０．０１〜１．００％とし、好ましくは、０．１０〜０．８０％とする。
Mn: 0.01 to 1.00%
Mn is a deoxidizer in the steelmaking stage. For this purpose, Mn needs to be 0.01% or more. However, if Mn is contained in an amount exceeding 1.00%, the effect as a deoxidizing agent is saturated, and the formation of sulfide in the steel is promoted to deteriorate the corrosion resistance of the steel. Therefore, Mn is 0.01 to 1.00%, preferably 0.10 to 0.80%.
Ｐ：０．０４０％以下
Ｐは、不純物元素であり、鋼に０．０４０％を超えて含有されると、鋼の延性、靱性および熱間加工性が劣化する。そこで、Ｐは０．０４０％以下とし、好ましくは、０．０２０％以下とする。
P: 0.040% or less P is an impurity element. If the steel is contained in an amount exceeding 0.040%, the ductility, toughness and hot workability of the steel deteriorate. Therefore, P is set to 0.040% or less, preferably 0.020% or less.
Ｓ：０．０３０％以下
Ｓは、不純物元素であり、鋼に０．０３０％を超えて含有されると、鋼の延性、靱性および熱間加工性が劣化する。そこで、Ｓは０．０３０％以下とし、好ましくは、０．０２０％以下とする。
S: 0.030% or less S is an impurity element. If the steel is contained in an amount exceeding 0.030%, the ductility, toughness and hot workability of the steel deteriorate. Therefore, S is set to 0.030% or less, preferably 0.020% or less.
Ｎｉ：４．０〜９．０％
Ｎｉは、鋼のγ安定元素で過剰δフェライトの生成を抑制する一方で、良好な靱性を確保すると共に、焼入性の向上による均質微細組織を形成する元素である。このためには、Ｎｉは４．０％以上が必要である。しかし、９．０％を超えて含有されても、上記の効果が飽和し、かつ残留γ量の増大により鋼の硬さが軟化し、コスト高となる。そこで、Ｎｉは鋼のγ安定元素で過剰δフェライトの生成を抑制し、好ましくは、４．５〜７．５％とする。
Ni: 4.0-9.0%
Ni is a γ-stable element of steel that suppresses the formation of excess δ ferrite, while ensuring good toughness and forming a homogeneous microstructure by improving hardenability. For this purpose, Ni needs to be 4.0% or more. However, even if the content exceeds 9.0%, the above effect is saturated, and the hardness of the steel is softened due to an increase in the amount of residual γ, resulting in an increase in cost. Therefore, Ni is a γ-stable element of steel and suppresses the formation of excess δ ferrite, preferably 4.5 to 7.5%.
Ｃｒ：１３．０〜２２．０％
Ｃｒは、耐食性を向上させる元素である。このためには、Ｃｒは１３．０％以上が必要である。しかし、Ｃｒは２２．０％を超えて含有されると、耐食性向上の効果は飽和し、過剰のδフェライト生成し、脆化相の生成により靱性を劣化する。そこで、Ｃｒは１３．０〜２２．０％とし、好ましくは、１４．０〜２０．０％とする。
Cr: 13.0-22.0%
Cr is an element that improves the corrosion resistance. For this purpose, Cr needs to be 13.0% or more. However, if the Cr content exceeds 22.0%, the effect of improving the corrosion resistance is saturated, excessive δ ferrite is generated, and the toughness is deteriorated due to the formation of the embrittled phase. Therefore, Cr is set to 13.0 to 22.0%, preferably 14.0 to 20.0%.
Ｍｏ：０．２０〜２．００％
Ｍｏは、耐食性を向上させる元素である。このためには、Ｍｏは０．２０％以上が必要である。しかし、Ｍｏは高価な元素であるので、２．００％を超えて含有させると、コスト高となり、さらに、過剰のδフェライト生成し、脆化相の生成により靱性を劣化する。そこで、Ｍｏは０．２０〜２．００％とし、好ましくは、０．５０〜１．７０％とする。
Mo: 0.20 to 2.00%
Mo is an element that improves the corrosion resistance. For this purpose, Mo needs to be 0.20% or more. However, since Mo is an expensive element, if it is contained in excess of 2.00%, the cost becomes high, and excessive δ ferrite is generated, and the toughness is deteriorated due to generation of an embrittled phase. Therefore, Mo is 0.20 to 2.00%, preferably 0.50 to 1.70%.
Ｃｕ：０．６０〜４．００％
Ｃｕは、鋼に析出硬化粒子を生成する元素である。このためには、Ｃｕは０．６０％以上が必要である。しかし、Ｃｕは４．００％を超えて含有されると、析出硬化粒子の生成の効果が飽和し、赤熱脆性の誘起により鋼の製造性が低下する。そこで、Ｃｕは０．６０〜４．００％とし、好ましくは、１．００〜３．５０％とする。
Cu: 0.60 to 4.00%
Cu is an element that generates precipitation hardening particles in steel. For this purpose, Cu needs to be 0.60% or more. However, if Cu is contained in excess of 4.00%, the effect of forming precipitation-hardened particles is saturated, and the productivity of steel is reduced due to induction of red heat embrittlement. Therefore, Cu is set to 0.60 to 4.00%, preferably 1.00 to 3.50%.
Ｔｉ：０．５０〜３．５０％
Ｔｉは、鋼に析出硬化粒子を生成する元素である。このためには、Ｔｉは０．５０％以上が必要である。しかし、Ｔｉは３．５０％を超えて含有されると、粗大炭化物の生成による鋼の製造性が低下し、コスト高となる。そこで、Ｔｉは０．５０〜３．５０％とし、好ましくは、０．７０〜２．３０％とする。
Ti: 0.50 to 3.50%
Ti is an element that generates precipitation hardening particles in steel. For this purpose, Ti needs to be 0.50% or more. However, if Ti is contained in excess of 3.50%, the manufacturability of steel due to the formation of coarse carbides is reduced, and the cost is increased. Therefore, Ti is 0.50 to 3.50%, preferably 0.70 to 2.30%.
Ｎｂ：０．０１〜２．００％
Ｎｂは、鋼に析出硬化粒子を生成する元素である。このためには、Ｎｂは０．０１％以上が必要である。しかし、Ｎｂは２．００％を超えて含有されると、粗大炭化物の生成による鋼の製造性が低下し、コスト高となる。そこで、Ｎｂは０．０１〜２．００％とする。
Nb: 0.01 to 2.00%
Nb is an element that generates precipitation hardening particles in steel. For this purpose, Nb needs to be 0.01% or more. However, if Nb is contained in excess of 2.00%, the manufacturability of steel due to the formation of coarse carbides is lowered, and the cost is increased. Therefore, Nb is set to 0.01 to 2.00%.
Ｎ：０．０５０％以下
Ｎは、鋼の耐食性および結晶粒粗大化防止に有効な元素である。このためには、Ｎは０．０５０％以下とする必要がある。しかし、Ｎは０．０５０％を超えて含有されると、粗大炭化物の生成による鋼の製造性が低下する。そこで、Ｎは０．０５０％以下とする。
N: 0.050% or less N is an element effective for corrosion resistance of steel and prevention of grain coarsening. For this purpose, N must be 0.050% or less. However, if N is contained in an amount exceeding 0.050%, the manufacturability of steel due to the formation of coarse carbides decreases. Therefore, N is set to 0.050% or less.
［Ｃｕ］＋２．３［Ｔｉ］２．４［Ｓｉ］≧５．３・・・（１）
式（１）において、［Ｃｕ］＋２．３［Ｔｉ］２．４［Ｓｉ］が５．３以上であるとする理由は、ＣｕとＧ相が複合析出し、幅広い時効温度域で鋼に高い時効硬さが得られるからである。すなわち、最高硬さが得られる時効温度±５０℃においても、鋼の硬さは４８ＨＲＣ以上が得られる。
[Cu] +2.3 [Ti] 2.4 [Si] ≧ 5.3 (1)
In formula (1), the reason why [Cu] +2.3 [Ti] 2.4 [Si] is 5.3 or more is that the Cu and G phases precipitate together and are high in steel in a wide aging temperature range. This is because aging hardness is obtained. That is, even at an aging temperature ± 50 ° C. at which the maximum hardness is obtained, the hardness of the steel can be 48 HRC or more.
［Ｃｒ］＋３［Ｍｏ］＋［Ｎｂ］＋［Ｔｉ］＋［Ｓｉ］＋［Ｎｉ］＋［Ｃｕ］−２６（［Ｃ］＋［Ｎ］）−１０．３≧１２．０・・・（２）
式（２）において、［Ｃｒ］＋３［Ｍｏ］＋［Ｎｂ］＋［Ｔｉ］＋［Ｓｉ］＋［Ｎｉ］＋［Ｃｕ］−２６（［Ｃ］＋［Ｎ］）−１０．３が１２．０以上とする理由は、５３ＨＲＣ以上の時効硬さを確保しつつ、炭窒化物生成による鋼の耐食性の劣化を抑えることができるからである。
[Cr] +3 [Mo] + [Nb] + [Ti] + [Si] + [Ni] + [Cu] −26 ([C] + [N]) − 10.3 ≧ 12.0. 2)
In the formula (2), [Cr] +3 [Mo] + [Nb] + [Ti] + [Si] + [Ni] + [Cu] −26 ([C] + [N]) − 10.3 is 12 The reason for setting it to 0.0 or more is that deterioration of corrosion resistance of steel due to carbonitride formation can be suppressed while securing an aging hardness of 53 HRC or more.
［Ｃｒ］＋１．５［Ｓｉ］＋［Ｍｏ］＋０．５［Ｎｂ］＋２［Ｔｉ］−０．５［Ｎｉ］−６．７（［Ｃ］＋［Ｎ］）≦１９．５・・・（３）
式（３）において、［Ｃｒ］＋１．５［Ｓｉ］＋［Ｍｏ］＋０．５［Ｎｂ］＋２［Ｔｉ］−０．５［Ｎｉ］−６．７（［Ｃ］＋［Ｎ］）が１９．５以下とする理由は、時効硬さおよび耐食性を確保しつつ、δフェライト増量とマトリクスの脆化による鋼の衝撃特性の劣化を回避することができるからである。
[Cr] +1.5 [Si] + [Mo] +0.5 [Nb] +2 [Ti] −0.5 [Ni] −6.7 ([C] + [N]) ≦ 19.5. (3)
In the formula (3), [Cr] +1.5 [Si] + [Mo] +0.5 [Nb] +2 [Ti] −0.5 [Ni] −6.7 ([C] + [N]) is The reason for setting it to 19.5 or less is that it is possible to avoid deterioration of impact properties of the steel due to an increase in δ ferrite and embrittlement of the matrix while ensuring aging hardness and corrosion resistance.
次いで、発明の実施をするための形態を記載するものとする。表１に示す、Ｎｏ．１〜１６の実施例である発明例と、それらの比較例のＮｏ．１７〜３６とにおける化学成分の供試鋼を、それぞれ１００ｋｇ真空誘導加熱炉によりＶＩＭ鋼塊を溶製し、該鋼塊を１１５０℃に加熱して鍛伸により直径２０ｍｍの丸棒あるいは径１５ｍｍの角棒とした。次いでこれらの鋼材を９００〜１２００℃に加熱して１０分以上保持して固溶化熱処理し、次いで水冷により急冷して−２０℃ないし−９０℃に１０分以上保持してサブゼロ処理をして残留オーステナイトをマルテンサイトに変態させた。この後、さらに３００〜８００°Ｃに３０分以上加熱保持した後、空冷する熱処理により時効処理して、各試験片を作製した。 Next, modes for carrying out the invention shall be described. No. 1 shown in Table 1. Examples 1 to 16 of the invention and Nos. Of comparative examples thereof. Each of the test steels having chemical components 17 to 36 is melted into a VIM steel ingot by a 100 kg vacuum induction heating furnace, and the steel ingot is heated to 1150 ° C. and subjected to forging to form a round bar having a diameter of 20 mm or a diameter of 15 mm. It was a square bar. Next, these steel materials are heated to 900-1200 ° C. and held for 10 minutes or longer, followed by solution heat treatment, then rapidly cooled by water cooling, held at −20 ° C. to −90 ° C. for 10 minutes or longer, and subjected to sub-zero treatment to remain. Austenite was transformed into martensite. Thereafter, the sample was further heated and maintained at 300 to 800 ° C. for 30 minutes or more, and then subjected to an aging treatment by air-cooling heat treatment to prepare each test piece.
上記で作製した直径２０ｍｍの丸棒を使用し、熱処理による時効処理後に、鍛伸方向に垂直な断面の中周部のロックウェル硬さを測定し、表２に示すように、発明例Ｎｏ．１〜１６および比較例Ｎｏ．１７〜３６につき、時効最高硬さで、５３ＨＲＣ以上を○とし、５３ＨＲＣ未満を×として、それぞれ評価した。 Using the 20 mm diameter round bar produced above, after the aging treatment by heat treatment, the Rockwell hardness of the middle peripheral portion of the cross section perpendicular to the forging direction was measured. 1-16 and Comparative Example No. For 17 to 36, the maximum hardness of aging was evaluated by giving 53 HRC or more as ◯ and less than 53 HRC as x.
さらに、上記で作製した直径２０ｍｍの丸棒を使用し、最高硬さが得られた熱処理による時効処理温度よりも５０℃低い温度あるいは５０℃高い温度にて時効処理した後、鍛伸方向に垂直な断面の中周部のロックウェル硬さを測定し、表２に示すように、発明例Ｎｏ．１〜１６および比較例Ｎｏ．１７〜３６につき、最高硬さの時効処理温度±５０℃の範囲での硬さで、４８ＨＲＣ以上を○とし、４８ＨＲＣ未満を×として、それぞれ評価した。 Furthermore, using the 20 mm diameter round bar produced above, after aging treatment at a temperature 50 ° C. lower or 50 ° C. higher than the aging treatment temperature by the heat treatment with which the maximum hardness was obtained, it was perpendicular to the forging direction. As shown in Table 2, the No. 1 invention was measured for the Rockwell hardness at the middle circumference of the cross section. 1-16 and Comparative Example No. About 17 to 36, the hardness in the range of the aging treatment temperature of ± 50 ° C. of the highest hardness was evaluated, with 48 HRC or higher as ◯ and lower than 48 HRC as X.
さらに、上記で作製した径１５ｍｍの角棒を使用し、熱処理による時効処理した後に、鍛伸方向に平行に、径１０ｍｍで長さ５５ｍｍの角棒として２ｍｍＵノッチ試験片を作製した。この試験片を常温にてシャルピー衝撃試験に供して、表２に示すように、シャルピー衝撃値が３５Ｊ／ｃｍ2以上を○とし、３５Ｊ／ｃｍ2未満を×として評価した。 Furthermore, after using the square bar with a diameter of 15 mm produced above and performing an aging treatment by heat treatment, a 2 mm U notch test piece was produced as a square bar with a diameter of 10 mm and a length of 55 mm in parallel with the forging direction. This test piece was subjected to a Charpy impact test at room temperature, and as shown in Table 2, a Charpy impact value of 35 J / cm 2 or more was evaluated as ○, and less than 35 J / cm 2 was evaluated as ×.
上記で作製した直径２０ｍｍの丸棒から直径１２ｍｍで長さ２１ｍｍの棒状腐食試験片へ加工した後、６％塩化第２鉄の２５℃の溶液に２４時間浸漬する孔食試験を実施し、試験片の腐食度にて、表２に示すように、１０．０ｇ／ｍ2／ｈ未満のものを○、１０．０〜２０．０ｇ／ｍ2／ｈ未満のものを△、２０．０ｇ／ｍ2／ｈ以上のものを×として、孔食試験による耐食性を評価した。 After the 20 mm diameter round bar produced above was processed into a 12 mm diameter and 21 mm long rod-shaped corrosion test piece, a pitting corrosion test was conducted by immersing in a 25% solution of 6% ferric chloride for 24 hours. With respect to the degree of corrosion of the pieces, as shown in Table 2, the ones less than 10.0 g / m 2 / h are ○, the ones less than 10.0 to 20.0 g / m 2 / h are Δ, 20.0 g / h Corrosion resistance by a pitting corrosion test was evaluated with x being m 2 / h or more.
本願の化学成分の組成からなるステンレス鋼は、加工時の熱処理範囲が広く製造性に優れており、さらに、ＣｕとＧ相（Ｎｉ16Ｔｉ6Ｓｉ7）の複合析出により最高時効（ピーク時効）硬さである５３ＨＲＣ以上が得られ、さらに最高時効（ピーク時効）処理温度±５０℃の範囲における硬さで４８ＨＲＣ以上が得られ、さらにシャルピー衝撃値が３５Ｊ／ｃｍ2以上が得られ、また、さらに孔食試験で腐食度が２０．０ｇ／ｍ2／ｈ未満である優れた耐食性が得られる。 Stainless steel consisting of the composition of the chemical component of the present application has a wide heat treatment range during processing and is excellent in manufacturability, and further, maximum aging (peak aging) due to composite precipitation of Cu and G phase (Ni 16 Ti 6 Si 7 ) A hardness of 53 HRC or higher is obtained, a hardness in the range of the maximum aging (peak aging) treatment temperature ± 50 ° C. is 48 HRC or higher, and a Charpy impact value of 35 J / cm 2 or higher is obtained. Further, excellent corrosion resistance with a corrosion degree of less than 20.0 g / m 2 / h is obtained in the pitting corrosion test.
Claims (1)
［Ｃｕ］＋２．３［Ｔｉ］＋２．４［Ｓｉ］≧５．３・・・（１）
［Ｃｒ］＋３［Ｍｏ］＋［Ｎｂ］＋［Ｔｉ］＋［Ｓｉ］＋［Ｎｉ］＋［Ｃｕ］−２６（［Ｃ］＋［Ｎ］）−１０．３≧１２．０・・・（２）
［Ｃｒ］＋１．５［Ｓｉ］＋［Ｍｏ］＋０．５［Ｎｂ］＋２［Ｔｉ］−０．５［Ｎｉ］−６．７（［Ｃ］＋［Ｎ］）≦１９．５・・・（３） In 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 %: Ni: 4.0 to 9.0%, Cr: 13.0 to 22.0%, Mo: 0.20 to 2.00%, Cu: 0.60 to 4.00%, Ti: 0 .50 to 3.50%, Nb: 0.01 to 2.00%, N: 0.050% or less, comprising the balance Fe and inevitable impurities, and the following formulas (1), (2), and (3) High hardness stainless steel excellent in corrosion resistance and manufacturability characterized by satisfying the formula.
[Cu] +2.3 [Ti] +2.4 [Si] ≧ 5.3 (1)
[Cr] +3 [Mo] + [Nb] + [Ti] + [Si] + [Ni] + [Cu] −26 ([C] + [N]) − 10.3 ≧ 12.0. 2)
[Cr] +1.5 [Si] + [Mo] +0.5 [Nb] +2 [Ti] −0.5 [Ni] −6.7 ([C] + [N]) ≦ 19.5. (3)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2015206051A JP6583885B2 (en) | 2015-10-20 | 2015-10-20 | High hardness stainless steel with excellent corrosion resistance and manufacturability |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2015206051A JP6583885B2 (en) | 2015-10-20 | 2015-10-20 | High hardness stainless steel with excellent corrosion resistance and manufacturability |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2017078195A true JP2017078195A (en) | 2017-04-27 |
| JP6583885B2 JP6583885B2 (en) | 2019-10-02 |
Family
ID=58665256
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2015206051A Active JP6583885B2 (en) | 2015-10-20 | 2015-10-20 | High hardness stainless steel with excellent corrosion resistance and manufacturability |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP6583885B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2019127613A (en) * | 2018-01-23 | 2019-08-01 | 山陽特殊製鋼株式会社 | High hardness precipitation hardening stainless steel having excellent hot workability and requiring no sub-zero treatment |
| WO2021171698A1 (en) * | 2020-02-27 | 2021-09-02 | 日本冶金工業株式会社 | Precipitation-hardening martensitic stainless steel |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4415054B1 (en) * | 1966-01-06 | 1969-07-04 | ||
| JPS5471025A (en) * | 1977-11-17 | 1979-06-07 | Nippon Yakin Kogyo Co Ltd | Precipitation hardening type stainless steel with excellent corrosion resistance |
| JPH08144023A (en) * | 1994-11-16 | 1996-06-04 | Aichi Steel Works Ltd | Precipitation hardening type stainless steel excellent in strength, toughness, and corrosion resistance |
| JP2004315870A (en) * | 2003-04-15 | 2004-11-11 | Toshiba Corp | Stainless steel and structure |
| JP2005232575A (en) * | 2004-02-23 | 2005-09-02 | Mitsubishi Heavy Ind Ltd | Precipitation hardening type martensitic steel, and turbine blade using the same |
-
2015
- 2015-10-20 JP JP2015206051A patent/JP6583885B2/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4415054B1 (en) * | 1966-01-06 | 1969-07-04 | ||
| JPS5471025A (en) * | 1977-11-17 | 1979-06-07 | Nippon Yakin Kogyo Co Ltd | Precipitation hardening type stainless steel with excellent corrosion resistance |
| JPH08144023A (en) * | 1994-11-16 | 1996-06-04 | Aichi Steel Works Ltd | Precipitation hardening type stainless steel excellent in strength, toughness, and corrosion resistance |
| JP2004315870A (en) * | 2003-04-15 | 2004-11-11 | Toshiba Corp | Stainless steel and structure |
| JP2005232575A (en) * | 2004-02-23 | 2005-09-02 | Mitsubishi Heavy Ind Ltd | Precipitation hardening type martensitic steel, and turbine blade using the same |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2019127613A (en) * | 2018-01-23 | 2019-08-01 | 山陽特殊製鋼株式会社 | High hardness precipitation hardening stainless steel having excellent hot workability and requiring no sub-zero treatment |
| 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 |
Also Published As
| Publication number | Publication date |
|---|---|
| JP6583885B2 (en) | 2019-10-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR101539520B1 (en) | Duplex stainless steel sheet | |
| JP3587330B2 (en) | High hardness martensitic stainless steel with excellent pitting resistance | |
| EP3126537B1 (en) | Dual-phase stainless steel | |
| JP4645307B2 (en) | Wear-resistant steel with excellent low-temperature toughness and method for producing the same | |
| KR20150074697A (en) | Low-nickel containing stainless steels | |
| JP5291479B2 (en) | Duplex stainless steel and steel and steel products using the same | |
| JP6583885B2 (en) | High hardness stainless steel with excellent corrosion resistance and manufacturability | |
| JP4327030B2 (en) | Low Ni austenitic stainless steel with excellent overhanging and rust resistance | |
| JP2968844B2 (en) | High hardness martensitic stainless steel with excellent pitting resistance | |
| JP2018178144A (en) | Precipitation-hardened stainless steel having excellent hot workability | |
| JPH11293405A (en) | High hardness high corrosion resistance stainless steel | |
| JP3169977B2 (en) | ▲ high ▼ strength non-magnetic stainless steel | |
| JP6112065B2 (en) | Method for producing high strength 13Cr stainless steel plate with excellent toughness and workability | |
| JP6903507B2 (en) | Hot tool steel with excellent hardenability and toughness | |
| JP6501652B2 (en) | Martensitic stainless steel with excellent precipitation hardenability | |
| JP6987651B2 (en) | High hardness precipitation hardening stainless steel with excellent hot workability and no sub-zero treatment required | |
| JP2019026874A (en) | Raw material for high frequency induction hardening component | |
| JP4645306B2 (en) | Wear-resistant steel with excellent low-temperature toughness and method for producing the same | |
| JP2019501286A (en) | Lean duplex stainless steel with improved corrosion resistance and workability and method for producing the same | |
| JPH10245656A (en) | Martensitic stainless steel excellent in cold forgeability | |
| US20180363112A1 (en) | Lean duplex stainless steel and method of manufacturing the same | |
| JP6282078B2 (en) | Manufacturing method of steel parts made of mechanical structural steel with excellent grain size characteristics and impact characteristics | |
| JP2020041208A (en) | Precipitation-hardening martensitic stainless steel | |
| JP3443544B2 (en) | High strength precipitation hardening martensitic stainless steel | |
| JP2011047008A (en) | Austenitic stainless steel for spring |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20181004 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20190716 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20190828 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20190828 |
|
| R150 | Certificate of patent or registration of utility model |
Ref document number: 6583885 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |