JP5745345B2 - Ferritic stainless steel sheet excellent in hot workability and weather resistance and manufacturing method thereof - Google Patents
Ferritic stainless steel sheet excellent in hot workability and weather resistance and manufacturing method thereof Download PDFInfo
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- 229910001220 stainless steel Inorganic materials 0.000 title claims description 70
- 238000004519 manufacturing process Methods 0.000 title claims description 16
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- 239000010959 steel Substances 0.000 claims description 39
- 238000000137 annealing Methods 0.000 claims description 20
- 229910052804 chromium Inorganic materials 0.000 claims description 18
- 229910052757 nitrogen Inorganic materials 0.000 claims description 16
- 229910052759 nickel Inorganic materials 0.000 claims description 15
- 229910052799 carbon Inorganic materials 0.000 claims description 14
- 238000005098 hot rolling Methods 0.000 claims description 14
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- 229910052802 copper Inorganic materials 0.000 claims description 12
- 229910052750 molybdenum Inorganic materials 0.000 claims description 11
- 229910052748 manganese Inorganic materials 0.000 claims description 10
- 229910052710 silicon Inorganic materials 0.000 claims description 10
- 239000000203 mixture Substances 0.000 claims description 9
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- 239000010935 stainless steel Substances 0.000 claims description 8
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- 229910052782 aluminium Inorganic materials 0.000 claims description 7
- 229910052698 phosphorus Inorganic materials 0.000 claims description 6
- 229910052726 zirconium Inorganic materials 0.000 claims description 6
- 229910052717 sulfur Inorganic materials 0.000 claims description 4
- 229910052727 yttrium Inorganic materials 0.000 claims description 4
- 229910052735 hafnium Inorganic materials 0.000 claims description 3
- 239000012535 impurity Substances 0.000 claims description 3
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- 229910000963 austenitic stainless steel Inorganic materials 0.000 description 2
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- 229910001208 Crucible steel Inorganic materials 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Description
本発明は、フェライト系ステンレス鋼板、特に、熱間加工性と耐銹性に優れた省合金型のフェライト系ステンレス鋼板と、その製造方法に関する。 The present invention relates to a ferritic stainless steel sheet, and more particularly to an alloy-saving ferritic stainless steel sheet excellent in hot workability and weather resistance and a method for producing the same.
フェライト系ステンレス鋼板は、家電・厨房機器及び建築建材の内外装用として、幅広い分野で使用されている。これは、フェライト系ステンレス鋼板が、レアメタルであり、近年、価格高騰の著しいＮｉを多量に含有するオ−ステナイト系ステンレス鋼板に比べ、経済性に優れているからである。 Ferritic stainless steel sheets are used in a wide range of fields for interior and exterior of home appliances, kitchen equipment, and building materials. This is because the ferritic stainless steel plate is a rare metal and is more economical than the austenitic stainless steel plate containing a large amount of Ni, which has recently experienced a significant increase in price.
Ｃｒを１１〜１３％程度含む低Ｃｒフェライト系ステンレス鋼には、ＪＩＳ鋼種で、ＳＵＳ４０５、ＳＵＳ４１０Ｌ、ＳＵＨ４０９、及び、Ｃ量を低減したＳＵＨ４０９Ｌなどがある。これらの低Ｃｒフェライト系ステンレス鋼は、ステンレス鋼の中で最も低廉で、良好な加工性を備えているが、Ｃｒ量が少ないので、耐食性には限界があり、家電・厨房機器及び建築建材などの一般耐久消費材として必要な耐食性を備えていない。 Low Cr ferritic stainless steels containing about 11 to 13% Cr are JIS steel types such as SUS405, SUS410L, SUH409, and SUH409L with reduced C content. These low Cr ferritic stainless steels are the cheapest of all stainless steels and have good workability. However, the amount of Cr is small, so there is a limit to corrosion resistance, such as home appliances / kitchen equipment and building / building materials. It does not have the necessary corrosion resistance as a general durable consumer material.
そのため、一般耐久消費材としての用途には、Ｃｒを１４〜２０％程度を含む中Ｃｒフェライト系ステンレス鋼が広く使用されている。その中でも、Ｃｒを１７％程度含むＳＵＳ４３０が特に使用されている。 Therefore, medium Cr ferritic stainless steel containing about 14 to 20% of Cr is widely used for applications as a general durable consumer material. Among them, SUS430 containing about 17% of Cr is particularly used.
前記用途に用いる中Ｃｒフェライト系ステンレス鋼には、中性塩化物環境での孔食、発銹に対する耐食性が優れていることが要求される。通常、ＳＵＳ４３０の耐食性を改善するためにＣやＮを低減するが、ＳＵＳ４３０の他、ＣやＮを低減し、ＮｂやＴｉなどの安定化元素を添加した高純度フェライト系ステンレス鋼がある。 The medium Cr ferritic stainless steel used in the above applications is required to have excellent corrosion resistance against pitting and rusting in a neutral chloride environment. Usually, C and N are reduced to improve the corrosion resistance of SUS430. In addition to SUS430, there are high purity ferritic stainless steels in which C and N are reduced and a stabilizing element such as Nb and Ti is added.
ＪＩＳ鋼種としては、ＳＵＳ４３０ＬＸがあり、ＳＵＳ４３０ＬＸの上位鋼種として、Ｃｕ、Ｎｉ、Ｍｏなどを添加し、かつ、Ｃｒ量を増大したＳＵＳ４３０Ｊ１ＬやＳＵＳ４３６Ｊ１Ｌなどがある。 As a JIS steel grade, there is SUS430LX, and as a higher grade steel grade of SUS430LX, there are SUS430J1L, SUS436J1L, etc. in which Cu, Ni, Mo, etc. are added and the Cr amount is increased.
Ｎｉ、Ｍｏ、Ｎｂ、Ｔｉに加え、ステンレス鋼の主要元素であるＣｒは、レアメタルであり、価格変動に伴う経済性の問題を抱えている。それ故、これらレアメタルの使用に依存せずに、低Ｃｒフェライト系ステンレス鋼及びＳＵＳ４３０の耐食性を改善して、用途を拡大することが課題となる。 In addition to Ni, Mo, Nb, and Ti, Cr, which is a main element of stainless steel, is a rare metal and has an economic problem associated with price fluctuations. Therefore, without depending on the use of these rare metals, it becomes a problem to improve the corrosion resistance of the low Cr ferritic stainless steel and SUS430 to expand the application.
省資源及び経済性の観点から上記課題を解決するため、微量のＳｎやＳｂを添加して、低Ｃｒフェライト系ステンレス鋼の耐粒界腐食性を改善する検討がなされている。 In order to solve the above problems from the viewpoint of resource saving and economical efficiency, studies have been made to improve the intergranular corrosion resistance of low Cr ferritic stainless steel by adding a small amount of Sn or Sb.
特許文献１には、Ｃ：０．００１〜０．３０％、Ｎ：０．００１〜０．０５０％、Ｃｒ：１０．０〜３０．０％、Ｓ：０．０１０％以下、Ｐ：０．０４０％以下、Ｍｎ：０．０１〜１．０％、Ｓｉ：０．０１〜１．０％、Ｎｉ：１．０％以下、Ｏ：０．０１０％以下を含有し、Ｓｎ：０．００５〜０．１０％、Ｓｂ：０．００５〜０．１０％の１種又は２種を含有する表面性状に優れたフェライト系ステンレス鋼が開示されている。このステンレス鋼におけるＳｎ及びＳｂの量は、実質的には０．０５％未満である。 In Patent Document 1, C: 0.001 to 0.30%, N: 0.001 to 0.050%, Cr: 10.0 to 30.0%, S: 0.010% or less, P: 0 0.040% or less, Mn: 0.01 to 1.0%, Si: 0.01 to 1.0%, Ni: 1.0% or less, O: 0.010% or less, Sn: 0.0. Ferritic stainless steels having excellent surface properties containing one or two of 005 to 0.10% and Sb: 0.005 to 0.10% are disclosed. The amount of Sn and Sb in this stainless steel is substantially less than 0.05%.
特許文献２には、Ｃ：０．０３〜０．２５％、Ｓｉ：０．２５〜０．６％、Ｍｎ：２％以下、Ｐ：０．０３５％以下、Ｓ：０．０１％以下、Ｃｒ：１１〜１５．５％、Ｎｉ：０．６％以下、Ｃｕ：０．８％以下、Ｍｏ：０．０５％以下、Ｓｎ：０．０３〜０．１５％、Ｖ：０．１％以下、Ａｌ：０．０３％以下、Ｎ：０．０１〜０．０８％を含有し、３００〜６００Ｈｖの高硬度を特徴とした耐食性に優れたマルテンサイト系ステンレス鋼が開示されている。 In Patent Document 2, C: 0.03 to 0.25%, Si: 0.25 to 0.6%, Mn: 2% or less, P: 0.035% or less, S: 0.01% or less, Cr: 11 to 15.5%, Ni: 0.6% or less, Cu: 0.8% or less, Mo: 0.05% or less, Sn: 0.03 to 0.15%, V: 0.1% Hereinafter, martensitic stainless steel containing Al: 0.03% or less and N: 0.01-0.08% and having a high hardness of 300-600 Hv and excellent in corrosion resistance is disclosed.
特許文献３〜５には、Ｍｇの微量添加を前提として、非金属介在物の制御と耐食性改善に効果がある、Ｗ、Ｖ、Ｚｒ、Ｃｏ、Ｓｅ、Ｔａ、Ｒｅ、Ｙ、Ｌａ、ＨｆのレアメタルやＳｎを微量添加した、耐食性、表面特性、加工性に優れたフェライト系ステンレス鋼が開示されている。 Patent Documents 3 to 5 have the effect of controlling non-metallic inclusions and improving corrosion resistance on the premise of adding a small amount of Mg. W, V, Zr, Co, Se, Ta, Re, Y, La, Hf A ferritic stainless steel having a small amount of rare metal or Sn added and excellent in corrosion resistance, surface characteristics, and workability is disclosed.
特許文献３及び５に記載のフェライト系ステンレス鋼は、Ｃ、Ｎを低減し、ＴｉやＮｂなどの安定化元素を添加した高純度フェライト系ステンレス鋼である。特許文献４に記載のフェライト系ステンレス鋼は、Ｍｇ：１２〜６０ｐｐｍ、Ｃ：０．０３９〜０．１％、Ｎ：０．０００２〜０．０５％の高Ｍｇ含有フェライト系ステンレス鋼である。 The ferritic stainless steels described in Patent Documents 3 and 5 are high-purity ferritic stainless steels in which C and N are reduced and stabilizing elements such as Ti and Nb are added. The ferritic stainless steel described in Patent Document 4 is a high-Mg ferritic stainless steel with Mg: 12 to 60 ppm, C: 0.039 to 0.1%, and N: 0.0002 to 0.05%.
これまで、本発明者らは、省資源及び経済性の観点から、ＣｒやＭｏの添加によらず、Ｓｎの添加により耐銹性や加工性を改善した高純度フェライト系ステンレス鋼を開示している。Ｓｎは、Ｃｕとともに、鉄鋼材料において代表的なトランプエレメントであるので、リサイクルした鉄源をＳｎ源として有効に利用できる。 So far, the present inventors have disclosed a high-purity ferritic stainless steel that has improved weather resistance and workability by the addition of Sn, not from the addition of Cr or Mo, from the viewpoint of resource saving and economy. Yes. Sn, together with Cu, is a typical trump element in steel materials, and thus a recycled iron source can be effectively used as the Sn source.
特許文献６及び７には、Ｃｒ：１３〜２２％、Ｓｎ：０．００１〜１％で、Ｃ、Ｎ、Ｓｉ、Ｍｎ、Ｐを低減し、必要に応じて、ＴｉやＮｂの安定化元素を添加した高純度フェライト系ステンレス鋼が開示されている。 Patent Documents 6 and 7 include Cr: 13 to 22%, Sn: 0.001 to 1%, reducing C, N, Si, Mn, and P, and stabilizing elements of Ti and Nb as necessary. A high-purity ferritic stainless steel to which is added is disclosed.
これまで、低Ｃｒフェライト系ステンレス鋼において、レアメタルに頼らずに、ＳｎやＭｇの微量添加で耐食性を改善することが検討されているが、検討対象は、その添加量が０．０５％未満のフェライト系ステンレス鋼に限られていた。それ故、低Ｃｒフェライト系ステンレス鋼は、一般耐久消費材に適用し得る耐食性を備えるまでに至っていない。 So far, in low Cr ferritic stainless steel, it has been studied to improve the corrosion resistance by adding a small amount of Sn or Mg without relying on rare metals, but the object of study is that the added amount is less than 0.05% It was limited to ferritic stainless steel. Therefore, low Cr ferritic stainless steel has not yet been provided with corrosion resistance that can be applied to general durable consumer materials.
Ｓｎの添加効果は、Ｈｖ３００以上のマルテンサイト系ステンレス鋼や、ＣやＮを低減した高純度フェライト系ステンレス鋼で発現するが、用途の拡大を図るのに充分な耐食性は得られていない。 The effect of addition of Sn is manifested in martensitic stainless steel with a Hv of 300 or higher, or high-purity ferritic stainless steel with reduced C and N, but sufficient corrosion resistance is not obtained for expansion of applications.
そこで、本発明は、レアメタルに頼ることなく，リサイクルした鉄源から有効利用が期待できるＳｎに着眼し、低Ｃｒフェライト系ステンレス鋼の耐食性を改善して、一般耐久消費材への適用が可能な省合金型のフェライト系ステンレス鋼板を提供することを目的とする。 Therefore, the present invention focuses on Sn that can be expected to be effectively used from recycled iron sources without relying on rare metals, and can improve the corrosion resistance of low Cr ferritic stainless steel and can be applied to general durable consumer materials. An object is to provide an alloy-saving ferritic stainless steel sheet.
本発明者らは、Ｓｎを添加して、低Ｃｒフェライト系ステンレス鋼の耐食性を改善するにあたり、熱間加工性の改善が製造上の課題となることを見いだした。非特許文献２には、Ｓｎはステンレス鋼の熱間加工性を阻害し、オーステナイト系ステンレス鋼においてはＳｎ＜０．０１％と低く抑えることが開示されているが、Ｓｎを添加したフェライト系ステンレス鋼ついては具体的な開示がなく、これまで課題として認識されていない。 The inventors of the present invention have found that improvement of hot workability becomes a manufacturing problem when Sn is added to improve the corrosion resistance of the low Cr ferritic stainless steel. Non-Patent Document 2 discloses that Sn inhibits the hot workability of stainless steel, and in an austenitic stainless steel, it is disclosed that Sn <0.01% is kept low. There is no specific disclosure about steel and it has not been recognized as a problem so far.
本発明者らは、前記課題を解決するため、低Ｃｒフェライト系ステンレス鋼において、耐銹性と、Ｓｎ添加で製造上の課題となる熱間加工性に着眼して鋭意研究し、下記（ａ）〜（ｄ）の知見を得るに至った。 In order to solve the above-mentioned problems, the present inventors have intensively studied on the low Cr ferritic stainless steel, focusing on the weather resistance and the hot workability that is a manufacturing problem due to the addition of Sn. ) To (d) were obtained.
（ａ）Ｓｎは、高純度フェライト系ステンレス鋼の耐銹性の向上に有効な元素であるが、高純度フェライト系ステンレス鋼に限らす、低Ｃｒフェライト系ステンレス鋼及び中Ｃｒフェライト系ステンレス鋼においても、微量のＳｎ添加で耐銹性が向上し、かつ、下記式で定義するγｐを１０≦γｐ≦６５に調整すると、良好な熱間加工性を得ることができる。なお、下記式の技術的意味については後述する。 (A) Sn is an element effective for improving the weather resistance of high purity ferritic stainless steel, but is limited to high purity ferritic stainless steel, in low Cr ferritic stainless steel and medium Cr ferritic stainless steel However, when a small amount of Sn is added, the weather resistance is improved, and when γp defined by the following formula is adjusted to 10 ≦ γp ≦ 65, good hot workability can be obtained. The technical meaning of the following formula will be described later.
γｐ＝４２０Ｃ＋４７０Ｎ＋２３Ｎｉ＋７Ｍｎ＋９Ｃｕ−１１．５Ｃｒ
−１１．５Ｓｉ−５２Ａｌ−６９Ｓｎ＋１８９
γｐは、非特許文献１で開示されている、１１００℃加熱時に生成するオーステナイト量の最大値を表す指標である。
γp = 420C + 470N + 23Ni + 7Mn + 9Cu-11.5Cr
-11.5Si-52Al-69Sn + 189
γp is an index that represents the maximum value of the amount of austenite generated during heating at 1100 ° C. disclosed in Non-Patent Document 1.
（ｂ）熱間加工性は、ＣやＮを低減して高温での変形抵抗を下げるか、又は、Ｍｇ、Ｂ、Ｃａなどを微量添加して粒界強度を高めることで改善できる。 (B) Hot workability can be improved by reducing C and N to reduce deformation resistance at high temperatures, or adding a small amount of Mg, B, Ca, etc. to increase grain boundary strength.
（ｃ）また、熱間加工性は、スラブ加熱温度と熱延終了温度を高くして高温での変形抵抗を小さくすることで改善できる。 (C) Moreover, the hot workability can be improved by increasing the slab heating temperature and the hot rolling end temperature to reduce the deformation resistance at a high temperature.
（ｄ）耐銹性は、Ｎｂ、Ｔｉの安定化元素を添加するか、又は、リサクルした鉄源からＮｉ、Ｃｕ、Ｍｏ、Ｖなどが混入することで改善できる。 (D) The weather resistance can be improved by adding a stabilizing element of Nb or Ti, or by mixing Ni, Cu, Mo, V, or the like from the recycled iron source.
本発明は、上記（ａ）〜（ｄ）の知見に基づいてなされたもので、その要旨は、以下の通りである。 This invention was made | formed based on the knowledge of said (a)-(d), and the summary is as follows.
（１）質量％で、Ｃ：０．００１〜０．３％、Ｓｉ：０．０１〜１．０％、Ｍｎ：０．０１〜２．０％、Ｐ：０．００５〜０．０５％、Ｓ：０．０００１〜０．０１％、Ｃｒ：１１．０〜１３．０％、Ｎ：０．００１〜０．１％、Ａｌ：０．０００１〜１．０％、Ｓｎ：０．０５〜１．０％、残部Ｆｅ及び不可避的不純物からなるフェライト系ステンレス鋼板において、下記式（２）で定義するγｐが、下記式（１）を満たすことを特徴とする熱間加工性と耐銹性に優れたフェライト系ステンレス鋼板。
１０≦γｐ≦６５ ・・・（１）
γｐ＝４２０Ｃ＋４７０Ｎ＋２３Ｎｉ＋７Ｍｎ＋９Ｃｕ−１１．５Ｃｒ
−１１．５Ｓｉ−５２Ａｌ−６９Ｓｎ＋１８９ ・・・（２）
ここで、Ｃ、Ｎ、Ｎｉ、Ｍｎ、Ｃｕ、Ｃｒ、Ｓｉ、Ａｌ、及び、Ｓｎは、各元素の含有量。
(1) By mass%, C: 0.001 to 0.3%, Si: 0.01 to 1.0%, Mn: 0.01 to 2.0%, P: 0.005 to 0.05% , S: 0.0001 to 0.01%, Cr: 11.0 to 13.0%, N: 0.001 to 0.1%, Al: 0.0001 to 1.0%, Sn: 0.05 In a ferritic stainless steel sheet composed of ~ 1.0%, the remainder Fe and inevitable impurities, γp defined by the following formula (2) satisfies the following formula (1) and hot workability and wrinkle resistance Ferritic stainless steel sheet with excellent properties.
10 ≦ γp ≦ 65 (1)
γp = 420C + 470N + 23Ni + 7Mn + 9Cu-11.5Cr
-11.5Si-52Al-69Sn + 189 (2)
Here, C, N, Ni, Mn, Cu, Cr, Si, Al, and Sn are the contents of each element.
（２）前記式（１）に替え、下記式（１’）を満たすことを特徴とする前記（１）に記載の熱間加工性と耐銹性に優れたフェライト系ステンレス鋼板。
１５≦γｐ≦５５ ・・・（１’）
(2) The ferritic stainless steel sheet excellent in hot workability and weather resistance according to (1), wherein the following expression (1 ′) is satisfied instead of the expression (1).
15 ≦ γp ≦ 55 (1 ′)
（３）前記フェライト系ステンレス鋼板が、さらに、質量％で、Ｍｇ：０．００５％以下、Ｂ：０．００５％以下、Ｃａ：０．００５％以下、Ｌａ：０．１％以下、Ｙ：０．１％以下、Ｈｆ：０．１％以下、ＲＥＭ：０．１％以下の１種又は２種以上を含有することを特徴とする前記（１）又は（２）に記載の熱間加工性と耐銹性に優れたフェライト系ステンレス鋼板。 (3) The ferritic stainless steel sheet is further, in mass%, Mg: 0.005% or less, B: 0.005% or less, Ca: 0.005% or less, La: 0.1% or less, Y: One or more of 0.1% or less, Hf: 0.1% or less, and REM: 0.1% or less are included. Hot working as described in (1) or (2) above Ferritic stainless steel sheet with excellent durability and weather resistance.
（４）前記フェライト系ステンレス鋼板が、さらに、質量％で、Ｎｂ：０．３％以下、Ｔｉ：０．３％以下、Ｎｉ：１．０％以下、Ｃｕ：１．０％以下、Ｍｏ：１．０％以下、Ｖ：１．０％以下、Ｚｒ：０．５％以下、Ｃｏ：０．５％以下の１種又は２種以上を含有することを特徴とする前記（１）〜（３）のいずれかに記載の熱間加工性と耐銹性に優れたフェライト系ステンレス鋼板。 (4) The ferritic stainless steel sheet is further in mass%, Nb: 0.3% or less, Ti: 0.3% or less, Ni: 1.0% or less, Cu: 1.0% or less, Mo: 1.0% or less, V: 1.0% or less, Zr: 0.5% or less, Co: 0.5% or less, containing one or more kinds (1) to ( 3) A ferritic stainless steel sheet excellent in hot workability and weather resistance according to any one of 3).
（５）前記（１）〜（４）のいずれかに記載の成分組成を有するステンレス鋼スラブを１１００〜１３００℃に加熱して熱間圧延に供し、熱間圧延終了後の鋼板を７００〜１０００℃で巻き取ることを特徴とする熱間加工性と耐銹性に優れたフェライト系ステンレス鋼板の製造方法。 (5) The stainless steel slab having the composition according to any one of (1) to (4) is heated to 1100 to 1300 ° C. and subjected to hot rolling, and the steel sheet after hot rolling is finished is 700 to 1000. A method for producing a ferritic stainless steel sheet excellent in hot workability and weather resistance, characterized by winding at ℃.
（６）前記熱間圧延終了後の鋼板に、焼鈍を施さないか、又は、７００〜１０００℃で連続焼鈍又は箱焼鈍を施すことを特徴とする前記（５）に記載の熱間加工性と耐銹性に優れたフェライト系ステンレス鋼板の製造方法。 (6) The hot workability as described in (5) above, wherein the steel sheet after the hot rolling is not annealed, or is subjected to continuous annealing or box annealing at 700 to 1000 ° C. A method for producing ferritic stainless steel sheets with excellent weather resistance.
本発明によれば、レアメタルに頼らずに、リサイクルした鉄源中のＳｎを有効に利用して、低Ｃｒフェライト系ステンレス鋼の耐食性を改善して、一般耐久消費材への適用が可能な省合金型のフェライト系ステンレス鋼板を提供することができる。 According to the present invention, the corrosion resistance of low Cr ferritic stainless steel can be improved by effectively using Sn in a recycled iron source without relying on rare metals, and can be applied to general durable consumer goods. An alloy type ferritic stainless steel sheet can be provided.
以下、本発明について説明する。 The present invention will be described below.
本発明の熱間加工性と耐銹性に優れたフェライト系ステンレス鋼板（以下「本発明鋼板」ということがある。）は、質量％で、Ｃ：０．００１〜０．３％、Ｓｉ：０．０１〜１．０％、Ｍｎ：０．０１〜２．０％、Ｐ：０．００５〜０．０５％、Ｓ：０．０００１〜０．０１％、Ｃｒ：１１．０〜１３．０％、Ｎ：０．００１〜０．１％、Ａｌ：０．０００１〜１．０％、Ｓｎ：０．０５〜１．０％、残部Ｆｅ及び不可避的不純物からなるフェライト系ステンレス鋼板において、下記式（２）で定義するγｐが、下記式（１）を満たすことを特徴とする。 The ferritic stainless steel sheet (hereinafter sometimes referred to as “the present invention steel sheet”) excellent in hot workability and weather resistance of the present invention is in mass%, C: 0.001 to 0.3%, Si: 0.01-1.0%, Mn: 0.01-2.0%, P: 0.005-0.05%, S: 0.0001-0.01%, Cr: 11.0-13. In a ferritic stainless steel sheet consisting of 0%, N: 0.001 to 0.1%, Al: 0.0001 to 1.0%, Sn: 0.05 to 1.0%, the balance Fe and inevitable impurities, Γp defined by the following formula (2) satisfies the following formula (1).
１０≦γｐ≦６５ ・・・（１）
γｐ＝４２０Ｃ＋４７０Ｎ＋２３Ｎｉ＋７Ｍｎ＋９Ｃｕ−１１．５Ｃｒ
−１１．５Ｓｉ−５２Ａｌ−６９Ｓｎ＋１８９ ・・・（２）
ここで、Ｃ、Ｎ、Ｎｉ、Ｍｎ、Ｃｕ、Ｃｒ、Ｓｉ、Ａｌ、及び、Ｓｎは、各元素の含有量である。
10 ≦ γp ≦ 65 (1)
γp = 420C + 470N + 23Ni + 7Mn + 9Cu-11.5Cr
-11.5Si-52Al-69Sn + 189 (2)
Here, C, N, Ni, Mn, Cu, Cr, Si, Al, and Sn are the contents of each element.
（Ｉ）本発明鋼板の成分組成を限定する理由を、まず説明する。以下、「％」は「質量％」を意味する。 (I) The reason for limiting the component composition of the steel sheet of the present invention will be described first. Hereinafter, “%” means “mass%”.
Ｃは、熱間加工性と耐銹性の劣化させる元素である。熱間加工性と耐銹性の劣化を抑制するため、上限を０．３％とする。過度の低減は精錬コストの増加に繋がるので、下限を０．００１％とする。好ましくは、製造性や耐銹性を考慮して０．０１〜０．１％とする。より好ましくは０．０２〜０．０７％である。 C is an element that degrades hot workability and weather resistance. In order to suppress deterioration of hot workability and weather resistance, the upper limit is made 0.3%. Since excessive reduction leads to an increase in refining costs, the lower limit is made 0.001%. Preferably, considering the manufacturability and weather resistance, the content is made 0.01 to 0.1%. More preferably, it is 0.02 to 0.07%.
Ｓｉは、脱酸元素として有効であり、かつ、耐銹性を高める元素である。添加効果を得るため、０．０１％以上を添加する。過度な添加は靭性や加工性の低下を招くので、上限を１．０％とする。好ましくは、添加効果と製造性を考慮して０．１〜０．６％とする。より好ましくは０．１５〜０．５％である。 Si is an element that is effective as a deoxidizing element and enhances weather resistance. In order to obtain the effect of addition, 0.01% or more is added. Excessive addition causes a decrease in toughness and workability, so the upper limit is made 1.0%. Preferably, considering the addition effect and manufacturability, 0.1 to 0.6%. More preferably, it is 0.15 to 0.5%.
Ｍｎは、硫化物を形成して、耐銹性を阻害する元素である。耐銹性の低下を抑制するため、上限を２．０％とする。過度の低減は精錬コストの増加に繋がるので、下限を０．０１％とする。好ましくは、耐銹性と製造性を考慮して０．０５〜０．６％とする。より好ましくは０．１５〜０．５％である。 Mn is an element that forms sulfides and inhibits weather resistance. In order to suppress deterioration of weather resistance, the upper limit is made 2.0%. Excessive reduction leads to an increase in refining costs, so the lower limit is made 0.01%. Preferably, considering the weather resistance and manufacturability, the content is made 0.05 to 0.6%. More preferably, it is 0.15 to 0.5%.
Ｐは、製造性や溶接性を阻害する元素である。製造性や溶接性の低下を抑制するため、上限を０．０５％とする。過度の低減は精錬コストの増加に繋がるので、下限を０．００５％とする。好ましくは、製造コストを考慮して０．０１〜０．０４％とする。より好ましくは０．０１〜０．０３％である。 P is an element that inhibits manufacturability and weldability. The upper limit is made 0.05% in order to suppress degradation of manufacturability and weldability. Since excessive reduction leads to an increase in refining costs, the lower limit is made 0.005%. Preferably, considering the manufacturing cost, the content is made 0.01 to 0.04%. More preferably, it is 0.01 to 0.03%.
Ｓは、熱間加工性や耐銹性を劣化させる元素である。熱間加工性や耐銹性の劣化を抑制するため、上限を０．０２％とする。過度の低減は精錬コストの増加に繋がるので、下限を０．０００１％とする。好ましくは、耐銹性や製造コストを考慮して０．０００２〜０．０１％とする。より好ましくは０．０００５〜０．００５％である。 S is an element that deteriorates hot workability and weather resistance. In order to suppress deterioration of hot workability and weather resistance, the upper limit is made 0.02%. Since excessive reduction leads to an increase in refining costs, the lower limit is made 0.0001%. Preferably, considering the weather resistance and manufacturing cost, the content is made 0.0002 to 0.01%. More preferably, it is 0.0005 to 0.005%.
Ｃｒは、Ｓｎを添加した本発明鋼板の耐銹性を高めるのに必須の元素である。耐銹性向上作用を得るため、１１．０％以上を添加する。上限は、製造性と耐食性の観点から１３．０％とする。性能と合金コストを考慮すると、１２．０〜１３．０％が好ましい。 Cr is an essential element for enhancing the weather resistance of the steel sheet of the present invention to which Sn is added. In order to obtain an effect of improving weather resistance, 11.0% or more is added. The upper limit is 13.0% from the viewpoints of manufacturability and corrosion resistance. Considering performance and alloy cost, 12.0 to 13.0% is preferable.
Ｎは、Ｃと同様に耐銹性を劣化させる元素である。耐銹性の劣化を抑制するため、上限を０．１％とする。過度の低減は精錬コストの増加に繋がるので、下限を０．００１％とする。好ましくは、耐銹性や製造コストを考慮して０．０１〜０．０５％とする。より好ましくは０．０１〜０．０３％である。 N, like C, is an element that degrades weather resistance. In order to suppress deterioration of weather resistance, the upper limit is made 0.1%. Since excessive reduction leads to an increase in refining costs, the lower limit is made 0.001%. Preferably, considering the weather resistance and manufacturing cost, 0.01 to 0.05%. More preferably, it is 0.01 to 0.03%.
Ａｌは、Ｓｉと同様に脱酸に有効で、かつ、耐銹性を高める元素である。添加効果を得るため、０．０００１％以上を添加する。過度の添加は靭性や溶接性の低下を招くので、上限を１．０％とする。好ましくは、添加効果と製造性を考慮して０．００１〜０．５％とする。より好ましくは０．００５〜０．１％である。 Al, like Si, is an element that is effective for deoxidation and enhances weather resistance. In order to obtain the additive effect, 0.0001% or more is added. Excessive addition causes a decrease in toughness and weldability, so the upper limit is made 1.0%. Preferably, considering the addition effect and manufacturability, the content is made 0.001 to 0.5%. More preferably, it is 0.005 to 0.1%.
Ｓｎは、Ｃｒ、Ｎｉ、Ｍｏ等のレアメタルに頼ることなく、目標とする耐銹性を確保するのに必須の元素である。また，Ｓｎは、フェラト形成元素として作用し、γｐを小さくするとともに，接種効果により、凝固組織を微細化する元素である。そのため，従来、γｐが小さい時に発生する鋼塊の置き割れは、Ｓｎ添加による凝固組織の微細化で改善できる。 Sn is an essential element for ensuring the target weather resistance without relying on rare metals such as Cr, Ni, and Mo. Sn is an element that acts as a ferrite forming element, reduces γp, and refines the solidified structure by the inoculation effect. Therefore, conventionally, the cracking of the steel ingot generated when γp is small can be improved by refining the solidified structure by adding Sn.
本発明鋼板においては、目標とする耐銹性を得るため、０．０５％以上を添加する。上限は、製造性の観点から１．０％とする。ＳＵＳ４３０と比較した経済性から、好ましくは０．１０超〜０．６％とする。性能と合金コストを考慮すると、０．１０超〜０．３％がより好ましい。 In the steel sheet of the present invention, 0.05% or more is added to obtain the target weather resistance. The upper limit is 1.0% from the viewpoint of manufacturability. From the economical efficiency compared with SUS430, it is preferably more than 0.10 to 0.6%. Considering performance and alloy cost, more than 0.10 to 0.3% is more preferable.
Ｍｇ、Ｂ、Ｃａは、鋼の清浄度又は粒界強度を高め、Ｓｎ添加鋼の熱間加工性を改善するのに有効な元素である。必要に応じて、いずれも０．０００１％以上添加するが、０．００５％を超えると、製造性が低下するので、いずれも、上限を０．００５％とする。好ましくは、効果と製造性を考慮して０．０００３〜０．００３％とする。 Mg, B, and Ca are elements that are effective in increasing the cleanliness or grain boundary strength of steel and improving the hot workability of Sn-added steel. If necessary, both are added in an amount of 0.0001% or more. However, if it exceeds 0.005%, the productivity is lowered. Preferably, considering the effect and manufacturability, the content is made 0.0003 to 0.003%.
Ｌａ、Ｙ、Ｈｆ、ＲＥＭは、熱間加工性や鋼の清浄度を高め、耐銹性や熱間加工性を著しく向上させる元素である。必要に応じて、いずれも０．００１％以上添加するが、過度の添加は、合金コストの上昇と製造性の低下に繋がるので、いずれも、上限を０．１％とする。好ましくは、添加効果、経済性、及び、製造性を考慮して、１種又は２種以上の合計で０．００１〜０．０５％とする。 La, Y, Hf, and REM are elements that increase hot workability and steel cleanliness, and significantly improve weather resistance and hot workability. If necessary, both are added in an amount of 0.001% or more. However, excessive addition leads to an increase in alloy cost and a decrease in manufacturability, so in both cases the upper limit is set to 0.1%. Preferably, considering the effect of addition, economy, and manufacturability, the total of one or more types is 0.001 to 0.05%.
ＮｂとＴｉは、Ｃ、Ｎを固定する安定化作用により、耐銹性を向上させる元素である。必要に応じて、いずれも０．０１％以上添加するが、過度の添加は、合金コストの上昇や再結晶温度上昇に伴う製造性の低下に繋がるので、いずれも、上限を０．３％とする。好ましくは、添加効果、合金コスト、及び、製造性を考慮して、Ｎｂ、Ｔｉの１種又は２種の合計で０．０２〜０．２％とする。 Nb and Ti are elements that improve weather resistance by a stabilizing action of fixing C and N. If necessary, both are added in an amount of 0.01% or more. However, excessive addition leads to a decrease in manufacturability accompanying an increase in alloy costs and a recrystallization temperature. To do. Preferably, considering the addition effect, alloy cost, and manufacturability, the total of one or two of Nb and Ti is 0.02 to 0.2%.
Ｎｉ、Ｃｕ、Ｍｏ、Ｖ、Ｚｒ、Ｃｏは、Ｓｎとの相乗効果で耐銹性を高める元素である。必要に応じて添加するが、Ｎｉ、Ｃｕ、Ｍｏは、いずれも０．１％以上を添加し、Ｖ、Ｚｒ、Ｃｏは、いずれも０．０１％以上を添加する。過度の添加は、合金コストの上昇や製造性の低下に繋がるので、Ｎｉ、Ｃｕ、Ｍｏ、Ｖは、上限を１．０％とし、Ｚｒ、Ｃｏは、上限を０．５％とする。 Ni, Cu, Mo, V, Zr, and Co are elements that enhance weather resistance by a synergistic effect with Sn. Although it adds as needed, Ni, Cu, and Mo all add 0.1% or more, and V, Zr, and Co all add 0.01% or more. Excessive addition leads to an increase in alloy costs and a decrease in manufacturability. Therefore, Ni, Cu, Mo, and V have an upper limit of 1.0%, and Zr and Co have an upper limit of 0.5%.
（II）次に、式（２）で定義するγｐと、Ｓｎ添加鋼の熱間加工性を確保するため、γｐの範囲を限定する式（１）について説明する。γｐは、１１００℃に加熱した時に生成するオーステナイト量の最大値を示す指標である。本発明者らは、Ｓｎの添加効果を実験的に求め、非特許文献１に記載されているγ相の最大相分率を推定する経験式に、Ｓｎの項「−６９Ｓｎ」を新たに加え、下記式を得た。 (II) Next, γp defined by formula (2) and formula (1) for limiting the range of γp in order to ensure the hot workability of the Sn-added steel will be described. γp is an index indicating the maximum amount of austenite produced when heated to 1100 ° C. The present inventors experimentally obtained the effect of addition of Sn, and newly added the Sn term “−69Sn” to the empirical formula for estimating the maximum phase fraction of the γ phase described in Non-Patent Document 1. The following formula was obtained.
γｐ＝４２０Ｃ＋４７０Ｎ＋２３Ｎｉ＋７Ｍｎ＋９Ｃｕ−１１．５Ｃｒ
−１１．５Ｓｉ−５２Ａｌ−６９Ｓｎ＋１８９
ここで、Ｃ、Ｎ、Ｎｉ、Ｍｎ、Ｃｕ、Ｃｒ、Ｓｉ、Ａｌ、及び、Ｓｎは、各元素の含有量である。
γp = 420C + 470N + 23Ni + 7Mn + 9Cu-11.5Cr
-11.5Si-52Al-69Sn + 189
Here, C, N, Ni, Mn, Cu, Cr, Si, Al, and Sn are the contents of each element.
本発明者らが実施した実験とその結果、及び、推察される作用機構について説明する。０．２％のＳｎを含有する１１〜１３％Ｃｒ鋼を、５０ｋｇ、真空中で溶解し、鋳造した鋼塊から４２ｍｍ厚のブロック試験片を作製し、１カ月間放置した後、熱間圧延実験を行った。 The experiment conducted by the present inventors, the result thereof, and the presumed action mechanism will be described. A 11-13% Cr steel containing 0.2% Sn was melted in a vacuum of 50 kg, a 42 mm thick block test piece was prepared from the cast steel ingot, left standing for one month, and then hot rolled. The experiment was conducted.
熱間圧延実験においては、ブロック試験片を１１２０℃に加熱し、総圧下率８８％（８パス）、仕上げ温度７００〜９００℃で、５ｍｍ厚の熱延板を製造し、熱延板の両サイドで耳割れ発生の有無を調査し、熱間加工性の良否を判定した。 In the hot rolling experiment, the block test piece was heated to 1120 ° C., a hot-rolled sheet having a total reduction ratio of 88% (8 passes), a finishing temperature of 700 to 900 ° C. and a thickness of 5 mm was manufactured. The presence or absence of the occurrence of ear cracks was investigated on the side, and the quality of hot workability was judged.
耳割れは、γｐの上昇に伴い発生し、１３％Ｃｒを境に、１３％以下では、上限値が上昇した。熱間加工割れは、フェライト相と高温で生成するオーステナイト相との相境界で発生する頻度が高い。このことは、Ｓｎの溶解度が小さいオーステナイト相が生成することで、Ｓｎが、フェライト相側へ吐き出される過程で、オーステナイト／フェライトの結晶粒界に偏析し、粒界強度が低下しと推定される。 Ear cracks occurred as γp increased, and the upper limit increased at 13% or less with 13% Cr as a boundary. Hot work cracks frequently occur at the phase boundary between the ferrite phase and the austenite phase generated at high temperatures. This is presumed that the formation of an austenite phase with low Sn solubility causes segregation to the austenite / ferrite grain boundaries in the process of being discharged to the ferrite phase side, resulting in a decrease in grain boundary strength. .
Ｃｒ量が少ない場合、高温での変形抵抗が小さいので、γｐの上限値が上昇したと考えられる。他方、γｐが小さくなると、鋼塊の置き割れが助長される。Ｓｎは、フェライト形成元素であるとともに，接種効果により、凝固組織を微細化する元素である。そのため、従来、γｐが小さい時に発生する鋼塊の置き割れは、Ｓｎ添加による凝固組織の微細化で改善できる。 When the amount of Cr is small, the deformation resistance at high temperature is small, so it is considered that the upper limit value of γp has increased. On the other hand, when γp is reduced, the ingot is cracked. Sn is an element that refines the solidified structure due to the inoculation effect as well as a ferrite forming element. Therefore, conventionally, the cracking of the steel ingot generated when γp is small can be improved by refining the solidified structure by adding Sn.
また、Ｓｎのフェライト形成元素としての寄与は、Ｃｒとの比較で、微量添加にも拘らず大きい。本発明者らは、実験で行った組織観察から、１１００℃でのフェライト形成能は、Ｃｒの６倍と決定し、係数を「−６９（＝−１１．５×６）」と決定した。 In addition, the contribution of Sn as a ferrite-forming element is large compared with Cr despite the addition of a small amount. The present inventors determined that the ferrite forming ability at 1100 ° C. was 6 times that of Cr and the coefficient was “−69 (= −11.5 × 6)” based on the structure observation conducted in the experiment.
さらに、０．２％Ｓｎ添加鋼で冷延焼鈍板を作製し、ＳＵＳ４１０Ｌ（１２％Ｃｒ）とＳＵＳ４３０（１７％Ｃｒ）を比較材とし、ＪＩＳ Ｚ ２３７１に準拠して、３５℃、５％ＮａＣｌ水溶液による塩水噴霧試験を行い、耐銹性を評価した。評価面は、湿式ペーパー＃６００で研磨して仕上げ、噴霧時間は４８時間とした。 Furthermore, a cold-rolled annealed sheet is produced with 0.2% Sn-added steel, SUS410L (12% Cr) and SUS430 (17% Cr) are used as comparative materials, and 35 ° C., 5% NaCl according to JIS Z 2371. A salt spray test using an aqueous solution was performed to evaluate weather resistance. The evaluation surface was polished by wet paper # 600 and the spraying time was 48 hours.
ＳＵＳ４１０Ｌは、評価面で発銹し、Ｓｎ添加の１１〜１３％Ｃｒ鋼は、ＳＵＳ４３０と同様に発銹しなかった。その結果、Ｓｎ添加による耐銹性の向上効果を確認することができた。 SUS410L broke out in terms of evaluation, and the Sn-added 11-13% Cr steel did not fire as in SUS430. As a result, it was possible to confirm the effect of improving weather resistance by adding Sn.
本発明鋼板では、所要の熱間加工性を確保するため、上記式（２）で定義するγｐを、下記式（１）で限定する。
１０≦γｐ≦６５ ・・・（１）
In the steel sheet of the present invention, γp defined by the above formula (2) is limited by the following formula (1) in order to ensure the required hot workability.
10 ≦ γp ≦ 65 (1)
上記式（１）で示すように、目標とする熱間加工性は、Ｃｒが１３．０％以下の場合、γｐ６５以下で確保できる。なお、目標とする熱間加工性は、前述した熱間圧延実験で耳割れが発生しないことを意味する。 As shown in the above formula (1), the target hot workability can be secured at γp65 or less when Cr is 13.0% or less. The target hot workability means that no ear cracks occur in the hot rolling experiment described above.
熱間加工性は、γｐの低下に伴い向上する。しかし、γｐが過度に小さくなると、置き割れ感受性が高くなり、置き割れに起因する熱間加工割れが誘発される。それ故、γｐの下限は、Ｃｒ：１３．０％以下で１０とする。製造性を考慮すると、好ましい範囲は、Ｃｒ：１３．０％以下の場合、１５≦γｐ≦５５である。 Hot workability improves as γp decreases. However, when γp is excessively small, the cracking susceptibility becomes high, and hot working cracks due to the cracking are induced. Therefore, the lower limit of γp is 10 at Cr: 13.0% or less. Considering manufacturability, a preferable range is 15 ≦ γp ≦ 55 when Cr is 13.0% or less.
（III）本発明鋼板の製造方法における条件を限定する理由について説明する。 (III) The reason for limiting the conditions in the method for producing the steel sheet of the present invention will be described.
熱間圧延に供するステンレス鋼スラブの加熱温度は、熱間加工割れを誘発するオーステナイト相の生成を抑制し、熱間圧延時の変形抵抗を低下させるために１１００℃以上とする。加熱温度を過度に高くすると、結晶粒の粗大化により表面性状が劣化するし、また、加熱時のスラブ形状が悪化する恐れがあるので、上限は１３００℃とする。熱間加工性と製造性の観点から、好ましくは１１５０〜１２５０℃である。 The heating temperature of the stainless steel slab to be subjected to hot rolling is set to 1100 ° C. or higher in order to suppress the formation of an austenite phase that induces hot work cracking and to reduce deformation resistance during hot rolling. If the heating temperature is excessively high, the surface properties deteriorate due to the coarsening of crystal grains, and the slab shape during heating may deteriorate, so the upper limit is set to 1300 ° C. From the viewpoint of hot workability and manufacturability, it is preferably 1150 to 1250 ° C.
熱間圧延後の鋼板を巻き取る温度は、熱間加工性の観点から、加熱温度を高くするために７００℃以上とする。７００℃未満の場合、巻取り時の表面割れやコイルの形状不良を誘発する恐れがある。過度に巻取り温度を高くすると、内部酸化物の生成や粒界酸化を助長して、表面性状が低下するので、上限は１０００℃とする。熱間加工性と製造性の観点から、好ましくは７００〜９００℃である。 From the viewpoint of hot workability, the temperature at which the steel sheet after hot rolling is wound is 700 ° C. or higher in order to increase the heating temperature. When the temperature is lower than 700 ° C., there is a risk of inducing surface cracks during winding or a defective shape of the coil. If the coiling temperature is excessively increased, the formation of internal oxides and grain boundary oxidation are promoted, and the surface properties are lowered. Therefore, the upper limit is set to 1000 ° C. From the viewpoint of hot workability and manufacturability, the temperature is preferably 700 to 900 ° C.
熱間圧延後、焼鈍を実施するか、又は、省略して、１回の冷間圧延又は中間焼鈍を挟む２回以上の冷間圧延を実施する。熱延鋼板の焼鈍は、再結晶を促進する７００℃以上で、連続焼鈍又はバッチ式の箱焼鈍で行う。過度に焼鈍温度を高くすると、表面性状と酸洗脱スケール性の低下を招くので、上限は１０００℃とする。表面性状の観点から、好ましくは７００〜９００℃である。 After hot rolling, annealing is performed or omitted, and one or more cold rolling or two or more cold rolling sandwiching intermediate annealing are performed. Annealing of the hot-rolled steel sheet is performed by continuous annealing or batch type box annealing at 700 ° C. or higher for promoting recrystallization. If the annealing temperature is excessively increased, the surface properties and pickling descaling properties are deteriorated, so the upper limit is set to 1000 ° C. From the viewpoint of surface properties, the temperature is preferably 700 to 900 ° C.
冷間圧延後の仕上げ焼鈍は、酸化性雰囲気中又は還元性雰囲気中で行う。焼鈍温度は、再結晶、表面性状、脱スケール性を考慮すると、７００〜９００℃が好ましい。酸洗方法は特に限定するものではなく、工業的に常用されている方法でよい。例えば、アルカリソルトバス浸漬＋電解酸洗＋硝弗酸浸漬を行ってもよいし、電解酸洗は、中性塩電解や硝酸電解等を行う。 Finish annealing after cold rolling is performed in an oxidizing atmosphere or a reducing atmosphere. The annealing temperature is preferably 700 to 900 ° C. in consideration of recrystallization, surface properties, and descaling properties. The pickling method is not particularly limited, and may be a method commonly used industrially. For example, alkaline salt bath immersion + electrolytic pickling + nitrohydrofluoric acid immersion may be performed, and the electrolytic pickling performs neutral salt electrolysis or nitric acid electrolysis.
次に、本発明の実施例について説明するが、実施例での条件は、本発明の実施可能性及び効果を確認するために採用した一条件例であり、本発明は、この一条件例に限定されるものではない。本発明は、本発明の要旨を逸脱せず、本発明の目的を達成する限りにおいて、種々の条件を採用し得るものである。 Next, examples of the present invention will be described. The conditions in the examples are one example of conditions used for confirming the feasibility and effects of the present invention, and the present invention is based on this one example of conditions. It is not limited. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.
（実施例１）
表１に示す成分組成を有するフェライト系ステンレス鋼を、１５０ｋｇ、真空中で溶製し、鋼塊を１０００〜１３００℃に加熱して熱間圧延に供し、５００〜７００℃で巻き取り、板厚３．０〜６．０ｍｍの熱延鋼板を製造した。
Example 1
Ferritic stainless steel having the composition shown in Table 1 is melted in 150 kg in a vacuum, the steel ingot is heated to 1000 to 1300 ° C. and subjected to hot rolling, wound at 500 to 700 ° C., and plate thickness A 3.0 to 6.0 mm hot-rolled steel sheet was produced.
熱延鋼板に、箱焼鈍又は連続焼鈍を模擬して焼鈍を施し、又は、焼鈍を省略して、１回又は中間焼鈍を挟む２回の冷間圧延を施し、板厚０．４〜０．８ｍｍの冷延鋼板を製造した。冷延鋼板には、再結晶が完了する温度７８０〜９００℃で、仕上げ焼鈍を施した。仕上げ焼鈍は、酸化性雰囲気焼鈍又は光輝焼鈍を行った。比較鋼は、ＳＵＳ４１０Ｌ（１２Ｃｒ）、ＳＵＳ４３０（１７Ｃｒ）を使用した。 The hot-rolled steel sheet is annealed by simulating box annealing or continuous annealing, or is subjected to cold rolling twice or once with intermediate annealing, omitting the annealing, and a sheet thickness of 0.4-0. An 8 mm cold-rolled steel sheet was produced. The cold-rolled steel sheet was subjected to finish annealing at a temperature of 780 to 900 ° C. at which recrystallization was completed. In the finish annealing, oxidizing atmosphere annealing or bright annealing was performed. As comparative steels, SUS410L (12Cr) and SUS430 (17Cr) were used.
熱間加工性は、熱延板の耳割れ発生の有無を調査して評価した。耳割れが全く発生しないものを「○」、鋼板の端面から表面に及ぶ耳割れが発生したものを「×」、耳割れが鋼板表面に及ばないものを「△」とした。 The hot workability was evaluated by examining the presence or absence of the occurrence of ear cracks in the hot-rolled sheet. The case where no ear cracks occurred was indicated as “◯”, the case where ear cracks occurred from the end surface of the steel sheet to the surface was indicated as “X”, and the case where ear cracks did not reach the steel sheet surface was indicated as “Δ”.
耐銹性は、ＪＩＳ Ｚ ２３７１に準拠する塩水噴霧試験を行って評価した。試験条件は、評価面を湿式ペーパー＃６００で研磨して仕上げ、噴霧時間を４８時間とした。比較鋼の発銹程度は、ＳＵＳ４１０Ｌで“評価面から発銹”、ＳＵＳ４３０で“発銹なし”となった。そこで、評価指標は、ＳＵＳ４３０と同等の“発銹なし”を「○」とし、“発銹有り”を「×」とした。 The weather resistance was evaluated by conducting a salt spray test in accordance with JIS Z 2371. The test condition was that the evaluation surface was polished by wet paper # 600 and the spraying time was 48 hours. The degree of occurrence of the comparative steel was “no occurrence” from SUS410L and “no occurrence” from SUS430. Therefore, the evaluation index, “no occurrence” equivalent to SUS430, was set as “◯”, and “with occurrence” was set as “x”.
さらに、８０℃、０．５％ＮａＣｌ水溶液中に１６８時間浸漬する浸漬試験を行い、耐銹性を評価した。試験片は、全面を湿式ペーパー＃６００で研磨して仕上げた。比較鋼の発銹程度は、ＳＵＳ４１０Ｌで“全面発銹”と“穴あき”となり、ＳＵＳ４３０で“全面発銹”となった。そこで、評価指標は、ＳＵＳ４３０と同等の発銹を「○」とした。ＳＵＳ４１０Ｌ相当の発銹と穴あきを示したものは「×」とした。 Further, an immersion test was performed in which the sample was immersed in a 0.5% NaCl aqueous solution at 80 ° C. for 168 hours to evaluate the weather resistance. The test piece was finished by polishing the entire surface with wet paper # 600. The degree of occurrence of the comparative steel was “entire occurrence” and “perforated” with SUS410L, and “entire occurrence” with SUS430. Therefore, the evaluation index is “◯” for the occurrence equivalent to SUS430. Those showing SUS410L equivalent puncture and perforation were marked with “x”.
表２に、製造条件と試験結果をまとめて示す。 Table 2 summarizes the manufacturing conditions and test results.
表２において、試験番号１〜３、７〜２６は、本発明で規定する成分組成及びγｐと、製造条件を満足するフェライト系ステンレス鋼板に係る試験例である。これらの鋼板においては、目標とする熱間加工性と、ＳＵＳ４３０と同等の耐銹性が得られている。 In Table 2, test numbers 1 to 3 and 7 to 26 are test examples relating to the ferritic stainless steel sheet that satisfies the component composition and γp defined in the present invention and the manufacturing conditions. In these steel plates, the target hot workability and the weather resistance equivalent to SUS430 are obtained.
試験番号４〜６は、本発明で規定する成分組成及びγｐを有するが、本発明で規定する製造条件から外れるフェライト系ステンレス鋼板に係る試験例である。これらの鋼板においては、耳割れを抑止できなかったが、目標とする熱間加工性は得られている。 Test Nos. 4 to 6 are test examples relating to ferritic stainless steel sheets that have the component composition and γp specified in the present invention but deviate from the manufacturing conditions specified in the present invention. In these steel sheets, ear cracks could not be suppressed, but the target hot workability was obtained.
試験番号２７〜３２は、成分組成及びγｐが、本発明で規定する成分組成及びγｐから外れるフェライト系ステンレス鋼板に係る試験例である。これらの鋼板においては、目標とする熱間加工性と耐銹性の両方又は片方が得られていない。 Test numbers 27 to 32 are test examples relating to a ferritic stainless steel sheet in which the component composition and γp deviate from the component composition and γp defined in the present invention. In these steel sheets, the target hot workability and weather resistance or both are not obtained.
試験番号３３〜３５は、本発明で規定する成分組成を有するが、γｐが本発明で規定するγｐの範囲から外れフェライト系ステンレス鋼板に係る試験例である。これらの鋼板においては、目標とする耐銹性が得られているが、目標とする熱間加工性が得られていない。ここで、試験番号３３は、γｐが小さいため、置き割れに起因する割れが熱間加工により顕在化した試験例である。 Test Nos. 33 to 35 are test examples relating to ferritic stainless steel sheets having the component composition defined in the present invention, but γp deviating from the range of γp defined in the present invention. In these steel sheets, the target weather resistance is obtained, but the target hot workability is not obtained. Here, the test number 33 is a test example in which the crack due to the placement crack is manifested by hot working because γp is small.
試験番号３６及び３７は、それぞれ、ＳＵＳ４１０Ｌ及びＳＵＳ４３０に係る参考例である。 Test numbers 36 and 37 are reference examples according to SUS410L and SUS430, respectively.
ここで、図１に、γｐと熱間加工性の関係を示す。図１から、Ｓｎ添加鋼において良好な熱間加工性を得るためには、γｐを１０〜６５、好ましくは１５〜５５に調整する必要があることが解る。 Here, FIG. 1 shows the relationship between γp and hot workability. It can be seen from FIG. 1 that γp must be adjusted to 10 to 65, preferably 15 to 55, in order to obtain good hot workability in Sn-added steel.
本発明によれば、レアメタルの使用に頼ることなく、リサイクルした鉄源中のＳｎを有効に利用して、低Ｃｒフェライト系ステンレス鋼の耐食性を改善して、一般耐久消費材への適用が可能な省合金型のフェライト系ステンレス鋼板を提供することができる。よって、本発明は、ステンレス鋼板製造及び利用産業において利用可能性が高いものである。 According to the present invention, the corrosion resistance of low Cr ferritic stainless steel can be improved by effectively using Sn in a recycled iron source without depending on the use of rare metals, and can be applied to general durable consumer goods. An alloy-saving ferritic stainless steel sheet can be provided. Therefore, the present invention has high applicability in the production and use industries of stainless steel plates.
Claims (6)
１０≦γｐ≦６５ ・・・（１）
γｐ＝４２０Ｃ＋４７０Ｎ＋２３Ｎｉ＋７Ｍｎ＋９Ｃｕ−１１．５Ｃｒ
−１１．５Ｓｉ−５２Ａｌ−６９Ｓｎ＋１８９ ・・・（２）
ここで、Ｃ、Ｎ、Ｎｉ、Ｍｎ、Ｃｕ、Ｃｒ、Ｓｉ、Ａｌ、及び、Ｓｎは、各元素の含有量 In mass%, C: 0.001 to 0.3%, Si: 0.01 to 1.0%, Mn: 0.01 to 2.0%, P: 0.005 to 0.05%, S: 0.0001-0.01%, Cr: 11.0-13.0%, N: 0.001-0.1%, Al: 0.0001-1.0%, Sn: 0.05-1. Ferritic stainless steel sheet consisting of 0%, balance Fe and inevitable impurities, excellent in hot workability and weather resistance characterized by γp defined by the following formula (2) satisfying the following formula (1) Ferritic stainless steel sheet.
10 ≦ γp ≦ 65 (1)
γp = 420C + 470N + 23Ni + 7Mn + 9Cu-11.5Cr
-11.5Si-52Al-69Sn + 189 (2)
Here, C, N, Ni, Mn, Cu, Cr, Si, Al, and Sn are the contents of each element.
１５≦γｐ≦５５ ・・・（１’） The ferritic stainless steel sheet excellent in hot workability and weather resistance according to claim 1 , wherein the following formula (1 ′) is satisfied instead of the formula (1).
15 ≦ γp ≦ 55 (1 ′)
Priority Applications (13)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2011134224A JP5745345B2 (en) | 2011-06-16 | 2011-06-16 | Ferritic stainless steel sheet excellent in hot workability and weather resistance and manufacturing method thereof |
| BR112013032272A BR112013032272A2 (en) | 2011-06-16 | 2012-06-18 | ferritic stainless steel plate that has excellent wrinkle resistance and production method |
| CN201280029571.7A CN103608479B (en) | 2011-06-16 | 2012-06-18 | Ferrite series stainless steel plate that wrinkle resistance is excellent and manufacture method thereof |
| CN201510360013.4A CN104975237B (en) | 2011-06-16 | 2012-06-18 | The excellent ferrite series stainless steel plate of wrinkle resistance and its manufacture method |
| ES12800133T ES2788506T3 (en) | 2011-06-16 | 2012-06-18 | Ferritic stainless steel plate that has excellent scoring resistance and production method thereof |
| EP12800133.6A EP2722411B1 (en) | 2011-06-16 | 2012-06-18 | Ferritic stainless steel plate which has excellent ridging resistance and method of production of same |
| KR1020157017975A KR101688353B1 (en) | 2011-06-16 | 2012-06-18 | Ferritic stainless-steel sheet having excellent hot workability and rust resistance and process for producing same |
| PCT/JP2012/065507 WO2012173272A1 (en) | 2011-06-16 | 2012-06-18 | Ferritic stainless-steel sheet with excellent non-ridging property and process for producing same |
| KR1020137032607A KR101600156B1 (en) | 2011-06-16 | 2012-06-18 | Ferritic stainless-steel sheet with excellent non-ridging property and process for producing same |
| TW101121773A TWI480391B (en) | 2011-06-16 | 2012-06-18 | Fat iron type stainless steel plate with excellent resistance to bulking and its manufacturing method |
| US14/126,083 US9771640B2 (en) | 2011-06-16 | 2012-06-18 | Ferritic stainless steel plate which has excellent ridging resistance and method of production of same |
| US15/683,503 US10358707B2 (en) | 2011-06-16 | 2017-08-22 | Ferritic stainless steel plate which has excellent ridging resistance and method of production of same |
| US16/384,200 US10513763B2 (en) | 2011-06-16 | 2019-04-15 | Ferritic stainless steel plate which has excellent ridging resistance and method of production of same |
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| KR101712333B1 (en) * | 2013-03-25 | 2017-03-03 | 닛폰 스틸 앤드 스미킨 스테인레스 스틸 코포레이션 | Ferritic stainless steel sheet with excellent blanking workability and process for manufacturing same |
| KR101726075B1 (en) * | 2015-11-06 | 2017-04-12 | 주식회사 포스코 | Low-chromium ferritic stainless steel having excellent corrosion resistant and method for manufacturing the same |
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| JP5297713B2 (en) * | 2008-07-28 | 2013-09-25 | 新日鐵住金ステンレス株式会社 | Alloy-saving ferritic stainless steel for automobile exhaust system members with excellent corrosion resistance after heating |
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