JP2023517590A - Highly corrosion-resistant martensitic stainless steel and its manufacturing method - Google Patents
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- 230000007797 corrosion Effects 0.000 title claims abstract description 58
- 238000005260 corrosion Methods 0.000 title claims abstract description 58
- 229910001105 martensitic stainless steel Inorganic materials 0.000 title claims abstract description 47
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 19
- 239000011651 chromium Substances 0.000 claims abstract description 113
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 105
- 238000010438 heat treatment Methods 0.000 claims abstract description 76
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 36
- UFGZSIPAQKLCGR-UHFFFAOYSA-N chromium carbide Chemical compound [Cr]#C[Cr]C#[Cr] UFGZSIPAQKLCGR-UHFFFAOYSA-N 0.000 claims abstract description 26
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 26
- 229910003470 tongbaite Inorganic materials 0.000 claims abstract description 26
- 238000001556 precipitation Methods 0.000 claims abstract description 24
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 14
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 12
- 239000012535 impurity Substances 0.000 claims abstract description 11
- 238000005275 alloying Methods 0.000 claims abstract description 10
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 6
- 238000005496 tempering Methods 0.000 claims abstract description 5
- 238000005728 strengthening Methods 0.000 claims description 37
- 229910000831 Steel Inorganic materials 0.000 claims description 32
- 239000010959 steel Substances 0.000 claims description 32
- 239000000463 material Substances 0.000 claims description 28
- 238000000137 annealing Methods 0.000 claims description 23
- 229910000734 martensite Inorganic materials 0.000 claims description 16
- 229910000859 α-Fe Inorganic materials 0.000 claims description 10
- 238000001816 cooling Methods 0.000 claims description 9
- 239000011159 matrix material Substances 0.000 claims description 9
- 238000010791 quenching Methods 0.000 claims description 9
- 230000000171 quenching effect Effects 0.000 claims description 9
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 8
- 238000007710 freezing Methods 0.000 claims description 7
- 230000008014 freezing Effects 0.000 claims description 7
- 229910001220 stainless steel Inorganic materials 0.000 claims description 7
- 239000010935 stainless steel Substances 0.000 claims description 6
- CXOWYMLTGOFURZ-UHFFFAOYSA-N azanylidynechromium Chemical compound [Cr]#N CXOWYMLTGOFURZ-UHFFFAOYSA-N 0.000 claims description 5
- 238000000034 method Methods 0.000 claims description 5
- 239000007864 aqueous solution Substances 0.000 claims description 4
- 238000005336 cracking Methods 0.000 claims description 4
- 239000011780 sodium chloride Substances 0.000 claims description 4
- 229910052742 iron Inorganic materials 0.000 claims description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 abstract description 71
- 239000002436 steel type Substances 0.000 description 20
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 19
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 17
- -1 chromium carbides Chemical class 0.000 description 16
- 239000011572 manganese Substances 0.000 description 14
- 229910001566 austenite Inorganic materials 0.000 description 13
- 239000000203 mixture Substances 0.000 description 10
- 230000007423 decrease Effects 0.000 description 9
- 229910045601 alloy Inorganic materials 0.000 description 8
- 239000000956 alloy Substances 0.000 description 8
- 230000001965 increasing effect Effects 0.000 description 6
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 4
- 230000007547 defect Effects 0.000 description 4
- 238000009826 distribution Methods 0.000 description 4
- 238000005498 polishing Methods 0.000 description 4
- 238000005266 casting Methods 0.000 description 3
- 229910001873 dinitrogen Inorganic materials 0.000 description 3
- 150000001247 metal acetylides Chemical class 0.000 description 3
- 230000000717 retained effect Effects 0.000 description 3
- 238000005204 segregation Methods 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 238000005098 hot rolling Methods 0.000 description 2
- 239000002932 luster Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 206010070834 Sensitisation Diseases 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- QKCQJEFEQXXXTO-UHFFFAOYSA-N chromium;methane Chemical compound C.C.[Cr].[Cr].[Cr] QKCQJEFEQXXXTO-UHFFFAOYSA-N 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 238000007517 polishing process Methods 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000002203 pretreatment Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 230000008313 sensitization Effects 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
- 230000001131 transforming effect Effects 0.000 description 1
- 238000009827 uniform distribution Methods 0.000 description 1
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Abstract
【課題】微細なクロム炭窒化物を均一に分布させて耐食性を向上させ、強化熱処理時に適正な硬度を持つ洋食器の用途として活用できる高耐食マルテンサイト系ステンレス鋼及びその製造方法を開示する。【解決手段】本発明の一実施例において高耐食マルテンサイト系ステンレス鋼は、重量％で、Ｃ：０．１４～０．２１％、Ｎ：０．０５～０．１１％、Ｓｉ：０．１～０．６％、Ｍｎ：０．４～１．２％、Ｃｒ：１４．０～１７．０％、Ｃ＋Ｎ：０．２～０．３２％、残りのＦｅ及び不可避な不純物を含み、下記式（１）のＰＲＥＮ値が１６以上であり、クロム炭化物の析出温度が９５０℃以下であることを特徴とする。（１）Ｃｒ＋３．３Ｍｏ＋１６Ｎ（ここで、Ｃｒ、Ｍｏ、Ｎは、各合金元素の含量（重量％）を意味する）【選択図】図１A highly corrosion-resistant martensitic stainless steel that has fine chromium carbonitrides uniformly distributed to improve corrosion resistance and has appropriate hardness during tempering heat treatment and that can be used for western tableware and a method for producing the same. In one embodiment of the present invention, the highly corrosion-resistant martensitic stainless steel contains, in % by weight, C: 0.14-0.21%, N: 0.05-0.11%, Si: 0.05%. 1 to 0.6%, Mn: 0.4 to 1.2%, Cr: 14.0 to 17.0%, C + N: 0.2 to 0.32%, the remaining Fe and inevitable impurities, The PREN value of the following formula (1) is 16 or more, and the precipitation temperature of chromium carbide is 950° C. or less. (1) Cr+3.3Mo+16N (wherein Cr, Mo, and N mean the content (% by weight) of each alloying element) [selection] FIG.
Description
本発明は、高耐食マルテンサイト系ステンレス鋼及びその製造方法に係り、より詳しくは、洋食器の素材として活用できる高耐食マルテンサイト系ステンレス鋼及びその製造方法に関する。 TECHNICAL FIELD The present invention relates to a highly corrosion-resistant martensitic stainless steel and a method for producing the same, and more particularly to a highly corrosion-resistant martensitic stainless steel that can be used as a material for western tableware and a method for producing the same.
一般的に広く使用される包丁、はさみ、かみそり及び医療用器具であるメスなどの刃物用素材は、切削性及び耐摩耗性維持のために高硬度が要求され、水分と容易に接触するか、湿った雰囲気で保管されるため、優れた耐食性が要求される。このため、刃物用素材としては高硬度の高炭素マルテンサイト系ステンレス鋼が主に使用される。
刃物用素材は、高硬度を要求されるため、脆性が非常に強い。それ故、加工が容易になるように刃物用素材を一定水準以上に軟化させる必要がある。このために脆性材の熱処理作業性が容易なバッチ焼鈍（ＢＡＦ、Ｂａｔｃｈ Ａｎｎｅａｌｉｎｇ Ｆｕｒｎａｃｅ）または高温連続焼鈍工程を含んで製造することになる。
Materials for cutlery such as kitchen knives, scissors, razors, and scalpels that are widely used for medical purposes require high hardness in order to maintain cuttability and wear resistance. Excellent corrosion resistance is required because it is stored in a damp atmosphere. For this reason, high-carbon martensitic stainless steel with high hardness is mainly used as a material for cutlery.
Cutlery materials are extremely brittle because they require high hardness. Therefore, it is necessary to soften the material for cutlery to a certain level or more so as to facilitate processing. For this reason, batch annealing (BAF) or high-temperature continuous annealing processes, which facilitate heat treatment workability of brittle materials, are required for manufacturing.
焼鈍を行う間に、素材は、フェライト基地組織内に炭素とクロムが反応したクロム炭化物が微細な粒子として分散析出され、これにより基地組織内の固溶炭素の含量が低下して圧延及び酸洗のようなステンレス鋼の製造工程の適用が容易になる。それだけでなく、フェライト基地組織内に均一に分布された微細なクロム炭化物は、刃物類の最終メーカーで行われる強化熱処理工程において高温のオーステナイト相へのクロム及び炭素の速い再固溶を可能にし、急冷後のマルテンサイト組織の硬度及び耐食性を向上させることができる。
しかし、刃物用マルテンサイト系ステンレス鋼の硬度及び耐食性を向上させるために炭素及び窒素とクロムを一定量以上に含有させた場合、硬度が過度に高くなり、光沢のための研磨工程において作業性の劣位及び表面欠陥の問題を引き起こす。クロム炭化物の析出温度が高くなり、強化熱処理温度の上昇問題及びクロム炭化物の残留問題のためにむしろ耐食性に劣る虞がある。
Chromium carbide, which is a reaction between carbon and chromium, is dispersed and precipitated as fine particles in the ferrite matrix structure during annealing. It facilitates the application of stainless steel manufacturing processes such as In addition, the fine chromium carbides uniformly distributed within the ferrite matrix structure enable rapid resolution of chromium and carbon into the high-temperature austenite phase during the strengthening heat treatment process performed by the final manufacturer of cutlery, It is possible to improve the hardness and corrosion resistance of the martensite structure after quenching.
However, if carbon, nitrogen, and chromium are added to a certain amount or more in order to improve the hardness and corrosion resistance of martensitic stainless steel for cutlery, the hardness becomes excessively high, resulting in poor workability in the polishing process for luster. It causes inferiority and surface defect problems. The precipitation temperature of chromium carbide becomes high, and there is a possibility that the corrosion resistance is rather inferior due to the problem of an increase in the strengthening heat treatment temperature and the problem of residual chromium carbide.
したがって、優れた耐食性及び研磨作業に適した硬度を持つマルテンサイト系ステンレス鋼を確保するためには、微細なクロム炭化物の均一分布、及び強化熱処理温度で分解が容易になるようにクロム炭化物の析出温度を適切に制御できる鋼材の開発と焼鈍パターンの確立が要求される。 Therefore, in order to ensure a martensitic stainless steel with excellent corrosion resistance and hardness suitable for polishing operations, the uniform distribution of fine chromium carbides, and the precipitation of chromium carbides to facilitate decomposition at the strengthening heat treatment temperature. Development of steel materials that can control temperature appropriately and establishment of annealing patterns are required.
上記の問題点を解決するため、本発明は、基地組織内に微細なクロム炭窒化物を均一に分布させて耐食性を向上させ、強化熱処理時に適正な硬度を持つマルテンサイト系ステンレス熱延焼鈍鋼板、これを用いた高耐食マルテンサイト系ステンレス鋼及びその製造方法を提供することを目的にする。 In order to solve the above problems, the present invention provides a martensitic hot-rolled and annealed stainless steel sheet that has fine chromium carbonitrides uniformly distributed in the matrix structure to improve corrosion resistance and has appropriate hardness during strengthening heat treatment. , a highly corrosion-resistant martensitic stainless steel using the same and a method for producing the same.
本発明のマルテンサイト系ステンレス熱延焼鈍鋼板は、重量％で、Ｃ：０．１４～０．２１％、Ｎ：０．０５～０．１１％、Ｓｉ：０．１～０．６％、Ｍｎ：０．４～１．２％、Ｃｒ：１４．０～１７．０％、Ｃ＋Ｎ：０．２～０．３２％、残りはＦｅ及び不可避な不純物からなり、微細組織内に２５個／１００μｍ２以上のクロム炭化物またはクロム窒化物が分布し、前記クロム炭化物の析出温度が９５０℃以下であり、下記式（１）のＰＲＥＮ値が１６以上であることを特徴とする。
式（１）Ｃｒ＋３．３Ｍｏ＋１６Ｎ
（式中、Ｃｒ、Ｍｏ、Ｎは、各合金元素の含量（重量％）を意味する）
The hot-rolled and annealed martensitic stainless steel sheet of the present invention contains, in weight percent, C: 0.14 to 0.21%, N: 0.05 to 0.11%, Si: 0.1 to 0.6%, Mn: 0.4-1.2%, Cr: 14.0-17.0%, C + N: 0.2-0.32%, the rest consists of Fe and unavoidable impurities, 25 / Chromium carbide or chromium nitride having a size of 100 μm 2 or more is distributed, the precipitation temperature of the chromium carbide is 950° C. or less, and the PREN value of the following formula (1) is 16 or more.
Formula (1) Cr+3.3Mo+16N
(Wherein, Cr, Mo, and N mean the content (% by weight) of each alloying element)
本発明のマルテンサイト系ステンレス熱延焼鈍鋼板の延伸率が２０％以上であることができる。 The martensitic stainless steel hot-rolled and annealed steel sheet of the present invention may have an elongation of 20% or more.
本発明の高耐食マルテンサイト系ステンレス鋼は、重量％で、Ｃ：０．１４～０．２１％、Ｎ：０．０５～０．１１％、Ｓｉ：０．１～０．６％、Ｍｎ：０．４～１．２％、Ｃｒ：１４．０～１７．０％、Ｃ＋Ｎ：０．２～０．３２％、残りはＦｅ及び不可避な不純物からなり、下記式（１）のＰＲＥＮ値が１６以上であり、下記式（２）の値が９５０以下であることを特徴とする。
式（１）Ｃｒ＋３．３Ｍｏ＋１６Ｎ
式（２）６７４＋５６９Ｃ－４．１７Ｓｉ＋０．４６Ｍｎ＋１０．３Ｃｒ＋１９３Ｎ
（式中、Ｃｒ、Ｍｏ、Ｎ、Ｃ、Ｓｉ、Ｍｎは、各合金元素の含量（重量％）を意味する）
The highly corrosion-resistant martensitic stainless steel of the present invention has, in weight percent, C: 0.14 to 0.21%, N: 0.05 to 0.11%, Si: 0.1 to 0.6%, Mn : 0.4 to 1.2%, Cr: 14.0 to 17.0%, C + N: 0.2 to 0.32%, the rest consisting of Fe and unavoidable impurities, the PREN value of the following formula (1) is 16 or more, and the value of the following formula (2) is 950 or less.
Formula (1) Cr+3.3Mo+16N
Formula (2) 674+569C-4.17Si+0.46Mn+10.3Cr+193N
(Wherein, Cr, Mo, N, C, Si, and Mn mean the content (% by weight) of each alloying element)
本発明の高耐食マルテンサイト系ステンレス鋼は、ロックウェル硬度が４７～５３ＨＲＣの範囲であることができる。
前記ステンレス鋼は、２５℃、３．５％ＮａＣｌ水溶液下で孔食電位が１８０ｍＶ以上であることがよい。
The highly corrosion-resistant martensitic stainless steel of the present invention can have a Rockwell hardness in the range of 47 to 53 HRC.
The stainless steel preferably has a pitting potential of 180 mV or higher at 25° C. in a 3.5% NaCl aqueous solution.
本発明の高耐食マルテンサイト系ステンレス鋼の製造方法は、重量％で、Ｃ：０．１４～０．２１％、Ｎ：０．０５～０．１１％、Ｓｉ：０．１～０．６％、Ｍｎ：０．４～１．２％、Ｃｒ：１４．０～１７．０％、Ｃ＋Ｎ：０．２～０．３２％、残りはＦｅ及び不可避な不純物からなる鋳片を熱間圧延する段階、熱延材をバッチ焼鈍熱処理する段階、及び熱延焼鈍材を強化熱処理する段階を含み、前記バッチ焼鈍熱処理は、７２０～９００℃の温度範囲で５～２５時間第１の亀裂を処理する段階及び５００～７００℃の温度範囲で５～１５時間第２の亀裂を処理する段階を含み、前記熱延焼鈍材は、フェライトを基地組織として２５個／１００μｍ２以上のクロム炭化物またはクロム窒化物が分布していることを特徴とする。 In the method for producing highly corrosion-resistant martensitic stainless steel of the present invention, the weight percentages are C: 0.14 to 0.21%, N: 0.05 to 0.11%, Si: 0.1 to 0.6. %, Mn: 0.4 to 1.2%, Cr: 14.0 to 17.0%, C + N: 0.2 to 0.32%, and the balance is Fe and inevitable impurities. batch annealing heat treatment of the hot-rolled material; and strengthening heat treatment of the hot-rolled annealed material, wherein the batch annealing heat treatment treats the first crack for 5-25 hours at a temperature range of 720-900 ° C. and treating the second crack at a temperature range of 500 to 700 ° C. for 5 to 15 hours, wherein the hot rolled annealed material contains 25 pieces / 100 μm 2 or more of chromium carbide or chromium nitride with ferrite as a matrix structure Characterized by the distribution of objects.
前記バッチ焼鈍熱処理において、前記第１の亀裂を処理する段階前に４００～６００℃の温度範囲で５～１５時間の事前亀裂を処理する段階をさらに含むことがよい。
前記事前亀裂を処理する段階以後、前記第１の亀裂を処理する段階に至るまで４０～２００℃／ｈの速度で昇温することができる。
前記第１の亀裂を処理する段階以後、前記第２の亀裂を処理する段階に至るまで１０℃／ｈ以上の速度で冷却することが好ましい。
The batch annealing heat treatment may further include pre-crack treatment at a temperature range of 400-600° C. for 5-15 hours before the first crack treatment.
After the step of treating the pre-crack, the temperature can be raised at a rate of 40 to 200° C./h until the step of treating the first crack.
After the step of treating the first crack, it is preferable to cool at a rate of 10° C./h or more until the step of treating the second crack.
前記強化熱処理は、１，０００℃以上の温度で１分以上オーステナイジング処理する段階、常温で０．１５℃／ｓ以上の速度で焼入れする段階を含むことがよい。
－５０～１５０℃の温度で１０秒～５分間ディープフリージングする段階、４００～６００℃の温度で３０分～２時間焼き戻す段階をさらに含むことができる。
The strengthening heat treatment may include austenizing for 1 minute or longer at a temperature of 1,000° C. or higher, and quenching at room temperature at a rate of 0.15° C./s or higher.
The step of deep freezing at a temperature of −50 to 150° C. for 10 seconds to 5 minutes and the step of tempering at a temperature of 400 to 600° C. for 30 minutes to 2 hours may be further included.
本発明によると、本発明のマルテンサイト系ステンレス熱延焼鈍鋼板は、微細組織内の微細なクロム炭化物を均一に分布するように制御して加工性を向上させることができる。
本発明の高耐食マルテンサイト系ステンレス鋼は、炭化物析出温度の低下により強化熱処理後にクロム炭化物の残留を抑制でき、これを通じて相対的に高含量のクロム、炭素を含有しなくても優れた耐食性を示すことができる。
また、洋食器の用途に適した硬度のマルテンサイト系ステンレス鋼を提供することができる。
According to the present invention, the hot-rolled and annealed martensitic stainless steel sheet of the present invention can improve workability by controlling the fine chromium carbides in the microstructure to be uniformly distributed.
The highly corrosion-resistant martensitic stainless steel of the present invention can suppress the residual chromium carbide after the strengthening heat treatment by lowering the precipitation temperature of the carbide, thereby providing excellent corrosion resistance without containing relatively high contents of chromium and carbon. can be shown.
Also, it is possible to provide a martensitic stainless steel having a hardness suitable for use in western tableware.
本発明の一実施例によるマルテンサイト系ステンレス熱延焼鈍鋼板は、重量％で、Ｃ：０．１４～０．２１％、Ｎ：０．０５～０．１１％、Ｓｉ：０．１～０．６％、Ｍｎ：０．４～１．２％、Ｃｒ：１４．０～１７．０％、Ｃ＋Ｎ：０．２～０．３２％、残りはＦｅ及び不可避な不純物からなり、微細組織内に２５個／１００μｍ２以上のクロム炭化物またはクロム窒化物が分布し、前記クロム炭化物の析出温度が９５０℃以下であり、下記式（１）のＰＲＥＮ値（耐孔食指数）が１６以上である。
式（１）Ｃｒ＋３．３Ｍｏ＋１６Ｎ
ここで、Ｃｒ、Ｍｏ、Ｎは、各合金元素の含量（重量％）を意味する。
A martensitic stainless steel hot-rolled and annealed steel sheet according to an embodiment of the present invention contains, in weight percent, C: 0.14-0.21%, N: 0.05-0.11%, Si: 0.1-0. .6%, Mn: 0.4-1.2%, Cr: 14.0-17.0%, C + N: 0.2-0.32%, the rest consists of Fe and unavoidable impurities, in the microstructure 25 pieces/100 μm 2 or more of chromium carbides or chromium nitrides are distributed in, the precipitation temperature of the chromium carbides is 950 ° C. or less, and the PREN value (pitting corrosion resistance index) of the following formula (1) is 16 or more .
Formula (1) Cr+3.3Mo+16N
Here, Cr, Mo, and N mean the content (% by weight) of each alloying element.
以下、本発明の実施例を添付図面を参照して詳細に説明する。以下の実施例は、本発明が属する技術分野で通常の知識を持つ者に本発明の思想を十分に伝達するために提示するものである。本発明は、ここで提示した実施例に限定されず、他の形態で具体化されてもよい。図面は、本発明を明確にするために説明と関係のない部分の図示を省略し、理解を助けるために構成要素のサイズを多少誇張して表現することができる。
また、ある部分がある構成要素を「含む」とするとき、これは特に反対の記載がない限り、他の構成要素を除くのではなく、他の構成要素をさらに含んでもよいことを意味する。
単数の表現は、文脈上、明らかに例外がない限り、複数の表現を含む。
Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The following examples are presented to fully convey the spirit of the invention to those of ordinary skill in the art to which the invention pertains. The present invention is not limited to the embodiments presented herein, but may be embodied in other forms. The drawings may omit the illustration of parts irrelevant to the description in order to clarify the present invention, and may exaggerate the sizes of the components to facilitate understanding.
In addition, when a part "includes" a certain component, this does not exclude other components, unless otherwise specified, and means that it may further include other components.
Singular references include plural references unless the context clearly dictates otherwise.
刃物用、特に洋食器用マルテンサイト系ステンレス鋼は、高い耐食性と硬度が要求される。熱延焼鈍後にフェライト基地に微細なクロム炭化物及び／又はクロム窒化物（以下、クロム炭窒化物という）を均一に分布させた後、強化熱処理を通じて高温のオーステナイト相に早く再固溶させることになるが、このとき、クロム炭窒化物の再固溶が容易なため、耐食性に優れたマルテンサイト組織を確保するためには、次のような条件が要求される。 Martensitic stainless steel for cutlery, especially for western tableware, requires high corrosion resistance and hardness. After hot-rolling annealing, fine chromium carbides and/or chromium nitrides (hereinafter referred to as chromium carbonitrides) are uniformly distributed in the ferrite matrix, and then rapidly redissolved in the high-temperature austenite phase through the strengthening heat treatment. However, at this time, since chromium carbonitrides are easily redissolved, the following conditions are required in order to ensure a martensitic structure with excellent corrosion resistance.
まず、熱延焼鈍材のフェライト組織内に微細なクロム炭窒化物を形成しなければならず、次にその析出温度を低くしなければならない。従来の４２０系マルテンサイト系ステンレス鋼の場合、０．３％以上の高炭素が添加されてクロム炭窒化物の析出温度が高くなり、クロム炭窒化物の粒界優先析出及び成長に起因して局部的に粒界に粗大なクロム炭窒化物が析出し、強化熱処理時にオーステナイト相への再固溶率を下げ、硬度及び耐食性の低下をもたらす。また、０．２～０．３％の範囲の炭素が添加された場合にもクロム炭窒化物の析出温度が高くなり、強化熱処理時により高い温度で熱処理を行わなければクロム炭窒化物をすべて分解できない。このため、最終のメーカーは、強化熱処理温度を上昇させるために多くのエネルギーが必要とされてエネルギー費用が高騰するか、または熱処理炉の加熱能力が限界でクロム炭窒化物が残留することになる。クロム炭窒化物が残留すると、炭化物が腐食の基点として作用し、高含量のクロムを添加しても期待した耐食性の改善が見られない虞がある。 First, fine chromium carbonitrides must be formed in the ferrite structure of the hot-rolled annealed material, and then the precipitation temperature must be lowered. In the case of conventional 420-series martensitic stainless steel, 0.3% or more of high carbon is added to increase the precipitation temperature of chromium carbonitrides, resulting in preferential precipitation and growth of chromium carbonitrides at grain boundaries. Coarse chromium carbo-nitrides are locally precipitated at the grain boundaries, which lowers the rate of resolution into the austenite phase during the strengthening heat treatment, resulting in lower hardness and corrosion resistance. Also, when carbon is added in the range of 0.2 to 0.3%, the precipitation temperature of chromium carbonitrides increases, and all of the chromium carbonitrides are removed unless the heat treatment is performed at a higher temperature during the strengthening heat treatment. Cannot be disassembled. For this reason, the final manufacturer needs a lot of energy to raise the strengthening heat treatment temperature, resulting in a sharp increase in energy costs, or the heating capacity of the heat treatment furnace is limited, and chromium carbonitride remains. . If chromium carbonitrides remain, the carbides act as starting points for corrosion, and there is a risk that the addition of high chromium content will not provide the expected improvement in corrosion resistance.
よって、本発明は、バッチ焼鈍パターンの確立によって基地組織内に微細なクロム炭窒化物を均一に分布させるとともに、クロム炭窒化物の析出温度を強化熱処理時にすべて分解可能な水準にまで低く制御して耐食性を向上させ、強化熱処理時に適正な硬度を持つことができる高耐食マルテンサイト系ステンレス鋼の合金成分系を提供する。 Therefore, the present invention uniformly distributes fine chromium carbonitrides in the matrix structure by establishing a batch annealing pattern, and controls the precipitation temperature of the chromium carbonitrides to a level that can be completely decomposed during the strengthening heat treatment. Provided is an alloy composition system for highly corrosion-resistant martensitic stainless steel, which can improve corrosion resistance through heat treatment and can have appropriate hardness during heat treatment for strengthening.
本発明の一実施例によるマルテンサイト系ステンレス熱延焼鈍鋼板は、重量％で、Ｃ：０．１４～０．２１％、Ｎ：０．０５～０．１１％、Ｓｉ：０．１～０．６％、Ｍｎ：０．４～１．２％、Ｃｒ：１４．０～１７．０％、Ｃ＋Ｎ：０．２～０．３２％、残りはＦｅ及び不可避な不純物からなる。
以下、前記合金組成について含有量を限定した理由について具体的に説明する。下記の成分組成は、特に記載のない限り、すべて重量％を意味する。
A martensitic stainless steel hot-rolled and annealed steel sheet according to an embodiment of the present invention contains, in weight percent, C: 0.14-0.21%, N: 0.05-0.11%, Si: 0.1-0. .6%, Mn: 0.4 to 1.2%, Cr: 14.0 to 17.0%, C+N: 0.2 to 0.32%, and the balance consists of Fe and unavoidable impurities.
Hereinafter, the reasons for limiting the content of the alloy composition will be specifically described. All of the component compositions below refer to weight percent unless otherwise specified.
炭素（Ｃ）の含量は、０．１４～０．２１％である。
Ｃは、含量が低い場合、強化熱処理以降に硬度が低下して切削性及び耐摩耗性の確保が困難な場合があるので、本発明において、Ｃは、０．１４％以上添加されることがよい。ただし、Ｃ含量が過剰な場合、クロム炭窒化物が過度に形成されると、析出温度が高くなって強化熱処理後も残留することになり、耐食性が低下するだけでなく、炭素偏析により焼鈍組織内の粗大な炭化物が形成される虞がある。このため、本発明におけるＣ含量の上限は、０．２１％に制限する。より好ましくは、０．１４５～０．１７％の範囲である。
The carbon (C) content is 0.14-0.21%.
If the content of C is low, the hardness may decrease after heat treatment for strengthening, making it difficult to ensure machinability and wear resistance. good. However, if the C content is excessive, excessive chromium carbonitrides are formed, the precipitation temperature rises, and they remain even after the strengthening heat treatment, which not only deteriorates corrosion resistance, but also carbon segregation causes the annealing structure. There is a risk of formation of coarse carbides inside. Therefore, the upper limit of the C content in the present invention is limited to 0.21%. More preferably, it is in the range of 0.145-0.17%.
窒素（Ｎ）の含量は、０．０５～０．１１％である。
Ｎは、耐食性と硬度を同時に改善するために添加される元素で、Ｃの代わりに添加しても局部的な微細偏析を誘発せず、粗大な析出物を形成しないという長所がある。この効果のために本発明におけるＮは、０．０５％以上添加されることがよく、０．０８％以上がより好ましい。Ｎ含量が過剰な場合、鋳造時に溶鋼内に溶解する限度を超えることによって成分系制御が困難な場合があり、表面にピンホール欠陥が現れる虞がある。また、本発明では、洋食器用マルテンサイト系ステンレス鋼がロックウェル硬度５３ＨＲＣ超過の高硬度を要求されず、審美性のための高光沢の特性が要求されることから、Ｎ含量の上限を０．１１％に制限する。
The nitrogen (N) content is 0.05-0.11%.
N is an element added to simultaneously improve corrosion resistance and hardness, and has the advantage of not inducing local fine segregation and forming coarse precipitates when added instead of C. For this effect, N in the present invention is preferably added in an amount of 0.05% or more, more preferably 0.08% or more. If the N content is excessive, it may exceed the limit of dissolution in the molten steel during casting, which may make it difficult to control the composition system and may cause pinhole defects on the surface. Further, in the present invention, the martensitic stainless steel for western tableware does not require a high hardness exceeding 53 HRC on the Rockwell hardness, but a high gloss characteristic for aesthetics is required. Limited to 11%.
シリコン（Ｓｉ）の含量は、０．１～０．６％である。
Ｓｉは、脱酸のために必須的に添加される元素である。このため、本発明においてＳｉは、０．１％以上添加されることがよい。ただし、Ｓｉ含量が過剰な場合、酸洗性を低下させて脆性を高めるという問題がある。このため、本発明でＳｉ含量の上限は、０．６％に制限することが好ましい。
The content of silicon (Si) is 0.1-0.6%.
Si is an element that is essentially added for deoxidation. Therefore, in the present invention, Si is preferably added in an amount of 0.1% or more. However, when the Si content is excessive, there is a problem that pickling property is lowered and brittleness is increased. Therefore, in the present invention, the upper limit of Si content is preferably limited to 0.6%.
マンガン（Ｍｎ）の含量は、０．４～１．２％である。
Ｍｎは、脱酸のために必須的に添加される元素である。Ｃ及びＮ含量の低減によって減少するオーステナイト安定度の補完及びＮ固溶限の確保のために、本発明においてＭｎは、０．４％以上添加することがよい。ただし、Ｍｎ含量が過剰な場合、鋼の表面品質を低化させ、最終の熱処理材の残留オーステナイト形成により硬度を確保することが困難になる虞がある。このため、本発明においてＭｎ含量の上限は、１．２％に制限することが好ましい。より好ましくは、０．８～１．１％の範囲である。
The content of manganese (Mn) is 0.4-1.2%.
Mn is an element that is essentially added for deoxidation. In the present invention, 0.4% or more of Mn is preferably added in order to compensate for the austenite stability that decreases due to the reduction of the C and N contents and to secure the N solid solubility limit. However, if the Mn content is excessive, the surface quality of the steel may be deteriorated, and it may become difficult to ensure hardness due to the formation of retained austenite in the final heat-treated material. Therefore, the upper limit of the Mn content in the present invention is preferably limited to 1.2%. More preferably, it is in the range of 0.8-1.1%.
クロム（Ｃｒ）の含量は、１４．０～１７．０％である。
Ｃｒは、代表的なステンレス鋼の耐食性向上元素であり、Ｎ固溶の限度を高める役割を果たす。本発明では、十分な耐食性確保のためにＣｒを１４．０％以上添加する。ただし、Ｃｒ含量が過剰な場合、製造コストが上昇し、組織内のＣｒ成分の微細偏析が増加して局部的にクロム炭窒化物の粗大化を誘発させて強化熱処理された鋼材の耐食性及び硬度を低下させる問題がある。これにより、本発明においてＣｒ含量の上限は、１７．０％に制限する。好ましくは、１４．５％超過、１５．５％未満の範囲である。
The content of chromium (Cr) is 14.0-17.0%.
Cr is a representative element for improving the corrosion resistance of stainless steel, and plays a role of increasing the limit of N solid solution. In the present invention, 14.0% or more of Cr is added to ensure sufficient corrosion resistance. However, if the Cr content is excessive, the manufacturing cost increases and the fine segregation of the Cr component in the structure increases, causing local coarsening of chromium carbonitrides. There is a problem of lowering Accordingly, the upper limit of the Cr content is limited to 17.0% in the present invention. Preferably, the range is greater than 14.5% and less than 15.5%.
炭素（Ｃ）及び窒素（Ｎ）含量の合計は、０．２～０．３２％である。
Ｃ、Ｎは、強化熱処理後、鋼の硬度を確保するために０．２％以上添加することがよく、炭窒化物の個数の確保のためには、０．２３％以上が好ましい。一方、Ｃ＋Ｎ含量が過剰な場合、熱延鋼板のバッチ焼鈍時に分布するクロム炭窒化物の分率が増加して延伸率が低下する虞があり、本発明においてＣ＋Ｎ含量の上限は、０．３２％に制限する。また、洋食器の用途のマルテンサイト系ステンレス鋼の場合、一般刃物用途に対してのＨＲＣ５３を超過する高硬度は要求されず、審美性を備えるための高光沢特性が要求される。このような高光沢洋食器の製造時、強化熱処理後の硬度がＨＲＣ５３を超えると、光沢を出すための研磨作業の作業性が低下した上に、表面に波状などの表面欠陥を誘発して生産性が低下するという問題点が発生する。したがって、過度な高硬度化を防止し、適正な硬度範囲に制御するためにＣ＋Ｎ含量の上限を０．２８％以下に制限する。
The total carbon (C) and nitrogen (N) content is 0.2-0.32%.
C and N are preferably added in an amount of 0.2% or more in order to secure the hardness of the steel after heat treatment for strengthening, and preferably 0.23% or more in order to secure the number of carbonitrides. On the other hand, if the C+N content is excessive, the fraction of chromium carbonitrides distributed during batch annealing of the hot-rolled steel sheet may increase and the elongation ratio may decrease. %. In the case of martensitic stainless steel for Western tableware, high hardness exceeding HRC 53 for general cutlery is not required, and high gloss characteristics are required for providing aesthetics. When manufacturing such high-gloss tableware, if the hardness after the strengthening heat treatment exceeds HRC 53, the workability of the polishing work for producing gloss is lowered, and surface defects such as waves are induced on the surface. A problem arises that the performance is lowered. Therefore, the upper limit of the C+N content is limited to 0.28% or less in order to prevent an excessive increase in hardness and control the hardness within an appropriate range.
本発明の残り成分は、鉄（Ｆｅ）である。ただし、通常の製造過程では原料または周囲環境から意図されない不純物が不可避に混入することがあり、これを排除することはできない。前記不純物は、通常の製造過程の技術者であれば誰でも分かるものであるため、そのすべての内容を特に本明細書では言及しない。
また、各合金元素の含量を上述の条件に限定する以外にも、これらの関係を次のようにさらに限定してもよい。
The remaining component of the present invention is iron (Fe). However, unintended impurities from raw materials or the surrounding environment may inevitably be mixed in during normal manufacturing processes, and this cannot be eliminated. Since the impurities are known to anyone skilled in the normal manufacturing process, the full content thereof is not specifically mentioned herein.
In addition to limiting the content of each alloying element to the conditions described above, these relationships may be further limited as follows.
本発明のマルテンサイト系ステンレス熱延焼鈍鋼板と強化熱処理されたマルテンサイト系ステンレス鋼は、下記式（１）で示す耐孔食指数（Ｐｉｔｔｉｎｇ Ｒｅｓｉｓｔａｎｃ Ｅｅｑｕｉｖａｌｅｎｔ Ｎｕｍｂｅｒ：ＰＲＥＮ、）値が１６以上である。
式（１）Ｃｒ＋３．３Ｍｏ＋１６Ｎ
合金元素の含量を上述の条件に限定する以外にも、式（１）の値を１６．５以上になるように各合金元素の含量を制御することにより、優れた耐食性を確保できる。
The hot-rolled and annealed martensitic stainless steel sheet and martensitic stainless steel subjected to strengthening heat treatment of the present invention have a Pitting Resistance Equivalent Number (PREN) value of 16 or more, as shown by the following formula (1).
Formula (1) Cr+3.3Mo+16N
In addition to limiting the content of the alloying elements to the conditions described above, excellent corrosion resistance can be ensured by controlling the content of each alloying element so that the value of formula (1) is 16.5 or more.
強化熱処理前にクロム炭窒化物が微細に分布されたマルテンサイト系ステンレス熱延焼鈍鋼板の製造方法を説明する。
上記の合金組成を持つマルテンサイト系ステンレス熱延材は、連続鋳造または鋼塊鋳造によって鋳片として作製された後、熱間圧延して加工処理が可能な熱延鋼板として製造される。以後、製造された熱延鋼板は、刃物用として使用可能な厚さで精密圧延のような加工を行う前に良好な加工性の確保のためにバッチ焼鈍熱処理を行う。バッチ焼鈍熱処理後の微細組織は、フェライトを主組織とし、微細なクロム炭化物が均一に分布されることがよい。マルテンサイト系ステンレス熱延焼鈍材は、後続する強化熱処理段階によってマルテンサイト系ステンレス鋼として製造される。
A method for manufacturing a martensitic stainless hot-rolled and annealed steel sheet in which chromium carbonitrides are finely distributed before the strengthening heat treatment will be described.
The hot-rolled martensitic stainless steel having the above alloy composition is produced as a slab by continuous casting or ingot casting, and then hot-rolled to produce a hot-rolled steel sheet that can be processed. Thereafter, the manufactured hot-rolled steel sheet is subjected to a batch annealing heat treatment to ensure good workability before being processed such as precision rolling so as to have a thickness that can be used for cutlery. The fine structure after the batch annealing heat treatment is preferably composed of ferrite as a main structure, and fine chromium carbides are uniformly distributed. A martensitic stainless hot-rolled and annealed material is produced as a martensitic stainless steel by a subsequent strengthening heat treatment step.
まず、バッチ焼鈍熱処理について説明する。
バッチ焼鈍熱処理は、第１の亀裂を処理する段階、第２の亀裂を処理する段階を含む。また、選択的に第１の亀裂を処理する段階前に事前亀裂を処理する段階をさらに含んでもよい。
事前亀裂を処理する段階は、第１の亀裂段階前に亀裂を処理する段階で、素材の全般にわたって温度の均一な上昇のための前処理段階である。一例によれば、事前亀裂を処理する段階は、４００～６００℃の温度範囲で５～１０時間一定温度で加熱することが好ましい。
加熱温度が４００℃未満であるか、または６００℃を超えると、素材の全般にわたって温度を均一に上昇させることができない。また、加熱時間が５時間未満であるか、または１０時間を超えると、素材の全般にわたって温度を均一に上昇させることができない。
First, the batch annealing heat treatment will be explained.
A batch annealing heat treatment includes treating a first crack and treating a second crack. Alternatively, the method may further include treating the pre-crack prior to treating the first crack.
The pre-crack treatment stage is a pre-treatment stage for a uniform increase in temperature throughout the material, which is a crack treatment stage prior to the first crack stage. According to one example, the step of treating the pre-cracks preferably includes heating at a constant temperature in the temperature range of 400-600° C. for 5-10 hours.
If the heating temperature is less than 400°C or exceeds 600°C, the temperature cannot be raised uniformly over the entire material. Moreover, if the heating time is less than 5 hours or exceeds 10 hours, the temperature cannot be raised uniformly over the entire material.
第１の亀裂を処理する段階は、熱延鋼板の微細組織内にクロム炭窒化物を均一に分布させる段階である。一例によれば、第１の亀裂を処理する段階は、７２０～９００℃で５～２５時間一定温度で加熱することが好ましい。
加熱温度が７２０℃未満の場合、結晶粒界に局部的なクロム炭窒化物凝集部が形成され、一方、加熱温度が９００℃を超えると、結晶粒界に粗大なクロム炭窒化物が形成される。
また、加熱時間が５時間未満の場合、クロム炭窒化物のサイズを微細化できるが、一部分にクロム炭窒化物が集中分布され、逆に、加熱時間が２５時間を超えると、互いに近接したクロム炭窒化物が混合されて局部的に粗大に形成されてもよい。
凝集されるか、または粗大に形成されたクロム炭化物は、材質の不均衡をもたらして延性が低下し、最終製品の剛性、延性、耐食性が低下する虞がある。これを防止するために本発明は、第１の亀裂を処理する段階において加熱温度は、７２０～９００℃、加熱時間は、５～２５時間に限定する。
The first crack-treating step is to uniformly distribute chromium carbonitrides within the microstructure of the hot-rolled steel. According to one example, the step of treating the first crack is preferably constant temperature heating at 720-900° C. for 5-25 hours.
When the heating temperature is less than 720°C, local chromium carbonitride aggregates are formed at the grain boundaries, while when the heating temperature exceeds 900°C, coarse chromium carbonitrides are formed at the grain boundaries. be.
In addition, when the heating time is less than 5 hours, the size of the chromium carbonitrides can be reduced, but the chromium carbonitrides are concentrated and distributed in one part. Carbonitrides may be mixed and locally coarsened.
Agglomerated or coarsely formed chromium carbides can lead to material imbalances that reduce ductility and reduce the stiffness, ductility and corrosion resistance of the final product. In order to prevent this, the present invention limits the heating temperature to 720 to 900° C. and the heating time to 5 to 25 hours in the step of treating the first crack.
第２の亀裂を処理する段階は、クロム炭窒化物を球状化する段階である。クロム炭窒化物を球状化させることにより、後続する加工工程における加工性を向上させることができるようになる。一例によれば、第２の亀裂を処理する段階は、５００～７００℃の温度範囲で５～１５時間一定温度で加熱することが好ましい。 The second crack treating step is to spheroidize the chromium carbonitride. By spheroidizing the chromium carbonitride, it becomes possible to improve the workability in subsequent processing steps. According to one example, the step of treating the second crack is preferably heating at a constant temperature in the temperature range of 500-700° C. for 5-15 hours.
クロム炭窒化物が球状化されるためには、少なくとも５００℃以上の加熱温度が必要である。一方、その加熱温度が７００℃を超えると、球状化されたクロム炭窒化物が過度に成長し、個数が減少して延性が低下する。また、加熱時間が５時間未満の場合、クロム炭窒化物が球状化されず、加熱時間が１５時間を超えると、クロム炭窒化物が過度に成長して延性が低下する。 A heating temperature of at least 500° C. or higher is required to spheroidize the chromium carbonitride. On the other hand, if the heating temperature exceeds 700° C., spheroidized chromium carbonitrides grow excessively, the number decreases, and the ductility decreases. If the heating time is less than 5 hours, the chromium carbonitrides are not spheroidized, and if the heating time exceeds 15 hours, the chromium carbonitrides grow excessively and the ductility decreases.
事前亀裂を処理する段階以後、第１の亀裂を処理する段階に至るまで、４０～２００℃／ｈの速度で昇温させることができる。
昇温速度が４０℃／ｈ未満の場合にはクロム炭窒化物が粗大になる温度区間である７００～７５０℃を経由する時間が増加することがあり、これによりクロム炭窒化物のサイズが粗大になって微細組織内に分布するクロム炭化物の個数が減少して延性が低下する虞がある。一方、昇温速度が２００℃／ｈを超えると、クロム炭窒化物が粗大化される温度区間を経由する時間が減少し、微細なクロム炭窒化物を確保できる。しかし、クロム炭窒化物が拡散する時間が不足して不均一に分布されるという短所がある。
第１の亀裂を処理する段階以後、第２の亀裂を処理する段階に至るまで１０℃／ｈ以上の速度で冷却させることができる。
冷却速度が１０℃／ｈ未満であると、クロム炭窒化物が粗大化される温度区間を経由する時間が増加し、これにより、微細組織内におけるクロム炭窒化物が粗大化して高耐食及び高硬度を確保しにくくなる。
第２の亀裂を処理する段階以後は、空冷できる。
After the stage of treating the pre-crack, the temperature can be increased at a rate of 40-200° C./h until the stage of treating the first crack.
If the heating rate is less than 40° C./h, the time required to pass through the temperature range of 700 to 750° C. where chromium carbonitrides become coarse may increase, and as a result, the size of chromium carbonitrides becomes coarse. As a result, the number of chromium carbides distributed in the microstructure decreases, and there is a risk that the ductility will decrease. On the other hand, when the heating rate exceeds 200° C./h, the time required to pass through the temperature section where chromium carbonitrides are coarsened is reduced, and fine chromium carbonitrides can be obtained. However, there is a disadvantage that the chromium carbonitrides do not have enough time to diffuse and are unevenly distributed.
After the step of treating the first crack, it can be cooled at a rate of 10° C./h or more until the step of treating the second crack.
If the cooling rate is less than 10 ° C./h, the time required to pass through the temperature interval where chromium carbonitrides are coarsened increases, and as a result, the chromium carbonitrides in the microstructure coarsen, resulting in high corrosion resistance and high corrosion resistance. It becomes difficult to secure hardness.
Air cooling is allowed after the second crack treatment step.
上記のバッチ焼鈍熱処理する段階において、微細組織内の炭素とクロムが反応してクロム炭化物を形成し、窒素もクロムと反応してクロム窒化物を形成する。その結果、組織内に固溶された炭素含量が減少して加工性が向上し、後続するステンレス鋼の製造工程が容易になり、目的とする最終形状に加工できる。本発明の一実施例によるマルテンサイト系ステンレス熱延焼鈍鋼板は、延伸率が２０％以上であることがよい。クロム窒化物も強化熱処理を通じて急冷後、マルテンサイト組織の硬度及び耐食性を向上させる。
また、上記のバッチ焼鈍熱処理段階で微細組織内に均一で微細に分布されたクロム炭窒化物は、後続する強化熱処理段階で高温のオーステナイト相への炭素、窒素及びクロムの速い再固溶を可能にし、急冷後のマルテンサイト組織の硬度及び耐食性を向上させることができる。
During the above batch annealing heat treatment step, carbon and chromium in the microstructure react to form chromium carbides, and nitrogen also reacts with chromium to form chromium nitrides. As a result, the carbon content dissolved in the structure is reduced, the workability is improved, the subsequent manufacturing process of the stainless steel is facilitated, and the desired final shape can be obtained. The hot-rolled and annealed martensitic stainless steel sheet according to an embodiment of the present invention may have an elongation of 20% or more. Chromium nitride also improves the hardness and corrosion resistance of the martensite structure after quenching through strengthening heat treatment.
In addition, the chromium carbonitrides uniformly and finely distributed in the microstructure in the batch annealing heat treatment step enable rapid resolution of carbon, nitrogen, and chromium into the high-temperature austenite phase in the subsequent strengthening heat treatment step. It is possible to improve the hardness and corrosion resistance of the martensite structure after quenching.
本発明によれば、上記のバッチ焼鈍熱処理を通じてマルテンサイト系ステンレス熱延焼鈍鋼板の微細組織内のクロム炭窒化物を微細化し、均一に分布させることができ、微細組織内に２５個／１００μｍ２以上のクロム炭窒化物が分布される。微細組織内に２５個／１００μｍ２未満でクロム炭窒化物が分布された場合、クロム炭窒化物の個数は少なく、サイズは粗大であるので、延性が低下し、後続する強化熱処理段階でクロム及び炭素の再固溶が難しく、目的とする硬度を確保できない。 According to the present invention, the chromium carbonitrides in the microstructure of the martensitic stainless steel hot-rolled and annealed steel sheet can be refined and uniformly distributed through the batch annealing heat treatment, and 25/100 μm 2 in the microstructure. The above chromium carbonitrides are distributed. When the chromium carbonitrides are distributed in the microstructure at less than 25/100 μm 2 , the chromium carbonitrides are few in number and coarse in size, resulting in reduced ductility and subsequent strengthening heat treatment steps to reduce chromium and Re-solution of carbon is difficult, and the intended hardness cannot be secured.
本発明によれば、バッチ焼鈍熱処理されたマルテンサイト系ステンレス熱延焼鈍材は、最終形状に加工された後に強化熱処理する段階を経てマルテンサイト系ステンレス鋼として製造できる。
強化熱処理は、オーステナイジング処理する段階、焼入れする段階を含んでもよく、必要に応じてディープフリージング（ｄｅｅｐ ｆｒｅｅｚｉｎｇ）する段階、焼き戻す段階をさらに含んでもよい。
According to the present invention, the batch-annealed hot-rolled martensitic stainless steel material can be manufactured as a martensitic stainless steel through a strengthening heat treatment after being processed into a final shape.
The strengthening heat treatment may include an austenizing step, a quenching step, and, if necessary, a deep freezing step and a tempering step.
オーステナイジング処理する段階は、鋼材の基地組織をフェライトからオーステナイトに変態させる段階である。
当該段階でクロム炭窒化物がクロムと炭素、窒素の形態で基地組織として再固溶されて後続する焼入れまたはディープフリージング段階以後、マルテンサイトステンレス鋼の硬度を高めることができる。
The austenizing step is a step of transforming the base structure of the steel material from ferrite to austenite.
In this step, the chromium carbonitride is redissolved as a matrix structure in the form of chromium, carbon, and nitrogen, so that the hardness of the martensitic stainless steel can be increased after the subsequent quenching or deep freezing step.
一例によれば、オーステナイジング処理する段階は、１，０００℃以上の温度で１分以上熱処理できる。ここで、クロム炭化物（Ｃｒ２３Ｃ６）の析出温度によってオーステナイジング時のクロムと炭素をすべて再固溶できるが、本発明が目的とするクロム炭化物の析出温度は、９５０℃以下である。クロム炭化物の析出温度は、合金成分の組成によって変化させることができ、下式（２）で表すことができる。式（２）から分かるように、特にクロムと炭素含量が高いほどクロム炭化物の析出温度が高くなる。
式（２）６７４＋５６９Ｃ－４．１７Ｓｉ＋０．４６Ｍｎ＋１０．３Ｃｒ＋１９３Ｎ
According to an example, the austenizing step may include heat treatment at a temperature of 1,000° C. or higher for 1 minute or longer. Here, chromium and carbon during austenizing can all redissolve according to the precipitation temperature of chromium carbide (Cr 23 C 6 ). The precipitation temperature of chromium carbide can be changed depending on the composition of the alloy components, and can be expressed by the following formula (2). As can be seen from equation (2), the higher the chromium and carbon contents, the higher the precipitation temperature of the chromium carbide.
Formula (2) 674+569C-4.17Si+0.46Mn+10.3Cr+193N
耐食性向上のためにクロムを多量に含有するか、または硬度向上のために炭素及び窒素を多量に含有する場合、クロム炭化物の析出温度が高くなり強化熱処理のオーステナイジング温度範囲に制約が伴うことになる。上記のように、実際の強化熱処理時に加熱能力の限界による設備問題やエネルギーコストの増加問題によりクロム炭化物がすべて再固溶されずに残留した場合、むしろ耐食性が低下する。したがって、本発明では、合金組成とともに、クロム炭化物の析出温度を９５０℃以下に制限し、添加されたクロム及び炭素の全量が耐食性に寄与するようにする。 When a large amount of chromium is contained to improve corrosion resistance, or a large amount of carbon and nitrogen is contained to improve hardness, the precipitation temperature of chromium carbide rises and the austenizing temperature range of the strengthening heat treatment is restricted. Become. As described above, if all the chromium carbide remains without being redissolved due to the equipment problem due to the limit of heating capacity and the problem of increased energy cost during the actual strengthening heat treatment, the corrosion resistance rather deteriorates. Therefore, in the present invention, along with the alloy composition, the precipitation temperature of chromium carbide is limited to 950° C. or less so that the total amount of added chromium and carbon contributes to corrosion resistance.
オーステナイジング処理温度が１，０００℃未満の場合、クロム炭化物をすべて分解することが難しくなり、処理時間が長くなり経済的でない。一方、処理温度が高すぎると、エネルギーコストが上昇して非経済的であり、炭化物の再固溶量の増加による残留オーステナイトの過多形成により硬度が低下する虞があり、結晶粒が過度に成長するため、１，２００℃以下に制限することが好ましい。
また、オーステナイジング処理時間が１分未満の場合、クロム炭化物をすべて分解することが困難であり、目的とする硬度を確保できず、処理時間が長くなる場合、結晶粒が過度に成長して残留オーステナイトが発生する虞があるため、３０分以下に制限することが好ましい。
If the austenizing temperature is less than 1,000° C., it becomes difficult to decompose all the chromium carbides, and the treatment takes a long time, which is not economical. On the other hand, if the treatment temperature is too high, the energy cost will increase, which is uneconomical, and there is a risk that the hardness will decrease due to excessive formation of retained austenite due to an increase in the amount of re-solution of carbide, and crystal grains will grow excessively. Therefore, it is preferable to limit the temperature to 1,200° C. or less.
In addition, if the austenizing treatment time is less than 1 minute, it is difficult to decompose all the chromium carbide, and the desired hardness cannot be secured. Since austenite may be generated, it is preferable to limit the time to 30 minutes or less.
焼入れする段階は、オーステナイジング処理以後に０．１５℃／ｓ以上の冷却速度で常温まで急速冷却してオーステナイト組織を硬度の高いマルテンサイトに変態させる段階である。０．２℃／ｓ以上の冷却速度で冷却すると、より高いマルテンサイト硬度が得られる。
ディープフリージングする段階は、常温で焼入れした鋼材を極低温でさらに冷却して残留オーステナイト組織をマルテンサイト組織にさらに変態させる段階であり、該当段階で鋼材の硬度がさらに上昇することになる。一例によれば、ディープフリージングする段階は、－５０～－１５０℃の温度で１０秒～５分間氷点下（ｓｕｂｚｅｒｏ）の熱処理を行ってもよい。
The quenching step is a step of rapidly cooling to room temperature at a cooling rate of 0.15° C./s or more after the austenizing treatment to transform the austenite structure into martensite having a high hardness. Higher martensite hardness can be obtained by cooling at a cooling rate of 0.2° C./s or more.
Deep freezing is a step in which the steel quenched at room temperature is further cooled at an extremely low temperature to further transform the retained austenite structure into a martensite structure, and the hardness of the steel is further increased at this step. According to one example, the step of deep freezing may include a subzero heat treatment at a temperature of -50 to -150°C for 10 seconds to 5 minutes.
焼き戻す段階は、ディープフリージングする段階以降、硬度が高く、脆性の強いマルテンサイト組織に靭性を与えるための段階である。一例によれば、４００～６００℃の温度で３０分～２時間熱処理できる。 The tempering step is a step for imparting toughness to the martensitic structure having high hardness and high brittleness after the deep freezing step. According to one example, the heat treatment can be performed at a temperature of 400-600° C. for 30 minutes to 2 hours.
本発明によれば、上記の強化熱処理する段階でフェライト組織をマルテンサイト組織に最終変態させることがあり、目的とする硬度及び高耐食の特性を確保できる。例えば、強化熱処理によって再固溶させた後、素材の断面に残留するクロム炭窒化物の面積分率は、２％以下であることがよい。
本発明の一実施例による高耐食マルテンサイト系ステンレス鋼は、２５℃、３．５％ＮａＣｌ水溶液下で、孔食電位が１８０ｍＶ以上であることがよい。これは上記の式（１）のＰＲＥＮ値を１６．０以上及びクロム炭化物の析出温度を９５０℃以下に制御して炭化物をすべて再固溶することにより確保できる。
また、本発明の一実施例による高耐食マルテンサイト系ステンレス鋼は、ロックウェル硬度が４７～５３ＨＲＣであることがよい。
According to the present invention, the ferrite structure may be finally transformed into the martensite structure in the step of the strengthening heat treatment, and the intended hardness and high corrosion resistance properties can be ensured. For example, it is preferable that the area fraction of chromium carbonitride remaining in the cross section of the material is 2% or less after being redissolved by the strengthening heat treatment.
The highly corrosion-resistant martensitic stainless steel according to an embodiment of the present invention preferably has a pitting potential of 180 mV or more at 25° C. in a 3.5% NaCl aqueous solution. This can be ensured by controlling the PREN value of the above formula (1) to 16.0 or more and the precipitation temperature of chromium carbide to 950° C. or less to redissolve all the carbides.
Also, the highly corrosion-resistant martensitic stainless steel according to an embodiment of the present invention preferably has a Rockwell hardness of 47 to 53 HRC.
刃物用マルテンサイト系ステンレス鋼の中で洋食器用途の場合、高い硬度が要求されず、光沢のための研磨においても作業生産性の問題が発生することがあり、５３ＨＲＣ超過の高硬度は要求されない。洋食器のナイフ基準で刃部位は、４９～５３ＨＲＣ、取っ手部位は、４７～５１ＨＲＣの硬度範囲が適している。したがって、本発明では、Ｃ＋Ｎ含量の上限を０．３２％以下に制限し、クロム炭化物の析出温度の制御を通じて全量が再固溶されても適正硬度を持つように合金成分系を上述の範囲に制限する。これによる本発明の高耐食マルテンサイト系ステンレス鋼は、４７～５３ＨＲＣのロックウェル硬度範囲を有することがよい。 Among the martensitic stainless steels for cutlery, high hardness over 53HRC is not required for Western tableware applications, and problems with work productivity may occur even in polishing for luster. . A hardness range of 49 to 53 HRC for the blade portion and 47 to 51 HRC for the handle portion is suitable for Western tableware knives. Therefore, in the present invention, the upper limit of the C + N content is limited to 0.32% or less, and the alloy composition is set within the above range so that the proper hardness is maintained even if the entire amount is redissolved by controlling the precipitation temperature of the chromium carbide. Restrict. Accordingly, the highly corrosion-resistant martensitic stainless steel of the present invention preferably has a Rockwell hardness range of 47 to 53 HRC.
以下、本発明の好ましい実施例を通じて、より詳細に説明する。
〔実施例〕
下記表１に記載した合金成分系で鋳造して熱間圧延した後、バッチ焼鈍熱処理した。バッチ焼鈍は、５００℃で７時間事前亀裂を処理し、約１００℃／ｈ速度で昇温して８４０℃で１０時間第１の亀裂を処理し、１５℃／ｈの速度で冷却して５８０℃で１０時間維持した後、空冷した。
Hereinafter, the preferred embodiments of the present invention will be described in more detail.
〔Example〕
After casting with the alloy composition system shown in Table 1 below and hot rolling, batch annealing heat treatment was performed. Batch annealing was 500° C. for 7 hours pre-cracking, ramping at about 100° C./h rate to 840° C. for 10 hours first cracking, cooling at 15° C./h rate to 580 C. for 10 hours and then air-cooled.
表１において、クロム炭窒化物の析出温度（℃）と素材の表面に窒素ガスによるピンホール（ｐｉｎ ｈｏｌｅ）発生の有無を○、×で示した。
鋼種Ｂは、本発明の範囲を外れる多量のＮが添加されて表面にピンホールが発生し、鋼種Ｅは、Ｎ含量が適正であるにもかかわらず、窒素固溶度に影響を及ぼすＣｒの含量が低く、オーステナイト安定化元素であるＣとＭｎの含量も相対的に低く、固溶限を超えたＮがガスとして発生してピンホールが発生した。本発明の合金組成範囲で該当する鋼種Ｆは、窒素ガスによるピンホールが発生せず、クロム炭化物の析出温度も９３７℃と低く、後述する強化熱処理時に有利に作用した。
In Table 1, the deposition temperature (° C.) of chromium carbonitride and the presence or absence of pinhole formation due to nitrogen gas on the surface of the material are indicated by ◯ and ×.
Steel type B has pinholes on the surface due to the addition of a large amount of N outside the scope of the present invention. The content of C and Mn, which are austenite stabilizing elements, is low, and the content of C and Mn, which are elements that stabilize austenite, is relatively low, and N exceeding the solid solubility limit is generated as gas, resulting in pinholes. Steel type F, which falls within the alloy composition range of the present invention, did not generate pinholes due to nitrogen gas, and had a low chromium carbide precipitation temperature of 937°C, which worked favorably during the strengthening heat treatment described later.
また、ＣとＣｒの含量が高い場合、クロム炭化物の析出温度は、９９０℃以上を示すが、ＣとＣｒを含む全体の合金組成範囲が本発明の範囲に属する場合には、析出温度が９５０℃以下であることが確認できた。
前記のように製造されたＡ～Ｆ熱延焼鈍材について走査型電子顕微鏡（ＳＥＭ）で微細組織内のクロム炭窒化物の個数を観察し、ＪＩＳ１３Ｂ規格で引張試験を行って得られた延伸率を下記表２に示した。
In addition, when the contents of C and Cr are high, the precipitation temperature of chromium carbide is 990° C. or higher. °C or less.
The number of chromium carbonitrides in the microstructure of the A to F hot-rolled and annealed materials manufactured as described above was observed with a scanning electron microscope (SEM), and the elongation ratio obtained by performing a tensile test according to the JIS13B standard. are shown in Table 2 below.
表２を参照すると、鋼種Ａは、０．６％以上のＣを含んでクロム炭窒化物が６０個／１００μｍ２以上で多量観察されたが、延伸率が１７．６％で極めて劣位であることが分かった。
鋼種ＢとＣは、共にＣ含量が約０．２５％と高いが、Ｎ含量に差異がある。鋼種Ｂは、Ｃ＋Ｎ含量がさらに高いにもかかわらず、鋼種Ｃより少ない２１個／１００μｍ２の炭窒化物の個数を示したが、これは析出されたクロム炭窒化物の分布分率が高すぎ、粗大化されたものと推定される。また、鋼種Ｂは、Ｃ＋Ｎ含量が高く、延伸率が１９．６％でやや劣位であることが分かった。鋼種Ｃは、クロム炭窒化物の分布個数が３２個／１００μｍ２、及び延伸率が２９．３％で良好であるが、クロム炭化物の析出温度が９９１℃と高く、強化熱処理後にクロム炭窒化物が残留している可能性が高い。
鋼種ＤとＥの場合、延伸率は、２８％以上で良好と測定されたが、クロム炭窒化物の個数が２５個／１００μｍ２未満水準で少なく観察された。これはＣ＋Ｎ含量は適正であるが、Ｃｒ含量が低いためであると推定された。
Referring to Table 2, steel type A contains 0.6% or more of C and a large amount of chromium carbonitrides is observed at 60 pieces/100 μm 2 or more, but the elongation is 17.6%, which is extremely inferior. I found out.
Steel grades B and C both have a high C content of about 0.25%, but differ in N content. Steel type B showed a lower number of carbonitrides than steel type C, 21/100 μm 2 , despite the higher C+N content, which was due to the distribution fraction of precipitated chromium carbonitrides being too high. , which is assumed to be coarsened. In addition, steel type B has a high C+N content and an elongation ratio of 19.6%, which is slightly inferior. Steel type C has a good distribution number of chromium carbonitrides of 32 pieces/100 μm 2 and an elongation ratio of 29.3%. is likely to remain.
In the case of steel types D and E, the elongation ratio was measured to be good at 28% or more, but the number of chromium carbonitrides was observed to be less than 25/100 μm 2 . It was presumed that this was because the Cr content was low although the C+N content was appropriate.
図１は、鋼種Ｆ熱延焼鈍鋼板の微細組織のクロム炭窒化物を観察した走査電子顕微鏡（ＳＥＭ）写真である。本発明の発明鋼に該当する鋼種Ｆ熱延焼鈍材は、フェライト基地組織に微細なクロム炭窒化物が均一に分布していることが確認でき、表２のように３０個／１００μｍ２水準のクロム炭窒化物の分布を示し、延伸率も３０．２％と優れていると測定された。 FIG. 1 is a scanning electron microscope (SEM) photograph of chromium carbonitrides in the microstructure of a steel type F hot-rolled and annealed steel sheet. In the steel type F hot-rolled annealed material, which corresponds to the invention steel of the present invention, it can be confirmed that fine chromium carbonitrides are uniformly distributed in the ferrite matrix structure. The distribution of chromium carbonitride was shown, and the elongation ratio was also measured to be excellent at 30.2%.
以後、マルテンサイト系ステンレス熱延焼鈍材を１，０５０℃オーステナイジング、０．２７℃／ｓの冷却速度で焼入れしてマルテンサイト鋼として製造した。下記表３には、耐食性判断のためにＰＲＥＮと孔食電位測定値を示し、硬度判断のためにロックウェル硬度を測定して示した。ＰＲＥＮ値は、式（１）に各合金元素の含量（重量％）を代入して導き出し、孔食電位は、２５℃、３．５％ＮａＣｌ水溶液下で測定した。 After that, the hot-rolled and annealed martensitic stainless steel was austenized at 1,050° C. and quenched at a cooling rate of 0.27° C./s to produce martensitic steel. Table 3 below shows measured values of PREN and pitting potential for judging corrosion resistance, and measured Rockwell hardness for judging hardness. The PREN value was derived by substituting the content (% by weight) of each alloying element into formula (1), and the pitting potential was measured at 25° C. under a 3.5% NaCl aqueous solution.
０．６％以上の高炭素を含有する鋼種Ａは、Ｃｒ欠乏による鋭敏化現象と高いクロム炭化物の析出温度によりクロム炭窒化物が残留して最も低い孔食電位を示した。
固溶限以上のＮが添加されて窒素ガスピンホールが発生した鋼種Ｂの場合、Ｎの影響により最も高いＰＲＥＮ値と孔食電位を示したが、表面ピンホールの発生により製品への適用が不可能であった。
鋼種Ｃは、１７．２１のＰＲＥＮ値及び２１２ｍＶの高い孔食電位を示したが、Ｃ含量が高く、硬度が５４．７ＨＲＣと高く、上記した光沢のための研磨時に表面欠陥を防止できる適正な硬度範囲である４７～５３ＨＲＣを超えた。
Steel type A containing high carbon content of 0.6% or more exhibited the lowest pitting potential due to residual chromium carbonitride due to the sensitization phenomenon due to Cr deficiency and the high precipitation temperature of chromium carbide.
In the case of steel type B, in which nitrogen gas pinholes were generated due to the addition of N exceeding the solid solubility limit, the highest PREN value and pitting corrosion potential were exhibited due to the influence of N, but the occurrence of surface pinholes made it difficult to apply to products. It was impossible.
Steel type C showed a PREN value of 17.21 and a high pitting potential of 212 mV, but it has a high C content and a high hardness of 54.7 HRC, and has an appropriate hardness that can prevent surface defects during polishing for the above gloss. It exceeded the hardness range of 47 to 53 HRC.
鋼種Ｄ及びＥの場合、Ｃｒ及びＮ含量が類似しており、９５ｍＶ前後の類似の孔食電位値及び類似の硬度値を示した。
本発明鋼に該当する鋼種Ｆは、ＰＲＥＮ値が１６．５２で１６．０以上を示し、１９９ｍＶの優れた孔食電位値を示し、硬度値も５１．４ＨＲＣと適正水準を示した。
Steel grades D and E had similar Cr and N contents and exhibited similar pitting potential values around 95 mV and similar hardness values.
Steel type F, which corresponds to the steel of the present invention, showed a PREN value of 16.52, which is 16.0 or more, an excellent pitting corrosion potential value of 199 mV, and a hardness value of 51.4 HRC, which is an appropriate level.
図２及び図３は、鋼種Ｂと鋼種Ｆの熱延焼鈍鋼板の強化熱処理後に微細組織のクロム炭化物を観察した走査電子顕微鏡（ＳＥＭ）写真である。図２に示した鋼種Ｂは、高いＣ＋Ｎ含量により熱延焼鈍材にクロム炭窒化物を均一に分布できず、粗大化されて偏析され、クロム炭化物の析出温度も高く、強化熱処理後にも再固溶されず、残留することが確認できる。一方、発明鋼である鋼種Ｆは、Ｃ＋Ｎ、Ｃｒの含量とクロム炭化物の析出温度の制御を通じて強化熱処理後、ほとんどのクロム炭窒化物が再固溶され、断面に残留するクロム炭窒化物の面積分率２％以下を満たすことが分かる。 2 and 3 are scanning electron microscope (SEM) photographs of microstructures of chromium carbide observed after heat treatment for strengthening hot-rolled and annealed steel sheets of steel type B and steel type F. FIG. In steel grade B shown in FIG. 2, chromium carbonitrides cannot be uniformly distributed in the hot-rolled and annealed material due to the high C+N content, and are coarsened and segregated. It can be confirmed that it is not dissolved and remains. On the other hand, in the steel type F, which is the invention steel, most of the chromium carbonitrides are redissolved after the strengthening heat treatment by controlling the contents of C + N and Cr and the precipitation temperature of the chromium carbides, and the area of the chromium carbonitrides remaining in the cross section. It can be seen that the fraction 2% or less is satisfied.
上記のとおり、本発明の例示的な実施例を説明したが、本発明は、これに限定されず、当該技術分野で通常の知識を持つ者であれば、次に記載する請求範囲の概念と範囲を外れない範囲内で様々な変更及び変形が可能であることを理解できるだろう。 While illustrative embodiments of the present invention have been described above, the present invention is not so limited, and those of ordinary skill in the art will appreciate the concepts of the claims set forth below. It will be understood that various modifications and variations are possible without departing from the scope.
本発明によるマルテンサイト系ステンレス鋼は耐食性を向上させ、強化熱処理時に適正な硬度を確保できるので、洋食器の素材に適用可能である。 The martensitic stainless steel according to the present invention has improved corrosion resistance and can ensure proper hardness during heat treatment for strengthening, so it can be applied as a material for western tableware.
Claims (11)
微細組織内に２５個／１００μｍ２以上のクロム炭化物またはクロム窒化物が分布し、
前記クロム炭化物の析出温度が９５０℃以下であり、
下記式（１）のＰＲＥＮ値が１６以上であることを特徴とする高耐食マルテンサイト系ステンレス熱延焼鈍鋼板。
式（１）Ｃｒ＋３．３Ｍｏ＋１６Ｎ
（ここで、Ｃｒ、Ｍｏ、Ｎは、各合金元素の含量（重量％）を意味する） % by weight, C: 0.14-0.21%, N: 0.05-0.11%, Si: 0.1-0.6%, Mn: 0.4-1.2%, Cr: 14.0 to 17.0%, C + N: 0.2 to 0.32%, the rest consisting of Fe and unavoidable impurities,
25 pieces/100 μm 2 or more of chromium carbide or chromium nitride are distributed in the microstructure,
The precipitation temperature of the chromium carbide is 950° C. or less,
A highly corrosion-resistant martensitic stainless steel hot-rolled and annealed steel sheet characterized by having a PREN value of 16 or more in the following formula (1).
Formula (1) Cr+3.3Mo+16N
(Here, Cr, Mo, and N mean the content (% by weight) of each alloying element)
下記式（１）のＰＲＥＮ値が１６以上であり、
下記式（２）の値が９５０以下であることを特徴とする高耐食マルテンサイト系ステンレス鋼。
式（１）Ｃｒ＋３．３Ｍｏ＋１６Ｎ
式（２）６７４＋５６９Ｃ－４．１７Ｓｉ＋０．４６Ｍｎ＋１０．３Ｃｒ＋１９３Ｎ
（ここで、Ｃｒ、Ｍｏ、Ｎ、Ｃ、Ｓｉ、Ｍｎは、各合金元素の含量（重量％）を意味する） % by weight, C: 0.14-0.21%, N: 0.05-0.11%, Si: 0.1-0.6%, Mn: 0.4-1.2%, Cr: 14.0 to 17.0%, C + N: 0.2 to 0.32%, the rest consisting of Fe and unavoidable impurities,
The PREN value of the following formula (1) is 16 or more,
A highly corrosion-resistant martensitic stainless steel, wherein the value of the following formula (2) is 950 or less.
Formula (1) Cr+3.3Mo+16N
Formula (2) 674+569C-4.17Si+0.46Mn+10.3Cr+193N
(Here, Cr, Mo, N, C, Si, and Mn mean the content (% by weight) of each alloying element.)
熱延材をバッチ焼鈍熱処理する段階と、
熱延焼鈍材を強化熱処理する段階と、を含み、
前記バッチ焼鈍熱処理は、７２０～９００℃の温度範囲で５～２５時間第１の亀裂を処理する段階及び５００～７００℃の温度範囲で５～１５時間第２の亀裂を処理する段階を含み、
前記熱延焼鈍材は、フェライトを基地組織として２５個／１００μｍ２以上のクロム炭化物またはクロム窒化物が分布していることを特徴とする高耐食マルテンサイト系ステンレス鋼の製造方法。 % by weight, C: 0.14-0.21%, N: 0.05-0.11%, Si: 0.1-0.6%, Mn: 0.4-1.2%, Cr: 14.0 to 17.0%, C + N: 0.2 to 0.32%, and the balance is Fe and unavoidable impurities.
Batch annealing heat treatment of the hot-rolled material;
and heat-treating the hot-rolled annealed material for strengthening,
The batch annealing heat treatment includes treating the first crack at a temperature range of 720-900° C. for 5-25 hours and treating the second crack at a temperature range of 500-700° C. for 5-15 hours,
A method for producing highly corrosion-resistant martensitic stainless steel, wherein the hot-rolled and annealed material has ferrite as a matrix structure and 25 or more pieces/100 μm 2 of chromium carbide or chromium nitride are distributed.
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| KR10-2020-0034294 | 2020-03-20 | ||
| KR1020200034294A KR102326693B1 (en) | 2020-03-20 | 2020-03-20 | Martensitic stainless steel with excellent corrosion resistance and manufacturing method thereof |
| PCT/KR2020/014029 WO2021187706A1 (en) | 2020-03-20 | 2020-10-14 | Highly anticorrosive martensitic stainless steel, and manufacturing method therefor |
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| US (1) | US20230107193A1 (en) |
| EP (1) | EP4098765A4 (en) |
| JP (1) | JP2023517590A (en) |
| KR (1) | KR102326693B1 (en) |
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| KR20240125543A (en) * | 2021-12-20 | 2024-08-19 | 주식회사 포스코 | Martensitic stainless steel with improved softening resistance and its manufacturing method |
| CN115896591A (en) * | 2022-10-28 | 2023-04-04 | 中国科学院金属研究所 | Method for improving corrosion resistance and comprehensive mechanical property of low-carbon martensitic stainless steel |
| JP2024090519A (en) * | 2022-12-23 | 2024-07-04 | 大同特殊鋼株式会社 | Martensitic stainless steel material for hydrogen gas environment and its manufacturing method |
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| JP2010215995A (en) * | 2009-03-19 | 2010-09-30 | Nippon Steel & Sumikin Stainless Steel Corp | Martensitic stainless steel having excellent corrosion resistance |
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| JP3340225B2 (en) * | 1993-01-12 | 2002-11-05 | 新日本製鐵株式会社 | High strength martensitic stainless steel with excellent rust resistance and drilling tapping screw |
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| JP2000109957A (en) * | 1998-10-05 | 2000-04-18 | Sumitomo Metal Ind Ltd | Stainless steel for gasket and its production |
| KR100523107B1 (en) * | 2000-06-23 | 2005-10-19 | 주식회사 포스코 | Method for heat treating hot rolled 420-type martensitic stainless steel |
| JP4857811B2 (en) * | 2006-02-27 | 2012-01-18 | Ｊｆｅスチール株式会社 | Steel for knives |
| CN101372734A (en) * | 2007-08-24 | 2009-02-25 | 宝山钢铁股份有限公司 | Martensite stainless steel and manufacturing method thereof |
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| CN101693982B (en) * | 2009-09-30 | 2011-06-01 | 山西太钢不锈钢股份有限公司 | Martensite corrosion-resisting steel plate for cutting tool and manufacture method thereof |
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- 2020-03-20 KR KR1020200034294A patent/KR102326693B1/en active IP Right Grant
- 2020-10-14 EP EP20925160.2A patent/EP4098765A4/en active Pending
- 2020-10-14 WO PCT/KR2020/014029 patent/WO2021187706A1/en unknown
- 2020-10-14 US US17/908,124 patent/US20230107193A1/en active Pending
- 2020-10-14 CA CA3171590A patent/CA3171590A1/en active Pending
- 2020-10-14 CN CN202080098335.5A patent/CN115667569A/en active Pending
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| JPS527818A (en) * | 1975-07-09 | 1977-01-21 | Kawasaki Steel Corp | Process for producing rust proofing, medium carbon, martensitic, chrom ium stainless steel |
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| Publication number | Publication date |
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| EP4098765A1 (en) | 2022-12-07 |
| WO2021187706A1 (en) | 2021-09-23 |
| CN115667569A (en) | 2023-01-31 |
| EP4098765A4 (en) | 2024-04-24 |
| KR102326693B1 (en) | 2021-11-17 |
| CA3171590A1 (en) | 2021-09-23 |
| US20230107193A1 (en) | 2023-04-06 |
| KR20210117712A (en) | 2021-09-29 |
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