JP2011208244A - Ferritic-austenitic stainless steel sheet to be press-formed causing small earring, and method for manufacturing the same - Google Patents
Ferritic-austenitic stainless steel sheet to be press-formed causing small earring, and method for manufacturing the same Download PDFInfo
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- 229910000963 austenitic stainless steel Inorganic materials 0.000 title claims abstract description 29
- 238000004519 manufacturing process Methods 0.000 title claims description 11
- 238000000034 method Methods 0.000 title description 13
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 23
- 239000010959 steel Substances 0.000 claims abstract description 23
- 238000005096 rolling process Methods 0.000 claims abstract description 9
- 239000012535 impurity Substances 0.000 claims abstract description 3
- 229910001566 austenite Inorganic materials 0.000 claims description 28
- 229910001220 stainless steel Inorganic materials 0.000 claims description 26
- 238000000465 moulding Methods 0.000 claims description 15
- 238000005097 cold rolling Methods 0.000 claims description 11
- 238000010438 heat treatment Methods 0.000 claims description 11
- 238000000137 annealing Methods 0.000 claims description 10
- 239000010935 stainless steel Substances 0.000 claims description 7
- 238000001953 recrystallisation Methods 0.000 claims description 4
- 230000003746 surface roughness Effects 0.000 abstract description 14
- 229910052802 copper Inorganic materials 0.000 abstract 1
- 230000007547 defect Effects 0.000 abstract 1
- 229910052759 nickel Inorganic materials 0.000 abstract 1
- 229910000859 α-Fe Inorganic materials 0.000 description 21
- 230000000694 effects Effects 0.000 description 15
- 239000000463 material Substances 0.000 description 15
- 238000005260 corrosion Methods 0.000 description 13
- 230000007797 corrosion Effects 0.000 description 13
- 238000004090 dissolution Methods 0.000 description 8
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- 238000005452 bending Methods 0.000 description 4
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- 238000007670 refining Methods 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
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- 238000009864 tensile test Methods 0.000 description 3
- 230000008033 biological extinction Effects 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 235000019589 hardness Nutrition 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 230000000087 stabilizing effect Effects 0.000 description 2
- 239000002436 steel type Substances 0.000 description 2
- 101100327917 Caenorhabditis elegans chup-1 gene Proteins 0.000 description 1
- 229910001035 Soft ferrite Inorganic materials 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 150000001447 alkali salts Chemical class 0.000 description 1
- 239000010960 cold rolled steel Substances 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
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- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 229910001039 duplex stainless steel Inorganic materials 0.000 description 1
- 230000005489 elastic deformation Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
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- 238000009533 lab test Methods 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
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- 238000009628 steelmaking Methods 0.000 description 1
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Abstract
Description
本発明は、深絞り成形加工する際に発生するイヤリングが小さく、かつ表面性状が良好な上に、材料歩留りの向上に効果的に寄与するプレス成形用フェライト・オーステナイト系ステンレス鋼板、とくに省合金型プレス成形用フェライト・オーステナイト系ステンレス冷延鋼板およびその製造方法に関するものである。 The present invention is a ferrite-austenitic stainless steel sheet for press forming, particularly an alloy-saving type, which has a small earring generated during deep drawing and has good surface properties and contributes effectively to improvement in material yield. The present invention relates to a ferrite-austenitic stainless cold-rolled steel sheet for press forming and a method for producing the same.
ステンレス鋼を大きく分類するとオーステナイト系ステンレス鋼、フェライト系ステンレス鋼、２相（フェライト・オーステナイト）系ステンレス鋼に分けられる。オーステナイト系ステンレス鋼は、Ｎｉを７％以上含有し、成形性に優れた鋼種が多い。フェライト系ステンレス鋼はＮｉをほとんど含有せず、一般的に成形性はオーステナイト系ステンレス鋼に比べてかなり低い。一方、２相（フェライト・オーステナイト）系ステンレス鋼は、これまで成形性、耐食性などにおいてオーステナイト系ステンレス鋼とフェライト系ステンレス鋼の中間的な位置づけを持つ鋼種が多い。しかし近年、フェライト・オーステナイト系ステンレス鋼においても塑性加工時のオーステナイト相の加工誘起マルテンサイト変態を活用してオーステナイト系ステンレス鋼に近い成形性を有する技術が開発されている。塑性加工分野では、成形加工は（１）深絞り加工、（２）張り出し加工、（３）伸びフランジ加工、（４）曲げ加工の４つに分類される。ここで、（１）深絞り加工は供試材を金型へ流し込みながら製品形状を得る加工方法であり、製品形状を歩留まり良く得るためには変形能の指標である伸びやｒ値の他に、フランジ残り形状の指標であるイヤリングが小さいことが重要となる。 Stainless steel can be broadly classified into austenitic stainless steel, ferritic stainless steel, and two-phase (ferrite / austenite) stainless steel. Austenitic stainless steel contains 7% or more of Ni, and many steel types are excellent in formability. Ferritic stainless steel contains little Ni and generally has a much lower formability than austenitic stainless steel. On the other hand, two-phase (ferrite / austenite) stainless steels have so far many steel types that have an intermediate position between austenitic stainless steels and ferritic stainless steels in terms of formability and corrosion resistance. However, in recent years, a technology having formability close to that of austenitic stainless steel has also been developed in ferritic / austenitic stainless steels by utilizing the work-induced martensitic transformation of the austenitic phase during plastic working. In the plastic working field, the forming process is classified into four types: (1) deep drawing, (2) overhanging, (3) stretch flange processing, and (4) bending. Here, (1) deep drawing is a processing method for obtaining a product shape while pouring a test material into a mold. In order to obtain a product shape with a good yield, in addition to elongation and r value, which are indicators of deformability, It is important that the earring, which is an indicator of the remaining flange shape, is small.
特許文献１では主相がフェライト相であり、残留オーステナイト相を含有するステンレス鋼を用いて、ＴＲＩＰ現象によって引張破断伸びを高めた技術が記載されている。特許文献２ではオーステナイト相の安定性を規定し、引張伸びを高める方法が述べられている。特許文献３においてはオーステナイト相の分率ならびにオーステナイト相中のＣ、Ｎ量を規定し、引張試験における全伸びを高める技術が示されている。また、フェライト・オーステナイト系ステンレス鋼の中には、近年の省資源化を反映しＮｉ量を低減し比較的安価なＮやＭｎでそのオーステナイト相のバランスをとり、延性と省資源化の両立を図った鋼が特許文献４に記載されている。
しかし、特許文献１では、実施例に示されるように引張破断伸びが３４〜４２％、特許文献２においては引張破断伸びが最大４６％、特許文献３では実施例で最大７１％までの破断伸び、特許文献４では引張破断伸び〜４６％が記載されているが、これら何れの文献においても実際の深絞り成形後のイヤリングに関する記述は一切見あたらず、イヤリングやそのイヤリングを生成する深絞り成形後の加工品形状との関係は不明確である。
However, in
一方、特許文献５では冷延板の連続焼鈍温度を高温化（１１５０〜１２５０℃）することにより、その後、１回の冷間圧延だけでイヤリングの小さいオーステナイト系ステンレス鋼板を製造する方法が提案されている。この方法は、冷間加工前のオーステナイト粒径を粗粒化しイヤリングを低減する方法が提案されているが、本発明のようなフェライト・オーステナイト系ステンレス鋼では、図１に示される平衡熱力学計算結果から明らかように、高温になればなるほどオーステナイト相は減少していきオーステナイト相の粗粒化は期待できない。 On the other hand, Patent Document 5 proposes a method of manufacturing an austenitic stainless steel sheet having small earrings by only one cold rolling after increasing the continuous annealing temperature of the cold rolled sheet (1150 to 1250 ° C.). ing. In this method, a method for reducing the earrings by coarsening the austenite grain size before cold working has been proposed, but in the ferrite-austenitic stainless steel as in the present invention, the equilibrium thermodynamic calculation shown in FIG. As is clear from the results, the austenite phase decreases as the temperature increases, and coarsening of the austenite phase cannot be expected.
従来技術では、引張試験における伸びが高くても実際の絞り成形が主であるプレス加工でイヤリグが大きく歩留まり落ちが顕著となる問題があった。一般的なプレス成形に対して、フェライト・オーステナイト系ステンレス鋼を広く活用していくためには材料設計指針や材料特性を明確化することが必要である。本発明者らは、特に二相鋼のプレス成形時に求められる材料流入挙動を均一とする方法を明確化することが重要と考えた。 In the prior art, even if the elongation in the tensile test is high, there has been a problem that the yield is large and the yield drop becomes noticeable in the press working mainly in the actual drawing. In order to widely use ferritic and austenitic stainless steels for general press forming, it is necessary to clarify material design guidelines and material characteristics. The inventors of the present invention have considered that it is important to clarify a method for making the material inflow behavior that is particularly required at the time of press forming of a duplex stainless steel.
上記のような課題に鑑み、本発明ではイヤリングの小さいプレス成形用フェライト・オーステナイト系ステンレス鋼板およびその製造方法を提供することが目的である。 In view of the above problems, an object of the present invention is to provide a press-forming ferrite-austenitic stainless steel sheet having a small earring and a method for producing the same.
本発明者らは、従来技術における上記課題を解決し、フェライト・オーステナイト系ステンレス鋼板のイヤリングを低減させるため、フェライト・オーステナイト系ステンレス鋼の成分組成に基づき、ミクロ組織、引張特性および表面性状の影響をラボ試験により鋭意検討を重ねた。その結果、イヤリングが小さくすることが可能なミクロ組織、引張特性、表面粗さ、成分の組み合わせがあることを見出し、本発明を完成した。 In order to solve the above-mentioned problems in the prior art and reduce the earrings of ferritic / austenitic stainless steel sheets, the inventors of the present invention are based on the composition of the ferritic / austenitic stainless steels, and the effects of microstructure, tensile properties and surface properties Intensively studied through lab tests. As a result, the inventors found that there is a combination of microstructure, tensile properties, surface roughness, and components that can make the earrings small, and completed the present invention.
本発明の要旨は、次の通りである。 The gist of the present invention is as follows.
（１） 圧延方向に対して０°方向と９０°方向の０．２％耐力の差が２０ＭＰａ未満、圧延方向と９０°方向の鋼板表面の粗さＲｚが０．５〜４μｍであり、かつ、下記（１）式で示されるイヤリング率が２％未満であることを特徴とするイヤリングの小さいプレス成形用フェライト・オーステナイト系ステンレス鋼板。
イヤリング率（％）＝２×（ｈｍａｘ−ｈｍｉｎ）／（ｈｍａｘ＋ｈｍｉｎ）×１００ ・・・ （１）
上記式中でｈｍａｘ：深絞りカップの底から山までの高さ、ｈｍｉｎ：深絞りカップの底から谷までの高さを意味する。
(1) The difference in 0.2% proof stress between the 0 ° direction and the 90 ° direction with respect to the rolling direction is less than 20 MPa, the roughness Rz of the steel sheet surface in the rolling direction and the 90 ° direction is 0.5 to 4 μm, and A ferritic / austenitic stainless steel sheet for press molding with a small earring, wherein the earring rate represented by the following formula (1) is less than 2%.
Earring rate (%) = 2 × (hmax−hmin) / (hmax + hmin) × 100 (1)
In the above formula, hmax: the height from the bottom of the deep drawn cup to the mountain, hmin: the height from the bottom of the deep drawn cup to the valley.
（２） 質量％で、
Ｃ：０．０１〜０．０４％、
Ｓｉ：１．０％以下、
Ｍｎ：４．０．〜６．０％、
Ｐ：０．０５％以下、
Ｓ：０．０１０％以下、
Ｎｉ：１．０〜２．０％、
Ｃｒ：２０．０〜２２．０％、
Ｃｕ：０．１〜１．０％、
Ａｌ：０．０１〜０．０６％、
Ｎ：０．１５〜０．２５％
を含有し、残部がＦｅおよび不可避的不純物からなることを特徴とする上記（１）記載のイヤリングの小さいプレス成形用フェライト・オーステナイト系ステンレス鋼板。
(2) By mass%
C: 0.01-0.04%
Si: 1.0% or less,
Mn: 4.0. ~ 6.0%,
P: 0.05% or less,
S: 0.010% or less,
Ni: 1.0-2.0%,
Cr: 20.0-22.0%,
Cu: 0.1 to 1.0%
Al: 0.01 to 0.06%,
N: 0.15-0.25%
Ferrite and austenitic stainless steel sheet for press molding with a small earring according to (1) above, wherein the balance is Fe and the inevitable impurities.
（３） さらに、質量％で、
Ｍｏ：０．１〜１．０％
Ｎｂ：０．０３〜０．５０％、
Ｔｉ：０．０３〜０．５０％、
の１種または２種以上を含有することを特徴とする上記（１）または（２）記載のイヤリングの小さいプレス成形用フェライト・オーステナイト系ステンレス鋼板。
(3) Furthermore, in mass%,
Mo: 0.1 to 1.0%
Nb: 0.03-0.50%,
Ti: 0.03-0.50%,
The ferritic / austenitic stainless steel sheet for press molding with a small earring according to the above (1) or (2), characterized by containing one or more of the above.
（４） さらに、質量％で、
Ｃａ：０．０００５〜０．００３０％、
Ｍｇ：０．０００５〜０．００３０％、
Ｂ：０．０００５〜０．００３０％
の１種または２種以上を含有することを特徴とする上記（１）乃至（３）の内のいずれか１項に記載のイヤリングの小さいプレス成形用フェライト・オーステナイト系ステンレス鋼板。
(4) Furthermore, in mass%,
Ca: 0.0005 to 0.0030%,
Mg: 0.0005 to 0.0030%,
B: 0.0005 to 0.0030%
The ferrite-austenitic stainless steel sheet for press molding with a small earring according to any one of the above (1) to (3), characterized by containing one or more of the above.
（５） 上記（２）乃至（４）の内のいずれか１項に記載の鋼成分を有するステンレス鋼からなる熱延板を１１００〜１１５０℃、焼鈍時間５〜６０秒で焼鈍し、次いで合計冷延率６３％以上で冷間圧延し、その後、再結晶熱処理を施すことを特徴とするイヤリングの小さいプレス成形用フェライト・オーステナイト系ステンレス鋼板の製造方法。 (5) A hot-rolled sheet made of stainless steel having the steel component described in any one of (2) to (4) above is annealed at 1100 to 1150 ° C. for an annealing time of 5 to 60 seconds, and then totaled A method for producing a ferrite austenitic stainless steel sheet for press molding with a small earring, characterized by performing cold rolling at a cold rolling rate of 63% or more and then performing a recrystallization heat treatment.
以下の説明で、上記（１）〜（５）の鋼板に係わる発明をそれぞれ本発明という。また、（１）〜（５）の発明を合わせて、本発明ということがある。 In the following description, the inventions related to the steel plates (1) to (5) are referred to as the present invention. The inventions (1) to (5) may be collectively referred to as the present invention.
本発明によれば、高価かつ稀少な元素であるＮｉを多量に含有することなくイヤリングの小さいフェライト・オーステナイト系ステンレス鋼を製造できるため、資源保護ならびに環境保全に貢献しうるものと考えられる。 According to the present invention, ferrite and austenitic stainless steel with small earrings can be produced without containing a large amount of expensive and rare element Ni, and it is considered that it can contribute to resource protection and environmental conservation.
以下、本発明を詳細に説明する。 Hereinafter, the present invention will be described in detail.
まず、本発明の重要な要素であるイヤリング率に及ぼす表面粗さＲｚと０．２％耐力の異方性の関係について説明する。 First, the relationship between the surface roughness Rz and the 0.2% proof stress anisotropy on the earring rate, which is an important element of the present invention, will be described.
［圧延方向に対して０°方向と９０°方向の０．２％耐力の差が２０ＭＰａ未満、圧延方向と９０°方向の鋼板表面の粗さＲｚが０．５〜４μｍ、イヤリング率が２％未満］：深絞り加工時の材料流入に着目すると、材料の変形は金型Ｄｉｅ Ｒ部の曲げ→曲げ戻し変形から開始される。すなわち、曲げ変形が、方向を問わず均一に変形していくことが重要である。０．２％耐力は弾性変形から塑性変形へ変わる指標の１つであることから、この差が顕著となれば変形し易い部分と変形し難い部分が生じる。変形し易い部分は流入量が多く、変形し難い部分は流入量が少なくなり、絞り加工でこの差が助長されるため、イヤリングを発生する原因の１つになる。一般的にはオーステナイト系ステンレス鋼のような単相鋼のイヤリング生成要因は、結晶方位の集積度やすべり系として考えられているが、フェライト・オーステナイト系ステンレス鋼では、存在する２相ですべり系は異なり、しかも、それぞれの相が分離して分布していることから、単相組織の考え方を用いてイヤリング率を低減することは不可能であることが明白である。 [The difference in 0.2% proof stress between the 0 ° direction and the 90 ° direction with respect to the rolling direction is less than 20 MPa, the roughness Rz of the steel sheet surface in the rolling direction and the 90 ° direction is 0.5 to 4 μm, and the earring rate is 2%. Less than]: Focusing on the material inflow during deep drawing, the deformation of the material is started from the bending of the die Die R portion to the bending back deformation. That is, it is important that the bending deformation is uniformly deformed regardless of the direction. Since the 0.2% proof stress is one of the indices that change from elastic deformation to plastic deformation, if this difference becomes significant, a portion that is easily deformed and a portion that is difficult to deform are generated. A portion that is easily deformed has a large inflow amount, and a portion that is difficult to deform has a small amount of inflow, and this difference is promoted by drawing, which is one of the causes of the occurrence of earrings. In general, the cause of earring formation in single-phase steels such as austenitic stainless steel is considered to be the degree of crystal orientation accumulation and the slip system, but in ferrite and austenitic stainless steel, the existing two-phase slip system is considered. However, since the phases are separated and distributed, it is apparent that it is impossible to reduce the earring rate using the concept of single-phase structure.
したがって、フェライト・オーステナイト系ステンレス鋼においては、円筒深絞り成形時の材料の流入抵抗を均一とすること、すなわち、０．２％耐力の各方向における差を小さくすることがイヤリング率を低下させることにつながるため、０．２％耐力の異方性差を調査した結果、２０ＭＰａ未満でイヤリング率が２％未満となることが明確になった。好ましくは、１０ＭＰａ以下である。ここで、イヤリング率は低ければ低いほど良いことが明白であるが、２％未満であれば顕著なイヤリングとは認識できないことから上限を２％未満とした。
イヤリング率は下記（１）式で表すことができる。
イヤリング率（％）＝２×（ｈｍａｘ−ｈｍｉｎ）／（ｈｍａｘ＋ｈｍｉｎ）×１００ ・・・ （１）
上記式中でｈｍａｘ：深絞りカップの底から山までの高さ、ｈｍｉｎ：深絞りカップの底から谷までの高さを意味する。
Therefore, in ferrite-austenitic stainless steel, making the inflow resistance of the material uniform during deep drawing of the cylinder, that is, reducing the difference in each direction of 0.2% proof stress lowers the earring rate. As a result of investigating the anisotropy difference of 0.2% proof stress, it became clear that the earring rate was less than 2% at less than 20 MPa. Preferably, it is 10 MPa or less. Here, it is apparent that the lower the earring rate, the better. However, if it is less than 2%, it cannot be recognized as a prominent earring, so the upper limit was made less than 2%.
The earring rate can be expressed by the following equation (1).
Earring rate (%) = 2 × (hmax−hmin) / (hmax + hmin) × 100 (1)
In the above formula, hmax: the height from the bottom of the deep drawn cup to the mountain, hmin: the height from the bottom of the deep drawn cup to the valley.
すなわち、図２のイヤリング率算出の基本となるｈｍａｘとｈｍｉｎを説明する図に示すように、供試材を金型へ流し込みながら製品形状を得る深絞り加工をした際に、ｈｍａｘは深絞りカップ１の底２から山３までの高さ、ｈｍｉｎは深絞りカップ１の底２から谷４までの高さである。
That is, as shown in the figure explaining hmax and hmin which are the basis for calculating the earring rate in FIG. 2, when deep drawing processing is performed to obtain a product shape while pouring the test material into the mold, hmax is a deep drawing cup. 1 is the height from the bottom 2 to the
さらに、鋼板表面の粗さにより材料流入は大きく影響される。ステンレス鋼板をプレス成形する際には、多くの場合潤滑油を用いる。これは、鋼板が金型へ焼き付き易い特性を有しているためであり、焼き付きによる製品歩留まりの低下や金型摩耗を抑制して、生産性を確保する狙いがある。したがって、潤滑油が成型過程で鋼板と金型の境界に存在していることが重要となる。 Furthermore, material inflow is greatly influenced by the roughness of the steel plate surface. When press forming a stainless steel plate, lubricating oil is often used. This is because the steel sheet has the characteristic of being easily seized onto the mold, and has an aim of ensuring productivity by suppressing the decrease in product yield and mold wear due to seizure. Therefore, it is important that the lubricating oil is present at the boundary between the steel plate and the mold during the molding process.
潤滑油が鋼板もしくは金型表面に存在していても、成形時に金型に鋼板表面が強く押し付けられ、鋼板表面を擦りながら移動していくため、同時に潤滑油の存在スペースが失われてしまう。ここで、フェライト・オーステナイト系ステンレス鋼では、二相が存在するため最終デスケール時に溶解量が異なるため、単相のフェライト系ステンレス鋼やオーステナイト系ステンレス鋼とは異なった各相に対応する表面の凹凸が発現する。また、この二相は硬さが異なるため、成形過程での変形量が異なる。すなわち、適度な表面粗さにより潤滑油が鋼板表面に存在し易い凹凸が形成され、成形過程でこの凹凸が維持されながら変形していくため、プレス過程で高い潤滑性能が発揮されプレス成形性が高くなることが明確になった。 Even if the lubricating oil is present on the surface of the steel plate or the mold, the surface of the steel plate is strongly pressed against the mold at the time of molding and moves while rubbing the surface of the steel plate. Here, since ferrite and austenitic stainless steels have two phases, the amount of dissolution differs at the time of final descaling, so surface irregularities corresponding to each phase differ from single-phase ferritic stainless steels and austenitic stainless steels. Is expressed. In addition, since the two phases have different hardnesses, the amount of deformation in the molding process differs. In other words, unevenness where lubricating oil is likely to be present on the surface of the steel sheet is formed with an appropriate surface roughness, and deformation occurs while maintaining the unevenness in the forming process, so that high lubrication performance is exhibited in the pressing process and press formability is improved. It became clear that it would be higher.
図３は表面粗さＲｚと均一伸びの関係に限界絞り比を重ねた図である。Ｒｚが０．５未満では、潤滑油を捕捉する凹凸が充分ではなく、４．０μｍを超えると凹凸が大きすぎるため、凹部に潤滑油が存在するのみで凸部頂上には潤滑油が殆ど存在せず、鋼板と金型が接触するため著しい成形性低下を招く。したがって、Ｒｚを０．５〜４μｍとしたが、好ましくは、Ｒｚが１．０〜３．０μｍの範囲である。 FIG. 3 is a diagram in which the limit drawing ratio is superimposed on the relationship between the surface roughness Rz and the uniform elongation. If the Rz is less than 0.5, the unevenness for capturing the lubricating oil is not sufficient, and if it exceeds 4.0 μm, the unevenness is too large. However, since the steel plate and the mold are in contact with each other, a significant decrease in formability is caused. Therefore, although Rz was set to 0.5 to 4 μm, Rz is preferably in the range of 1.0 to 3.0 μm.
以下に成分の限定理由を述べる。なお、以下に示す「％」とは質量％を表す。 The reasons for limiting the components are described below. In addition, "%" shown below represents mass%.
Ｃ：Ｃはオーステナイト相の安定度に大きな影響を及ぼす元素であるとともにＣｒ炭化物の析出を促進するために粒界腐食の発生をもたらす耐食性には有害な元素である。耐食性の点からＣは低くするほうが好ましいが、低減するためには精錬時のコスト増加を招く。したがって、０．０１〜０．０４％の範囲とした。好ましくは、０．０２５〜０．０４％の範囲である。 C: C is an element having a great influence on the stability of the austenite phase and an element harmful to the corrosion resistance that causes the occurrence of intergranular corrosion to promote the precipitation of Cr carbide. Although it is preferable to lower C from the point of corrosion resistance, in order to reduce it, the cost at the time of refining is increased. Therefore, it was set as 0.01 to 0.04% of range. Preferably, it is 0.025 to 0.04% of range.
Ｓｉ：Ｓｉは脱酸元素として使われたり、耐酸化性向上のために含有されたりする場合がある。しかし、材料の硬質化をもたらし、均一伸びが低下するため、１．０％を上限とした。またＳｉを極低減するためには精錬時のコスト増加を招く。好ましくは、０．０５〜１．０％の範囲であり、さらに好ましくは、０．４〜１．０％の範囲である。 Si: Si may be used as a deoxidizing element or may be contained for improving oxidation resistance. However, the material is hardened and the uniform elongation is lowered, so 1.0% was made the upper limit. Moreover, in order to reduce Si extremely, the cost at the time of refining is increased. Preferably, it is in the range of 0.05 to 1.0%, and more preferably in the range of 0.4 to 1.0%.
Ｍｎ：Ｍｎはオーステナイト相に濃化し、オーステナイト相の安定度を変化させるのに重要な役割を持つ。特に、高価なＮｉと類似の効果を発現できることから、下限を４．０％とした。しかし多量の含有は耐食性や熱間加工性の低下をもたらすため、上限を６．０％とした。好ましくは４．５〜５．５％とすることが望ましい。 Mn: Mn concentrates in the austenite phase and plays an important role in changing the stability of the austenite phase. In particular, an effect similar to that of expensive Ni can be exhibited, so the lower limit was made 4.0%. However, since a large amount causes a decrease in corrosion resistance and hot workability, the upper limit was made 6.0%. Preferably it is 4.5 to 5.5%.
Ｐ：Ｐは不可避的に混入する元素であり、またＣｒなどの原料に含有されているため、低減することが困難であるが、多量に含有した場合には成形性を低下させるため、上限を０．０５０％とした。 P: P is an element inevitably mixed in, and since it is contained in raw materials such as Cr, it is difficult to reduce it. However, if it is contained in a large amount, the formability is lowered, so the upper limit is set. 0.050%.
Ｓ：Ｓは不可避的に混入する元素であり、Ｍｎと結合して介在物をつくり、発銹の基点となる場合があるため、上限を０．０１０％とした。低いほど耐食性からは好ましいため、０．００３％以下とすることが望ましい。 S: S is an element inevitably mixed in, and may combine with Mn to form inclusions, which may serve as the starting point of the cracking, so the upper limit was made 0.010%. Since it is preferable from the viewpoint of corrosion resistance, the lower the content, the lower the content is preferably 0.003% or less.
Ｃｒ：Ｃｒは耐食性を確保するために必要であるとともにＮの固溶限を上昇させる元素であるため、２０．０％以上の含有が必要である。しかし、多量の含有は熱間加工割れを原因となり、精錬工程のコスト増加につながるため、上限を２２．０％とした。好ましくは、２０．０〜２１．０％の範囲である。 Cr: Cr is an element that is necessary for ensuring the corrosion resistance and increases the solid solubility limit of N, and therefore needs to be contained in an amount of 20.0% or more. However, since a large amount causes hot working cracks and leads to an increase in the cost of the refining process, the upper limit was made 22.0%. Preferably, it is in the range of 20.0 to 21.0%.
Ｎｉ：Ｎｉはオーステナイト安定化元素であり、オーステナイト相の安定度を調整するために重要な元素である。また熱間加工割れを抑制する効果を持つため、１．０％以上含有させる。２．０％を超える含有は、原料コストの増加をもたらし、またオーステナイト、フェライトの２相組織を得ることが困難になる場合があるため、これを上限とした。好ましくは、１．２〜１．７％の範囲である。 Ni: Ni is an austenite stabilizing element and is an important element for adjusting the stability of the austenite phase. Moreover, in order to have an effect which suppresses a hot work crack, 1.0% or more is contained. If the content exceeds 2.0%, the raw material cost increases, and it may be difficult to obtain a two-phase structure of austenite and ferrite. Preferably, it is 1.2 to 1.7% of range.
Ｎ：ＮはＣ同様にオーステナイト相の安定度に大きな影響を及ぼす元素である。また固溶して存在した場合に耐食性を向上させる効果を持つため、０．１５％以上含有することとする。但し、０．２５％以上含有した場合は硬度の上昇が著しくなり、均一伸びが低下する場合が認められるほか、Ｃｒ窒化物が析出しやすくなって逆に耐食性の低下をもたらすため、これを上限とした。好ましくは、０．１８〜０．２２％の範囲である。 N: N, like C, is an element that greatly affects the stability of the austenite phase. Moreover, since it has the effect of improving corrosion resistance when it exists in solid solution, it shall contain 0.15% or more. However, when it is contained in an amount of 0.25% or more, the hardness is remarkably increased and the uniform elongation may be decreased. In addition, Cr nitride is likely to precipitate, and conversely, the corrosion resistance is decreased. It was. Preferably, it is 0.18 to 0.22% of range.
Ａｌ：Ａｌは鋼の脱酸能力が非常に大きい元素であり、フェライト相の靱性向上の観点から必ず添加する必要がある。脱酸により酸化物系介在物を減少させ高い靱性を得るためには０．０１％以上の含有が必要である。一方過剰な添加は鋼の硬質化を招き、加工性を低下させる可能性があるので０．０６％以下の含有量とする。好ましくは、０．０２〜０．０５％の範囲である。 Al: Al is an element having a very large deoxidizing ability of steel, and must be added from the viewpoint of improving the toughness of the ferrite phase. In order to reduce oxide inclusions by deoxidation and obtain high toughness, a content of 0.01% or more is necessary. On the other hand, excessive addition leads to hardening of the steel and may deteriorate the workability, so the content is made 0.06% or less. Preferably, it is 0.02 to 0.05% of range.
Ｃｕ：ＣｕもＮｉ同様、オーステナイト安定化元素であり、オーステナイト相の安定度を調整するために重要な元素である。ただし、１．０％を超える含有は熱間加工時の割れを促進し、また強度を上昇させるため、これを上限とした。安定して効果を得るためには、０．１％以上が好ましい。 Cu: Cu, like Ni, is an austenite stabilizing element and is an important element for adjusting the stability of the austenite phase. However, if the content exceeds 1.0%, cracking during hot working is promoted and the strength is increased, so this was made the upper limit. In order to obtain an effect stably, 0.1% or more is preferable.
また、選択的に下記元素を含有することができる。 Moreover, the following elements can be selectively contained.
Ｍｏ：Ｍｏは耐食性を向上させる元素であるため、選択的に含有しても良い。０．１％以上の含有により、耐食性向上効果が発揮される。安定して効果を得るためには、０．５％以上が好ましい。ただし、１．０％を超えると均一伸びが低下し深絞り性を低下させるとともに、原料コストが大きく増加するため、これを上限とした。 Mo: Since Mo is an element that improves corrosion resistance, it may be selectively contained. By containing 0.1% or more, the corrosion resistance improving effect is exhibited. In order to obtain an effect stably, 0.5% or more is preferable. However, if it exceeds 1.0%, the uniform elongation is lowered, the deep drawability is lowered, and the raw material cost is greatly increased.
Ｎｂ：Ｎｂは溶接熱影響部の粗大化を防止する効果があるが、０．５０％超の含有は均一伸びを低下させるため、これを上限とした。安定して効果を得るためには、０．０３％以上が望ましい。 Nb: Nb has the effect of preventing the weld heat-affected zone from becoming coarse, but the content exceeding 0.50% lowers the uniform elongation, so this was made the upper limit. In order to obtain an effect stably, 0.03% or more is desirable.
Ｔｉ：ＴｉもＮｂ同様、溶接熱影響部の粗大化を防止する効果を有する。さらには凝固組織を微細等軸晶化するため、０．０３％以上の含有が好ましい。ただし、０．５０％超の含有は均一伸びを低下させるため、これを上限とした。 Ti: Ti, as well as Nb, has the effect of preventing the weld heat affected zone from becoming coarse. Furthermore, the content is preferably 0.03% or more in order to finely equiax the solidified structure. However, the content exceeding 0.50% lowers the uniform elongation, so this was made the upper limit.
Ｃａ：Ｃａは脱硫、脱酸のために若干含有されることがある。但し、０．００３０％超の含有によって熱間加工割れが生じやすくなり、また耐食性が低下するため、これを上限とした。安定して効果を得るためには、０．０００５％以上が望ましい。 Ca: Ca may be slightly contained for desulfurization and deoxidation. However, hot work cracking tends to occur when the content exceeds 0.0030%, and the corrosion resistance decreases, so this was made the upper limit. In order to obtain the effect stably, 0.0005% or more is desirable.
Ｍｇ：Ｍｇは、脱酸だけでなく、凝固組織を微細化する効果を持つ。これらの効果を安定して発揮するためには、０．０００５％以上の含有が望ましい。また、０．００３０％超の含有は製鋼工程でのコスト増加をもたらすため、これを上限とした。 Mg: Mg has not only deoxidation but also an effect of refining the solidified structure. In order to stably exhibit these effects, the content is preferably 0.0005% or more. Moreover, since content exceeding 0.0030% brings about the cost increase in a steelmaking process, this was made into the upper limit.
Ｂ：Ｂは粒界強度を上昇させるのに有効な元素である。このような効果を安定して発揮するためには、０．０００５％以上の含有が望ましい。また、０．００３０％超の含有は多量のホウ化物生成を招き、耐食性を著しく低下させる。 B: B is an element effective for increasing the grain boundary strength. In order to stably exhibit such an effect, the content is preferably 0.0005% or more. Further, if the content exceeds 0.0030%, a large amount of boride is formed, and the corrosion resistance is remarkably lowered.
次に、製造方法についての限定理由を述べる。 Next, the reasons for limiting the manufacturing method will be described.
図１は本発明鋼の代表組成（０．０１％Ｃ−０．１％Ｓｉ−５％Ｍｎ−１．５％Ｎｉ−２１％Ｃｒ−０．５％Ｃｕ−０．２％Ｎ）を用いて、サーモカルクｖｅｒ．Ｑによって算出したフェライト・オーステナイト系ステンレス鋼の９００℃〜１２００℃におけるフェライト相率を示す図である。１１００℃でフェライト相率５７％、１２００℃でフェライト相率７７％と温度が上昇するに従いフェライト相率は増加している。１１００℃以上の温度ではフェライト相率がオーステナイトよりも多く存在すると推定される。オーステナイト相の比率が低下することで、ファイバー状に存在するオーステナイト相を分断することが可能となる。したがって、熱処理温度は１１００℃以上とした。しかし、１１５０℃以上の温度では、オーステナイト相が部分的に消失するためフェライト相の粒成長が著しくなり、破断強度の低下による成形性の劣化を招くことが明らかとなったため、上限を１１５０℃とした。次いで、熱処理時間では、高Ｎ含有である効果から組織形成はＮの拡散によって律速される（特に高温では組織変化が急激に起こる）ため、焼鈍時間を６０秒までとした。一方、Ｎの拡散にともなう組織形成が安定するためには保定時間が必要であることから、５秒以上の焼鈍時間とした。ここで、冷延板焼鈍に供する素材の冷間圧延率が低い場合には、軟質なフェライト相に冷間圧延の歪が集中して導入されるため、オーステナイト相への歪導入が少なくなるため組織変化が生じ難く、冷間圧延前に存在する粗大粒が部分的に残存してしまう。したがって、６３％以上の合計冷延率が必要となる。好ましくは、板厚が１．５ｍｍ以下で７０％以上の合計冷延率によって、鋼板を製造することである。冷延板への再結晶熱処理は、再結晶温度が高いオーステナイト相の温度や時間に律速されるが、熱処理温度が高すぎたり、熱処理時間が長すぎるとフェライト相の粒成長が促進されるため、１０００〜１１００℃で３０秒以内が望ましい。 FIG. 1 uses the representative composition of the steel of the present invention (0.01% C-0.1% Si-5% Mn-1.5% Ni-21% Cr-0.5% Cu-0.2% N). Thermocalc ver. It is a figure which shows the ferrite phase rate in 900 to 1200 degreeC of the ferrite austenitic stainless steel computed by Q. The ferrite phase rate increases as the temperature rises to 57% ferrite phase rate at 1100 ° C. and 77% ferrite phase rate at 1200 ° C. It is presumed that at a temperature of 1100 ° C. or higher, the ferrite phase ratio is larger than that of austenite. By reducing the ratio of the austenite phase, it becomes possible to divide the austenite phase present in a fiber shape. Therefore, the heat treatment temperature is set to 1100 ° C. or higher. However, at a temperature of 1150 ° C. or higher, the austenite phase partially disappears, so that the grain growth of the ferrite phase becomes remarkable, and it becomes clear that the moldability is deteriorated due to the decrease in breaking strength. did. Next, in the heat treatment time, the structure formation is rate-determined by the diffusion of N due to the effect of high N content (particularly, the structure change rapidly occurs at high temperatures), so the annealing time was set to 60 seconds. On the other hand, in order to stabilize the formation of the structure accompanying the diffusion of N, a holding time is required, so an annealing time of 5 seconds or longer was set. Here, when the cold rolling rate of the material subjected to cold rolled sheet annealing is low, the strain of cold rolling is concentrated and introduced into the soft ferrite phase, so that the introduction of strain into the austenite phase is reduced. It is difficult for the structure to change, and the coarse grains existing before cold rolling partially remain. Therefore, a total cold rolling rate of 63% or more is required. Preferably, the steel sheet is manufactured with a total cold rolling rate of 70% or more when the plate thickness is 1.5 mm or less. Recrystallization heat treatment on cold-rolled plates is rate-controlled by the temperature and time of the austenite phase, which has a high recrystallization temperature, but if the heat treatment temperature is too high or the heat treatment time is too long, grain growth of the ferrite phase is promoted. , 1000-1100 ° C., preferably within 30 seconds.
表１に示す化学組成の鋼を真空高周波溶解炉により、厚さ５０ｍｍ、幅１６０ｍｍ幅の鋳塊とし、１２００℃に加熱した後に、熱間圧延により５ｍｍ厚の熱延板とした。その後、表２に示す条件で熱延板焼鈍の後、デスケール、冷間圧延の工程を経て、種々の厚さの冷延板を製造した。これら冷延板に焼鈍温度：１０５０℃、焼鈍時間：１５秒の冷延板焼鈍を実施した。得られた冷延焼鈍板のデスケールは、アルカリソルト浴（４３０℃３０秒保定）によるスケール改質処理の後にＨＦ／ＨＮＯ３溶液を用いたデスケールにより供試材とした。ここで、ＨＦ／ＨＮＯ３の条件は、ＨＦ＝５〜５０ｇ／Ｌ、ＨＮＯ３＝２０〜１００ｇ／Ｌで変化させ、溶液温度を５０℃、浸漬時間を２０秒で固定することで、表面粗さを変化させた。溶解量が少なければ、スケール残りや各相における溶解量の差が小さくなるため表面が平坦であり、溶解量が多すぎれば、各相の溶解量の差が大きくなるため、凹凸が顕在化し、表面粗さが著しく大きくなった。表面粗さは、各相比率の影響を受けやすいが、ＨＦ：ＨＮＯ３の比率を１：５〜２：５とすると表面粗さが最適範囲内に入る。 Steel having the chemical composition shown in Table 1 was made into an ingot having a thickness of 50 mm and a width of 160 mm in a vacuum high-frequency melting furnace, heated to 1200 ° C., and then hot-rolled to a thickness of 5 mm. Then, after hot-rolled sheet annealing under the conditions shown in Table 2, cold-rolled sheets with various thicknesses were manufactured through the steps of descaling and cold rolling. These cold-rolled sheets were subjected to cold-rolled sheet annealing at an annealing temperature of 1050 ° C. and an annealing time of 15 seconds. The obtained cold-rolled annealed plate was descaled as a test material by descaling using an HF / HNO 3 solution after a scale reforming treatment with an alkali salt bath (430 ° C., 30 seconds hold). Here, the conditions of HF / HNO 3 were changed at HF = 5 to 50 g / L, HNO 3 = 20 to 100 g / L, the solution temperature was fixed at 50 ° C., and the immersion time was fixed at 20 seconds. Changed. If the amount of dissolution is small, the difference in the amount of dissolution in the remaining scale and each phase is small, the surface is flat, and if the amount of dissolution is too large, the difference in the amount of dissolution of each phase becomes large, and the unevenness becomes obvious, The surface roughness was significantly increased. The surface roughness is easily affected by the ratio of each phase. However, when the ratio of HF: HNO 3 is 1: 5 to 2: 5, the surface roughness falls within the optimum range.
供試材の表面粗さ測定は、ミツヨト製ＳＶ３０００ＣＮＣ３次元粗さ計（触針径：２μｍ）を用い、ＪＩＳＢ０６０１’０１に準拠した条件で高さ倍率２０００倍として圧延方向に対して９０°方向のＲｚを３回実施し平均を求めた。０．２％耐力測定のための引張試験は、圧延方向に対して０°と９０°方向から採取したＪＩＳ１３号Ｂ試験片により、ＪＩＳに準拠した条件で２回測定し平均値を求めた。イヤリング率の測定はエリクセン社製１４２／４０型薄板成形試験機を用い、Ｐｕｎｃｈ径４０ｍｍ、Ｄｉｅ径４３ｍｍの金型を用い、試験片径８０ｍｍ（絞り比２．０：試験片径／Ｐｕｎｃｈ径）の円筒深絞りを実施し、成形加工品の山高さと谷高さを測定し算出した。深絞り試験の成形条件は、クッション圧１ｔｏｎ、潤滑剤は＃１２２ワックスとした。 The surface roughness of the test material was measured using a Mitutoyo SV3000 CNC three-dimensional roughness meter (stylus diameter: 2 μm), with a height magnification of 2000 times under the conditions in accordance with JISB0601'01. Rz was performed 3 times and the average was calculated. In the tensile test for measuring 0.2% proof stress, an average value was obtained by measuring twice with JIS No. 13 B specimens taken from 0 ° and 90 ° directions with respect to the rolling direction under the conditions conforming to JIS. The earring rate is measured using a 142/40 type thin plate molding tester manufactured by Eriksen, using a mold with a punch diameter of 40 mm and a die diameter of 43 mm, and a test piece diameter of 80 mm (drawing ratio 2.0: test piece diameter / Punch diameter). The cylindrical deep drawing was carried out, and the peak height and valley height of the molded product were measured and calculated. The molding conditions for the deep drawing test were 1 ton cushion pressure and # 122 wax as the lubricant.
熱間圧延材に施した製造条件および得られた鋼板を用いて調査した表面粗さＲｚ、０．２％耐力およびイヤリング率を表２に示す。 Table 2 shows the manufacturing conditions applied to the hot-rolled material and the surface roughness Rz, 0.2% proof stress and earring rate investigated using the obtained steel plate.
表２から明らかなように成分範囲（Ｎｏ．１〜１５）、表面粗さＲｚおよび製造条件が本発明範囲を満足する場合（Ｎｏ．２−２、３−２、６−２、９−２、１０−２、１５−２を除く）に、イヤリング率は２％未満となっている。Ｎｏ．１６〜Ｎｏ．２５は、成分が範囲外であり、本発明の製造条件を満たしていたとしてもＮｏ．２３、Ｎｏ．２４に示されるように、０．２％耐力の異方性もしくは表面粗さが外れているため、イヤリング率が２％超となっている。Ｎｏ．２−２のように成分範囲は満足しているものの熱処理温度が上限を外れているため、フェライト相の著しい粒成長に起因したミクロ組織の不均一が生じた結果、０．２％耐力の異方性差が大きくなるとともにデスケール時の各相の溶解量に差が生じ、イヤリング率は２％超となっている。同様にＮｏ．３−２のように成分範囲は満足しているものの熱処理温度が下限を外れているため、オーステナイト相の拡散消滅に不均一が生じた結果、０．２％耐力の異方性差が大きくなりイヤリング率は２％超となっている。また、Ｎｏ．６−２では成分範囲、製造条件は満足しているもののデスケール時の溶解量の差が大きくなったため、表面粗さが本発明範囲から外れており、イヤリング率が３．１％と２％超となっている。Ｎｏ．９−２は、冷延率が５０％と低く熱延板組織の分断が不十分なため、０．２％耐力の異方性が大きくなりイヤリング率が２％超となっている。Ｎｏ．１０−２は成分範囲を満しているが、熱処理時間が短時間側で外れているため、オーステナイト相の拡散消滅が充分に達成されずミクロ組織の不均一さが生じてしまい、０．２％耐力の異方性差が大きくなるとともにデスケール時の各相の溶解量に差が生じ、イヤリング率は２％超となっている。Ｎｏ．１５−２は熱処理時間が長時間に外れており、フェライト相の粒成長が生じたためオーステナイト相の拡散減少が進み、０．２％耐力の異方性が大きくなっている。
本発明により、イヤリングの小さいプレス成形性に優れたフェライト・オーステナイト系ステンレス鋼を得ることが可能となる。
As apparent from Table 2, the component ranges (No. 1 to 15), the surface roughness Rz, and the production conditions satisfy the scope of the present invention (No. 2-2, 3-2, 6-2, 9-2). 10-2 and 15-2), the earring rate is less than 2%. No. 16-No. No. 25 is out of the range, even if the production conditions of the present invention were satisfied, No. 25. 23, no. As shown in FIG. 24, since the anisotropy or surface roughness of 0.2% proof stress is removed, the earring rate is over 2%. No. As shown in 2-2, although the component range is satisfactory, the heat treatment temperature is outside the upper limit, resulting in non-uniformity of the microstructure due to remarkable grain growth of the ferrite phase. As the difference in directionality increases, the amount of dissolution of each phase at the time of descaling varies, and the earring rate is over 2%. Similarly, no. Although the component range is satisfactory as in 3-2, the heat treatment temperature is outside the lower limit, and as a result, nonuniformity occurs in the diffusion and extinction of the austenite phase, resulting in a large 0.2% proof stress anisotropy difference. The rate is over 2%. No. In 6-2, although the component range and production conditions were satisfied, the difference in the amount of dissolution at the time of descaling was large, so the surface roughness was out of the scope of the present invention, and the earring rate was 3.1%, exceeding 2%. It has become. No. In 9-2, the cold rolling rate is as low as 50% and the hot-rolled sheet structure is not sufficiently divided, so the anisotropy of 0.2% proof stress is increased and the earring rate is over 2%. No. 10-2 satisfies the component range, but since the heat treatment time is out on the short time side, the diffusion and extinction of the austenite phase is not sufficiently achieved, resulting in non-uniform microstructure, and 0.2 The anisotropy difference in% proof stress increases and the amount of dissolution of each phase at the time of descaling varies, and the earring rate is over 2%. No. No. 15-2 has a long heat treatment time, and the ferrite phase grain growth has occurred, so that the diffusion reduction of the austenite phase has progressed, and the 0.2% yield strength anisotropy has increased.
According to the present invention, it is possible to obtain a ferritic / austenitic stainless steel having small earrings and excellent press formability.
１ 深絞りカップ
２ 底
３ 山
４ 谷
1 Deep drawn
Claims (5)
イヤリング率（％）＝２×（ｈｍａｘ−ｈｍｉｎ）／（ｈｍａｘ＋ｈｍｉｎ）×１００ ・・・ （１）
上記式中でｈｍａｘ：深絞りカップの底から山までの高さ、ｈｍｉｎ：深絞りカップの底から谷までの高さを意味する。 The difference in 0.2% proof stress between the 0 ° direction and the 90 ° direction with respect to the rolling direction is less than 20 MPa, the roughness Rz of the steel sheet surface in the rolling direction and the 90 ° direction is 0.5 to 4 μm, and the following ( 1) A ferrite-austenitic stainless steel plate for press molding having a small earring, wherein the earring rate represented by the formula is less than 2%.
Earring rate (%) = 2 × (hmax−hmin) / (hmax + hmin) × 100 (1)
In the above formula, hmax: the height from the bottom of the deep drawn cup to the mountain, hmin: the height from the bottom of the deep drawn cup to the valley.
Ｃ：０．０１〜０．０４％、
Ｓｉ：１．０％以下、
Ｍｎ：４．０〜６．０％、
Ｐ：０．０５０％以下、
Ｓ：０．０１０％以下、
Ｎｉ：１．０〜２．０％、
Ｃｒ：２０．０〜２２．０％、
Ｃｕ：０．１〜１．０％、
Ａｌ：０．０１〜０．０６％、
Ｎ：０．１５〜０．２５％
を含有し、残部がＦｅおよび不可避的不純物からなることを特徴とする請求項１記載のイヤリングの小さいプレス成形用フェライト・オーステナイト系ステンレス鋼板。 % By mass
C: 0.01-0.04%
Si: 1.0% or less,
Mn: 4.0 to 6.0%,
P: 0.050% or less,
S: 0.010% or less,
Ni: 1.0-2.0%,
Cr: 20.0-22.0%,
Cu: 0.1 to 1.0%
Al: 0.01 to 0.06%,
N: 0.15-0.25%
The ferritic / austenite stainless steel sheet for press molding with a small earring according to claim 1, wherein the balance comprises Fe and inevitable impurities.
Ｍｏ：０．１〜１．０％
Ｎｂ：０．０３〜０．５０％、
Ｔｉ：０．０３〜０．５０％、
の１種または２種以上を含有することを特徴とする請求項１または２記載のイヤリングの小さいプレス成形用フェライト・オーステナイト系ステンレス鋼板。 Furthermore, in mass%,
Mo: 0.1 to 1.0%
Nb: 0.03-0.50%,
Ti: 0.03-0.50%,
The ferritic / austenitic stainless steel sheet for press molding with a small earring according to claim 1 or 2, wherein the ferritic / austenitic stainless steel sheet is small.
Ｃａ：０．０００５〜０．００３０％、
Ｍｇ：０．０００５〜０．００３０％、
Ｂ：０．０００５〜０．００３０％
の１種または２種以上を含有することを特徴とする請求項１乃至３の内のいずれか１項に記載のイヤリングの小さいプレス成形用フェライト・オーステナイト系ステンレス鋼板。 Furthermore, in mass%,
Ca: 0.0005 to 0.0030%,
Mg: 0.0005 to 0.0030%,
B: 0.0005 to 0.0030%
The ferrite-austenitic stainless steel sheet for press molding having a small earring according to any one of claims 1 to 3, wherein the ferritic austenitic stainless steel sheet is small.
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