JPH11350081A - Corrosion resistant steel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively provide a corrosion resisting steel having excellent corrosion resistance in various corrosive environments, such as an atmospheric corrosion environment, a city water corrosion environment, a soil corrosion environment, a concrete corrosion environment, a seawater corrosion environment, and a drinking water corrosion environment, including a high temperature wet corrosion environment, e.g. exhaust system of internal combustion engine of automobile, etc., and a dew condensation corrosion environment. SOLUTION: A steel, which has a composition containing, by weight, 0.01-3.0% Si, 0.01-3.0% Mn, 10-30% Cr, and 0.1-3.0% Al, also containing C, P, S, and N in the amounts reduced to <=0.02%, <=0.03%, <=0.01%, and <=0.02%, respectively, desirably within the range satisfying C+N<=0.03%, and having the balance Fe with inevitable impurities and further containing, desirably, one or more elements among Cu, Mo, Sb, Ni, W, rare earth elements, and Ca and further containing, desirably, 0.01-1.0%, each, of Nb, V, Ti, Zr, Ta, and Hf so that their total amount satisfies a limiting equation, is used as a base material, and the surface of this base material is coated with a metal having an electric potential, in an aqueous solution environment, baser than that of the base material to 0.5-500 μm thickness.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は、耐食鋼に係り、更
に詳しくは、例えば、（１）自動車や船舶等の内燃機関
排気系統、ボイラ排気系統、低温熱交換機、焼却炉床等
の高温湿潤腐食環境、（２）橋梁、支柱、建築内外装
材、屋根材、建具、厨房部材、各種手すり、ガードレー
ル、各種フック、ルーフドレイン、鉄道車両等の大気腐
食環境、（３）各種貯蔵タンク、支柱、杭、矢板等の土
壌腐食環境、（４）缶容器、各種容器、低温熱交換機、
浴室部材、自動車構造部材等の結露腐食環境（冷凍、湿
潤、乾燥が複合する腐食環境を含む）、（５）貯水槽、
給水管、給湯管、缶容器、各種容器、食器、調理機器、
浴槽、プール、洗面化粧台等の水道水腐食環境、（６）
缶容器、各種容器、食器、調理機器等の飲料水腐食環
境、（７）各種鉄筋構造物、支柱等のコンクリート腐食
環境、（８）船舶、橋梁、杭、矢板、海洋構造物等の海
水腐食環境等の、種々の腐食環境において優れた耐食性
を有する耐食鋼に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to corrosion-resistant steel, and more specifically, for example, to (1) high-temperature wetness of an exhaust system of an internal combustion engine of a car or a ship, a boiler exhaust system, a low-temperature heat exchanger, an incinerator floor, and the like. Corrosive environment, (2) bridges, columns, building interior and exterior materials, roofing materials, fittings, kitchen members, various handrails, guardrails, various hooks, roof drains, atmospheric corrosion environments such as railway vehicles, (3) various storage tanks, columns , Piles, sheet piles, etc., soil corrosion environment, (4) can containers, various containers, low-temperature heat exchangers,
Dew condensation corrosive environment (including corrosive environment where freezing, humidification and drying are combined) of bathroom members, automobile structural members, etc., (5) water storage tank,
Water supply pipe, hot water supply pipe, can container, various containers, tableware, cooking equipment,
Corrosion environment of tap water such as bathtub, pool, vanity, etc. (6)
Corrosion environment of drinking water for canned containers, various containers, tableware, cooking equipment, etc., (7) Corrosion environment for concrete such as various reinforced structures and columns, (8) Seawater corrosion for ships, bridges, piles, sheet piles, marine structures, etc. The present invention relates to a corrosion-resistant steel having excellent corrosion resistance in various corrosive environments such as environments.

【０００２】[0002]

【従来の技術】従来、自動車を中心とする内燃機関の排
気系統には、内面あるいは外面からの腐食を抑制するた
めに普通鋼にアルミニウムメッキや亜鉛メッキを施した
鋼が使用されてきた。環境汚染を抑制するために排気ガ
ス浄化の目的で触媒等が排気系統に具備されたためにこ
うしたメッキ鋼材では耐食性が充分ではなくなり、鋼素
地の耐食性向上を目的として５〜１０％のＣｒを含有さ
せた鋼が、特開昭６３−１４３２４０号公報や特開昭６
３−１４３２４１号公報で開示されている。しかし、近
年の車両の使用期間および保証期間の延長に伴なって、
更にＣｒを１８％程度まで含有させ、あるいは更にＭｏ
を添加した高級ステンレス鋼が排気系統に多く使用され
ている。2. Description of the Related Art Conventionally, in an exhaust system of an internal combustion engine mainly for an automobile, steel in which ordinary steel is plated with aluminum or zinc to suppress corrosion from the inside or outside has been used. Since a catalyst or the like is provided in the exhaust system for the purpose of purifying exhaust gas to suppress environmental pollution, such a plated steel material does not have sufficient corrosion resistance, and contains 5 to 10% Cr for the purpose of improving the corrosion resistance of the steel base. Steel is disclosed in JP-A-63-143240 and JP-A-6-143240.
It is disclosed in JP-A-3-143241. However, with the extension of the service period and warranty period of vehicles in recent years,
Further, Cr is contained up to about 18%, or
The high-grade stainless steel to which is added is widely used in exhaust systems.

【０００３】しかし、このような高級ステンレス鋼であ
っても孔食状の局部腐食が発生する場合があるなど、耐
食性は必ずしも充分ではない。また、こうした高級ステ
ンレス鋼はＣｒやＭｏを多量に含有するために加工性が
悪く、排気系部材のような複雑な形状を形成するために
は、製造に非常な困難を伴い、製造工程が著しく複雑に
なるために加工コストも高くなるという難点がある。か
つ、素材コストも高い。[0003] However, even such a high-grade stainless steel does not always have sufficient corrosion resistance, for example, pitting-like local corrosion may occur. In addition, such high-grade stainless steel has poor workability because it contains a large amount of Cr and Mo, and in order to form a complicated shape such as an exhaust system member, production is extremely difficult, and the production process is extremely difficult. There is a disadvantage that the processing cost increases due to the complexity. Also, the material cost is high.

【０００４】上記の排気系統を代表として、一般にＣｒ
をある程度含有する鋼では使用腐食環境が厳しくなると
局部腐食が発生し易く、これに対する手段として腐食に
対する抵抗を向上させるためには、更にＣｒあるいはＭ
ｏの含有量を増加させるのが極めて一般的な技術的手段
であった。また、ＣｒおよびＭｏを用いて耐食性を保有
させる場合、排気ガス環境に対しては充分な耐食性を有
する場合でも、米国やカナダの寒冷地のように、冬季に
道路路面の凍結を防止する目的で多量の塩を散布する場
合には、かかる塩分によって外面から排気系部材が侵食
されることも問題となっている。[0004] As a representative of the above exhaust system, Cr
In steels containing a certain amount of iron, local corrosion is likely to occur when the use corrosion environment becomes severe. In order to improve resistance to corrosion as a measure against this, Cr or M
Increasing the content of o has been a very common technical measure. When Cr and Mo are used to maintain corrosion resistance, even if they have sufficient corrosion resistance to the exhaust gas environment, they can be used to prevent freezing of road surfaces in winter, such as in the cold regions of the United States and Canada. When spraying a large amount of salt, there is a problem that the exhaust system member is eroded from the outer surface by the salt.

【０００５】近年、特開平５−２７９７９１号公報、特
開平６−１７９９４９号公報、特開平６−１７９９５０
号公報、特開平６−１７９９５１号公報、特開平６−２
１２２５６号公報、特開平６−２１２２５７号公報、特
開平７−３３８８号公報において、耐食性の向上あるい
は耐食性と加工性の向上を目的としたＣｒにＡｌを添加
した鋼が開示されている。これらの鋼は、排気系内面耐
食性あるいは排気系内面耐食性と加工性の向上にはある
程度有効と認められるが、塩害耐食性を中心とする湿潤
耐食性に関しては改善の余地を残しているのが現状であ
る。In recent years, Japanese Patent Application Laid-Open Nos. Hei 5-279791, Hei 6-179949, Hei 6-179950
JP, JP-A-6-179951, JP-A-6-2
JP-A-12256, JP-A-6-212257 and JP-A-7-3388 disclose steels in which Al is added to Cr for the purpose of improving corrosion resistance or improving corrosion resistance and workability. Although these steels are recognized to be effective to some extent in improving the exhaust system inner corrosion resistance or the exhaust system inner surface corrosion resistance and workability, there is still room for improvement in wet corrosion resistance, especially salt corrosion resistance. .

【０００６】[0006]

【発明が解決しようとする課題】本発明は、こうした現
状に鑑みて、内燃機関の排気系統をはじめとする高温湿
潤腐食環境、結露腐食環境、更には大気腐食環境、水道
水腐食環境、土壌腐食環境、コンクリート腐食環境、海
水腐食環境、飲料水腐食環境等の様々な腐食環境におけ
る耐食性の優れた低コストの耐食鋼を提供することを目
的としている。SUMMARY OF THE INVENTION In view of these circumstances, the present invention provides a high-temperature wet corrosion environment including an exhaust system of an internal combustion engine, a condensation corrosion environment, an atmospheric corrosion environment, a tap water corrosion environment, and a soil corrosion. It is an object of the present invention to provide a low-cost corrosion-resistant steel having excellent corrosion resistance in various corrosive environments such as an environment, a concrete corrosive environment, a seawater corrosive environment, and a drinking water corrosive environment.

【０００７】[0007]

【課題を解決するための手段】本発明者らは上記の目的
を達成すべく、内燃機関の排気系統をはじめとする高温
湿潤腐食環境、結露腐食環境、更には大気腐食環境、水
道水腐食環境、土壌腐食環境、コンクリート腐食環境、
海水腐食環境、飲料水腐食環境等の様々な腐食環境にお
いて優れた耐食性を有する鋼を開発するべく、種々の観
点から検討してきた。Means for Solving the Problems In order to achieve the above object, the present inventors have set a high temperature wet corrosion environment including an exhaust system of an internal combustion engine, a dew condensation corrosion environment, an atmospheric corrosion environment, and a tap water corrosion environment. , Soil corrosion environment, concrete corrosion environment,
In order to develop a steel having excellent corrosion resistance in various corrosive environments such as a seawater corrosive environment and a drinking water corrosive environment, studies have been made from various viewpoints.

【０００８】まず、本発明者らは最も腐食に対して厳し
い排気系統の内面腐食環境について検討し、内燃機関排
気系統の腐食は排気ガス中に含まれる塩化物、硫酸イオ
ン等が８０〜１５０℃に加熱された環境において起こる
ことを見出した。更に、該腐食環境において耐食性を向
上させる手段を種々検討した結果、Ａｌを０．１〜３．
０％添加したＣｒを１０〜３０％含む鋼が排気系統をは
じめとする腐食環境で非常に優れた耐食性を示すことを
見出した。First, the present inventors examined the internal corrosion environment of the exhaust system, which is the most susceptible to corrosion. Found to occur in a heated environment. Furthermore, as a result of variously examining means for improving the corrosion resistance in the corrosive environment, it was found that Al was 0.1 to 3.
It has been found that steel containing 10% to 30% of Cr added with 0% exhibits extremely excellent corrosion resistance in a corrosive environment such as an exhaust system.

【０００９】更に本発明者らはより優れた鋼にせんとし
て検討を続けた結果、Ｃｒを１０〜３０％、Ａｌを０．
１〜３．０％含有する鋼のＣおよびＮを低減した上でＮ
ｂ，Ｖ，Ｔｉ，Ｚｒ，Ｔａ，Ｈｆを特定の条件を満足す
るように添加すると、耐食性の改善と加工性の向上に効
果があること、脱酸および強化元素としてはＳｉおよび
Ｍｎが適切であること、上記の鋼にＣｕ，Ｍｏ，Ｓｂ，
Ｎｉ，Ｗを単独あるいは組み合わせて添加するとより優
れた耐食性が得られることを見出した。Further, the present inventors have continued to study the use of more excellent steel, and as a result, have found that Cr has a content of 10 to 30% and Al has a content of 0.1%.
After reducing C and N of steel containing 1 to 3.0%, N
When b, V, Ti, Zr, Ta, and Hf are added so as to satisfy specific conditions, it is effective in improving corrosion resistance and workability, and Si and Mn are suitable as deoxidizing and strengthening elements. That is, Cu, Mo, Sb,
It has been found that more excellent corrosion resistance can be obtained by adding Ni or W alone or in combination.

【００１０】一方で本発明者らは、排気系統の内面腐食
環境に次ぐ厳しい腐食環境である塩害腐食や塩水等の乾
湿繰り返しに対する腐食抵抗を高めた鋼材を得る手段に
ついても別途並行して検討した結果、Ｃｒを１０〜３０
％含有し、Ａｌを０．１％以上含有する鋼を基材とし
て、その表面に、水溶液環境における電位が基材よりも
卑なる金属の被覆層を形成すると、優れた耐食性、特に
優れた耐塩害腐食性が得られることを見い出した。On the other hand, the present inventors separately studied in parallel the means for obtaining a steel material having enhanced corrosion resistance against salt damage corrosion, which is a severe corrosive environment next to the exhaust gas inner surface corrosive environment, and repeated wet and dry conditions such as salt water. As a result, Cr was 10-30.
% Of a steel containing 0.1% or more of Al as a base material, when a coating layer of a metal whose potential in an aqueous solution environment is lower than that of the base material is formed on the surface thereof, excellent corrosion resistance, particularly excellent resistance It has been found that salt corrosion is obtained.

【００１１】特にＡｌの添加は、基材表面に被覆した電
位が基材よりも卑なる金属の層が部分的に消失し、ごく
わずかに基材表面が腐食環境に露出した後の耐食性向上
に効果が顕著であることを見出した。このＡｌの基材中
への添加による耐食性向上挙動は、上述した基材の耐食
性とは全く異なる現象であり、基材表面に被覆した電位
が基材よりも卑なる金属の層が存在し、かつ、この金属
層が部分的に消失したときに初めて認められる現象であ
ることを確認している。In particular, the addition of Al improves the corrosion resistance after the metal layer coated on the surface of the substrate and having a potential lower than that of the substrate partially disappears and the surface of the substrate is slightly exposed to a corrosive environment. The effect was found to be remarkable. The behavior of improving the corrosion resistance by adding Al into the substrate is a phenomenon completely different from the corrosion resistance of the substrate described above, and there is a metal layer in which the potential coated on the substrate surface is lower than the substrate, In addition, it has been confirmed that this phenomenon is observed only when the metal layer partially disappears.

【００１２】見出した著しい耐食性向上の理由には現状
では不明点が多いが、基材にＡｌを添加することで、基
材表面が腐食環境に露出した後の残存する基材表面に被
覆した、電位が基材よりも卑なる金属の層の消失速度が
著しく低下し、従って基材表面の腐食環境に露出される
面積の拡大速度が著しく低下し、同時に、露出した基材
部分に対する基材表面に被覆した電位が基材よりも卑な
る金属の層の基材露出部分に対する保護作用が長期にわ
たって継続することによって、耐食性が向上しているこ
とを確認している。At present, there are many unknown reasons for the remarkable improvement in corrosion resistance found, but by adding Al to the substrate, the surface of the substrate was coated on the remaining substrate surface after being exposed to the corrosive environment. The rate of disappearance of the layer of metal whose potential is lower than that of the substrate is significantly reduced, and thus the rate of expansion of the area of the substrate surface exposed to the corrosive environment is significantly reduced, and at the same time, the surface of the substrate relative to the exposed substrate portion It has been confirmed that the corrosion resistance is improved by protecting the exposed portion of the base material of the metal layer whose potential is lower than that of the base material over a long period of time.

【００１３】このような効果が認められる基材表面の腐
食環境への露出部分は顕微鏡観察で初めて確認できるも
ので、絶対値では約０．０５mm² 程度以下の微小面積
で、全腐食面積に対する比率では０．２％以下のわずか
なものであり、実使用を想定した巨視的な肉眼外観上は
全く赤錆の発生がないことはもとより、一般的には基材
の腐食が認められないと判断される外観を呈している。
しかもこのような状態が長期間維持されることが特徴で
ある。The exposed portion of the substrate surface to the corrosive environment where such an effect is recognized can be confirmed for the first time by microscopic observation, and has a small area of about 0.05 mm ² or less in absolute value and a ratio to the total corroded area. Is less than 0.2%, and it is judged that there is no occurrence of red rust at all on the macroscopic appearance assuming actual use, and that generally no corrosion of the substrate is observed. It has an external appearance.
Moreover, it is a feature that such a state is maintained for a long time.

【００１４】従来の知見では、基材表面に被覆した電位
が基材よりも卑なる金属の層が存在し、かつ、この金属
層が部分的に消失したときには、表面に被覆した金属層
の腐食速度は基材金属の腐食を抑制するために増大し、
従って基材金属の腐食環境への露出面積は急速に拡大
し、速やかに基材金属の腐食に移行すると考えるのが一
般的であることを考えると、基材金属中へのＡｌの添加
による上述した耐食性向上は、従来全く知られていなか
った本願発明の根本となる耐食性向上手段であり、本願
発明はこのような新たな発見に基づいてなされたもので
ある。According to conventional knowledge, when a metal layer coated on the surface of a base material has a potential lower than that of the base material, and when this metal layer partially disappears, corrosion of the metal layer coated on the surface is caused. The speed is increased to control the corrosion of the base metal,
Therefore, considering that it is generally considered that the exposed area of the base metal to the corrosive environment rapidly expands, and that it is generally considered that the base metal quickly shifts to the corrosion of the base metal. The improvement of the corrosion resistance is a means of improving the corrosion resistance, which has not been known at all, and is the basis of the present invention, and the present invention has been made based on such a new discovery.

【００１５】本発明者らは、基材表面に被覆した電位が
基材よりも卑なる金属の層が存在する基材金属中へのＡ
ｌの添加による耐食性向上効果を更に高めるための手段
について種々検討を重ね、基材へのＳｉ，Ｍｎ，Ｔｉ，
Ｚｒ，Ｔａ，Ｈｆ，Ｃｕ，Ｍｏ，Ｓｂ，Ｎｉ，Ｗの添加
が有効であること、基材耐食性と加工性の向上に効果が
認められたＮｂ，Ｖは耐食性向上効果を阻害しないこと
を明らかにした。The inventors of the present invention have proposed that A is added to a base metal in which a metal layer having a potential lower than that of the base coated on the surface of the base exists.
Various studies have been made on means for further increasing the corrosion resistance improving effect by the addition of l, and Si, Mn, Ti,
It is clear that the addition of Zr, Ta, Hf, Cu, Mo, Sb, Ni, and W is effective, and that Nb and V, which are effective in improving the base material corrosion resistance and workability, do not inhibit the corrosion resistance improvement effect. I made it.

【００１６】更に、本発明者らは検討を続け、水溶液環
境における電位が基材よりも卑なる金属として、アルミ
ニウム、アルミニウムを主体とする合金、亜鉛、亜鉛を
主体とする合金、クロム、クロムを主体とする合金、マ
ンガン、マンガンを主体とする合金、が本発明の目的に
適する金属であることをも見出した。本発明は主に上記
の知見に基づいてなされたものであり、本願第１発明の
要旨は、重量％で、Ｓｉ：０．０１〜３．０％、Ｍｎ：
０．０１〜３．０％、Ｃｒ：１０〜３０％、Ａｌ：０．
１〜３％、残部Ｆｅおよび不可避的不純物からなり、該
不可避的不純物のうちＣを０．０２％以下、Ｐを０．０
３％以下、Ｓを０．０１％以下、Ｎを０．０２％以下に
制限した鋼を基材として、該基材表面に、水溶液環境に
おける電位が基材よりも卑なる金属の被覆層を０．０５
〜５００μｍ厚さに形成したことを特徴とする耐食鋼に
ある。Further, the present inventors have continued their studies and have found that aluminum, an alloy mainly composed of aluminum, zinc, an alloy mainly composed of zinc, chromium, and chromium are metals whose electric potential in an aqueous solution environment is lower than that of a substrate. It has also been found that an alloy mainly composed of manganese and an alloy mainly composed of manganese are metals suitable for the purpose of the present invention. The present invention has been mainly made based on the above findings, and the gist of the first invention of the present application is that, by weight%, Si: 0.01 to 3.0%, Mn:
0.01-3.0%, Cr: 10-30%, Al: 0.
1 to 3%, with the balance being Fe and unavoidable impurities, of which C is 0.02% or less and P is 0.0
3% or less, 0.01% or less of S and 0.02% or less of N are used as a base material, and a metal coating layer whose electric potential in an aqueous solution environment is lower than that of the base material is provided on the surface of the base material. 0.05
Corrosion resistant steel characterized in that it is formed to a thickness of up to 500 μm.

【００１７】第２発明の要旨は、第１発明の鋼におい
て、基材が付加成分として更に、重量％で、Ｃｕ：０．
０１〜５．０％、Ｍｏ：０．０５〜１０％、Ｓｂ：０．
０１〜０．５％、Ｎｉ：０．０１〜１０％、Ｗ：０．０
５〜３．０％、の１種または２種以上を含有することを
特徴とする耐食鋼にある。The gist of the second invention is that, in the steel of the first invention, the base material further contains Cu: 0.
01-5.0%, Mo: 0.05-10%, Sb: 0.
01 to 0.5%, Ni: 0.01 to 10%, W: 0.0
Corrosion resistant steel containing one or more of 5 to 3.0%.

【００１８】第３発明の要旨は、第１発明、第２発明の
鋼において、基材が付加成分として更に、重量％で、希
土類元素：０．００１〜０．１％，Ｃａ：０．０００１
〜０．０５％の１種または２種以上を含有することを特
徴とする耐食鋼にある。第４発明の要旨は、第１発明、
第２発明、第３発明の鋼において、基材が付加成分とし
て更に、重量％で、Ｎｂ，Ｖ，Ｔｉ，Ｚｒ，Ｔａ，Ｈｆ
の中から選ばれる１種あるいは２種以上の元素を単独含
有量で０．０１〜１％含有し、かつ次式を満足すること
を特徴とする耐食鋼にある。The gist of the third invention is that, in the steels of the first and second inventions, the base material is further added as an additional component by weight, rare earth element: 0.001 to 0.1%, Ca: 0.0001.
Corrosion-resistant steel characterized by containing one or more of 0.05% or more. The gist of the fourth invention is the first invention,
In the steels of the second and third inventions, the base material may further contain Nb, V, Ti, Zr, Ta, and Hf by weight as an additional component.
A corrosion-resistant steel comprising one or more elements selected from the group consisting of 0.01 to 1% in terms of a single content, and satisfying the following expression.

【００１９】Ｎｂ／９３＋Ｖ／５１＋Ｔｉ／４８＋Ｚｒ
／９１＋Ｔａ／１８１≧０．８×（Ｃ／１２＋Ｎ／１
４） 第５発明の要旨は、第１発明、第２発明、第３発明、第
４発明において、被覆層の金属が、アルミニウムあるい
はアルミニウムを主体とする合金のいずれかである耐食
鋼にある。Nb / 93 + V / 51 + Ti / 48 + Zr
/91+Ta/181≧0.8×(C/12+N/1
4) The gist of the fifth invention lies in the corrosion-resistant steel according to the first, second, third and fourth inventions, wherein the metal of the coating layer is either aluminum or an alloy mainly composed of aluminum.

【００２０】第６発明の要旨は、第１発明、第２発明、
第３発明、第４発明において、被覆層の金属が、亜鉛あ
るいは亜鉛を主体とする合金のいずれかである耐食鋼に
ある。第７発明の要旨は、第１発明、第２発明、第３発
明、第４発明において、被覆層の金属が、クロムあるい
はクロムを主体とする合金のいずれかである耐食鋼にあ
る。The gist of the sixth invention is that the first invention, the second invention,
In the third invention and the fourth invention, there is provided the corrosion-resistant steel in which the metal of the coating layer is either zinc or an alloy mainly containing zinc. The gist of the seventh invention resides in the corrosion-resistant steel according to the first, second, third, and fourth inventions, wherein the metal of the coating layer is either chromium or an alloy mainly composed of chromium.

【００２１】第８発明の要旨は、第１発明、第２発明、
第３発明、第４発明において、被覆層の金属が、マンガ
ンあるいはマンガンを主体とする合金のいずれかである
耐食鋼にある。The gist of the eighth invention is that the first invention, the second invention,
In the third invention and the fourth invention, there is provided the corrosion-resistant steel in which the metal of the coating layer is either manganese or an alloy mainly containing manganese.

【００２２】[0022]

【発明の実施の形態】以下に本発明において、基材の各
成分の範囲を限定した理由を述べる。 Ｓｉ： Ｓｉは、Ｃｒを１０％以上含有する鋼に脱酸剤
および強化元素としての添加が有効であるが、含有量が
０．０１％未満ではその脱酸効果が充分ではなく、３％
を超えて含有するともはやその効果は飽和している上に
加工性を低下させるので、含有量範囲を０．０１％以上
３％以下に限定する。更にＳｉを添加することで基材表
面に、水溶液環境における電位が基材よりも卑なる金属
の層を０．０５〜５００μｍ厚さに形成せしめた場合の
耐食性を向上する効果をもたらすが、０．０１５％未満
では効果が認められず、１．５％を超えて添加してもそ
の効果が飽和する。従って、０．０１５％以上１．５％
以下の範囲で添加することがより望ましい。BEST MODE FOR CARRYING OUT THE INVENTION The reasons for limiting the range of each component of a substrate in the present invention will be described below. Si: The addition of Si as a deoxidizing agent and a strengthening element to steel containing 10% or more of Cr is effective. However, if the content is less than 0.01%, the deoxidizing effect is not sufficient, and 3%
If the content exceeds 0.1%, the effect is no longer saturated and the processability is reduced. Therefore, the content range is limited to 0.01% or more and 3% or less. Furthermore, the addition of Si brings about the effect of improving the corrosion resistance when a metal layer having a potential lower than that of the base material in an aqueous solution environment is formed to a thickness of 0.05 to 500 μm on the base material surface. If the content is less than 0.015%, no effect is observed, and even if added over 1.5%, the effect is saturated. Therefore, 0.015% or more and 1.5%
It is more desirable to add in the following range.

【００２３】Ｍｎ： Ｍｎは、鋼の脱酸剤として必要
で、０．０１％以上を含有させる必要があるが、３．０
％を超えて含有させてもその効果はもはや飽和している
ばかりか、過剰にＭｎを含有させると加工性が低下する
ので、上限含有量は３．０％とする。さらにＭｎを添加
することで、基材表面に水溶液環境における電位が基材
よりも卑なる金属の層を０．５〜５００μｍ厚さに形成
せしめた場合に耐食性を向上する効果をもたらすが、
０．０５％未満では効果が認められず、１．２％を超え
て添加してもその効果が飽和する。従って、０．０５％
以上１．２％以下の範囲で添加することがより望まし
い。Mn: Mn is required as a deoxidizing agent for steel and needs to be contained in an amount of 0.01% or more.
%, The effect is not only saturated anymore, but if Mn is excessively contained, the workability is reduced. Therefore, the upper limit content is set to 3.0%. By further adding Mn, the potential in an aqueous solution environment on the base material surface has an effect of improving corrosion resistance when a metal layer whose base is lower than that of the base material is formed to a thickness of 0.5 to 500 μm,
If less than 0.05%, no effect is observed, and even if added over 1.2%, the effect is saturated. Therefore, 0.05%
More preferably, it is added in the range of at least 1.2%.

【００２４】Ｃｒ： Ｃｒは、排気ガス環境等に対する
基材単体での耐食性を確保するためにＡｌを０．１５％
以上含有する鋼に１０％以上を含有させることが必要で
あるが、３０％を超えて含有させても加工性が低下する
ので、上限含有量は３０％とする。さらにＡｌを０．１
５％以上含有する鋼にＣｒを添加することで、基材表面
に水溶液環境における電位が基材よりも卑なる金属の層
を０．５〜５００μｍ厚さに形成せしめた場合に耐食性
を向上する効果をもたらすが、２５％を超えて添加して
もその効果が飽和する。従って、１０％以上２５％以下
の範囲で添加することがより望ましい。Cr: Cr is 0.15% in order to secure the corrosion resistance of the substrate alone against the exhaust gas environment and the like.
It is necessary that the steel contained above contains 10% or more. However, if the content exceeds 30%, the workability decreases, so the upper limit content is set to 30%. Further, 0.1
By adding Cr to steel containing 5% or more, corrosion resistance is improved when a metal layer whose electric potential in an aqueous environment is lower than that of the base material is formed to a thickness of 0.5 to 500 μm on the base material surface. The effect is obtained, but the effect is saturated even if added in excess of 25%. Therefore, it is more desirable to add in the range of 10% or more and 25% or less.

【００２５】Ａｌ： Ａｌは、本発明において耐食性を
確保するために最も重要な元素であって、Ｃｒを１０％
以上含有する鋼Ａｌを添加することで、基材表面に水溶
液環境における電位が基材よりも卑なる金属の層を０．
５〜５００μｍ厚さに形成せしめた場合に耐食性を向上
する効果をもたらすが、０．１％未満では効果が十分で
はなく、３％を超えて添加してもその効果が飽和するも
のであるから、Ａｌの含有量は０．１％以上３．０％以
下に限定する。また、前述の通りＡｌの含有量が０．３
％未満では、基材単体での孔食の発生を抑制する効果が
充分ではなく、一方、３．０％を超えて添加すると、そ
の効果は飽和するのに対して加工性を低下させるもので
あるから、Ａｌの含有量は０．３％以上３．０％以下と
することがより好ましい。Al: Al is the most important element for securing corrosion resistance in the present invention.
By adding the steel Al contained above, a metal layer whose electric potential in an aqueous solution environment is lower than that of the base material is added to the base material surface.
When formed to a thickness of 5 to 500 μm, the effect of improving the corrosion resistance is brought about. However, if it is less than 0.1%, the effect is not sufficient, and even if it exceeds 3%, the effect is saturated. , Al content is limited to 0.1% or more and 3.0% or less. Further, as described above, the content of Al is 0.3
%, The effect of suppressing the occurrence of pitting corrosion in the base material alone is not sufficient. On the other hand, if added over 3.0%, the effect is saturated, but the workability is reduced. Therefore, it is more preferable that the content of Al be 0.3% or more and 3.0% or less.

【００２６】Ｃ，Ｎ： ＣおよびＮは、鋼板の加工性を
低下させる上に、ＣはＣｒと炭化物を生成して耐食性を
低下させるので、またＮは靱性を低下させるので、Ｃお
よびＮ量は少ない方が望ましく、上限含有量はいずれも
０．０２％とし、いずれも少ないほど好ましい。更に、
優れた加工性を確保するためには、Ｃ＋Ｎの合計量を低
減する必要があり、本発明の望ましい態様による鋼とし
ては、Ｃ＋Ｎを０．０３％以下とする。C, N: C and N reduce the workability of the steel sheet, and also, C forms carbides with Cr to lower the corrosion resistance, and N lowers the toughness. The smaller the content, the better. The upper limit of the content is set to 0.02%, and the smaller the content, the better. Furthermore,
In order to ensure excellent workability, it is necessary to reduce the total amount of C + N. In a steel according to a preferred embodiment of the present invention, C + N is set to 0.03% or less.

【００２７】Ｐ： Ｐは、多量に存在すると靱性を低下
させるので少ない方が望ましく、上限含有量は０．０３
％とする。 Ｓ： Ｓも、多量に存在すると耐孔食性を低下させるの
で少ない方が望ましく、上限含有量は０．０１％とす
る。以上が本発明が対象とする耐食性に優れた鋼の基材
の基本的成分であるが、本発明においては、必要に応じ
て更に以下の元素を添加して耐食性を一段と向上させる
ことができる。P: Since a large amount of P lowers the toughness if it is present in a large amount, it is desirable that P is small, and the upper limit content is 0.03.
%. S: Since the presence of a large amount of S lowers the pitting corrosion resistance, the smaller the amount, the better. The upper limit content is 0.01%. The above are the basic components of the steel substrate excellent in corrosion resistance targeted by the present invention. In the present invention, the following elements can be further added as needed to further improve the corrosion resistance.

【００２８】Ｃｕ： Ｃｕは、Ａｌを０．１％以上含有
しＣｒを１０％以上含有する鋼に０．０１％以上添加す
ると、基材単体での全面腐食に対する抵抗を向上させる
効果があり、５．０％を超えて添加するとその効果は飽
和する。さらに基材表面に水溶液環境における電位が基
材よりも卑なる金属の層を０．５〜５００μｍ厚さに形
成せしめた場合に耐食性を向上する効果をもたらすが、
０．０５％未満では効果が認められず、一方約２．５％
を超えて添加してもその効果が飽和する。従って、０．
０５％以上２．５％以下の範囲で添加することがより望
ましい。Cu: Cu, when added to steel containing 0.1% or more of Al and 10% or more of Cr, in an amount of 0.01% or more, has an effect of improving resistance to general corrosion of the substrate alone. If the addition exceeds 5.0%, the effect saturates. Further, when the potential of the metal in the aqueous solution environment on the base material surface is made to be 0.5 to 500 μm thick with a metal layer which is more base than the base material, the effect of improving the corrosion resistance is brought about.
No effect is observed at less than 0.05%, while about 2.5%
The effect is saturated even if it is added in excess of. Therefore, 0.
It is more desirable to add it in the range of 05% or more and 2.5% or less.

【００２９】Ｍｏ： ＭｏはＡｌを０．１５％以上含有
しＣｒを１０％以上含有する鋼に添加することで、基材
表面に水溶液環境における電位が基材よりも卑なる金属
の層を０．５〜５００μｍ厚さに形成せしめた場合に耐
食性を向上する効果をもたらすが、０．０５％未満では
効果が認められず、一方１０％を超えて添加してもその
効果が飽和するので上限を１０％とする。さらにＭｏ
は、Ｃｒを１０％以上含有しＡｌを０．１％以上含有す
る鋼に０．１％以上添加すると、基材単体での孔食の発
生と成長を抑制する効果があるが、３．０％を超えて添
加してもその効果は飽和するばかりか加工性を低下させ
るので、上限含有量は３．０％とする。従って、０．１
％以上３％以下の範囲で添加することがより望ましい。Mo: Mo is added to a steel containing 0.15% or more of Al and 10% or more of Cr, so that a metal layer having a potential lower than that of the base material in an aqueous solution environment is formed on the surface of the base material. When formed to a thickness of 0.5 to 500 μm, the effect of improving the corrosion resistance is brought about, but if it is less than 0.05%, the effect is not recognized. To 10%. More Mo
Is effective in suppressing the occurrence and growth of pitting corrosion in the base material alone when 0.1% or more is added to steel containing 10% or more of Cr and 0.1% or more of Al. %, The effect is not only saturated, but also reduces the workability. Therefore, the upper limit content is set to 3.0%. Therefore, 0.1
More preferably, it is added in the range of not less than 3% and not more than 3%.

【００３０】Ｓｂ： Ｓｂは、Ａｌを０．１％以上含有
しＣｒを１０％以上含有する鋼に０．０１％以上添加す
ると、基材単体での孔食および全面腐食に対する抵抗を
向上させる効果があるが、０．５％を超えて添加すると
熱間加工性を低下させるので、上限含有量は０．５％と
する。さらにＳｂを添加することで、基材表面に水溶液
環境における電位が基材よりも卑なる金属の層を０．５
〜５００μｍ厚さに形成せしめた場合に耐食性を向上す
る効果をもたらすが、０．０１５％未満では効果が認め
られず、一方０．３％を超えて添加してもその効果が飽
和する。従って、０．０１５％以上０．３％以下の範囲
で添加することがより望ましい。Sb: Sb has an effect of improving resistance to pitting corrosion and general corrosion of a single base material when added to steel containing 0.1% or more of Al and 10% or more of Cr. However, if added in excess of 0.5%, the hot workability is reduced, so the upper limit content is set to 0.5%. Further, by adding Sb, the potential of the metal in the aqueous solution environment on the surface of the substrate becomes lower than that of the substrate by 0.5%.
When formed to a thickness of about 500 μm, the effect of improving the corrosion resistance is obtained. However, if the content is less than 0.015%, the effect is not recognized. On the other hand, the addition of more than 0.3% saturates the effect. Therefore, it is more desirable to add in the range of 0.015% or more and 0.3% or less.

【００３１】Ｎｉ： Ｎｉは、Ａｌを０．１％以上含有
しＣｒを１０％以上含有する鋼に０．０１％以上添加す
ると、基材単体での孔食を抑制する効果があるが、１０
％を超えて添加しても効果が飽和するばかりか熱間加工
性を低下させるので、上限含有量は１０％とする。さら
にＮｉを添加することで、基材表面に水溶液環境におけ
る電位が基材よりも卑なる金属の層を０．５〜５００μ
ｍ厚さに形成せしめた場合に耐食性を向上する効果をも
たらすが、０．１％未満では効果が認められず、一方６
％を超えて添加してもその効果が飽和する。従って、
０．１％以上６％以下の範囲で添加することがより望ま
しい。Ni: Ni has an effect of suppressing pitting corrosion of a single base material when added to steel containing 0.1% or more of Al and 10% or more of Cr by 0.01% or more.
%, The effect is not only saturated, but also reduces the hot workability. Therefore, the upper limit content is set to 10%. Further, by adding Ni, a metal layer whose electric potential in an aqueous solution environment is lower than that of the substrate on the surface of the substrate is 0.5 to 500 μm.
When formed to a thickness of m, the effect of improving the corrosion resistance is brought about.
%, The effect is saturated. Therefore,
It is more desirable to add in the range of 0.1% or more and 6% or less.

【００３２】Ｗ： Ｗは、Ａｌを０．１％以上含有しＣ
ｒを１０％以上含有する鋼に０．０５％以上添加する
と、基材単体での孔食の発生と成長を抑制する効果があ
るが、３．０％を超えて添加しても効果が飽和するばか
りか加工性を低下させるので、上限含有量は３．０％と
する。さらにＷを添加することで、基材表面に水溶液環
境における電位が基材よりも卑なる金属の層を０．５〜
５００μｍ厚さに形成せしめた場合に耐食性を向上する
効果をもたらすが、０．１％未満では効果が認められ
ず、一方２％を超えて添加してもその効果が飽和する。
従って、０．１％以上２％以下の範囲で添加することが
より望ましい。W: W contains 0.1% or more of Al and contains C
If 0.05% or more is added to steel containing 10% or more of r, there is an effect of suppressing the occurrence and growth of pitting corrosion in the base material alone, but the effect is saturated even if added over 3.0%. The upper limit of the content is set to 3.0%, because not only the workability but also the workability is reduced. By further adding W, the potential of the metal in the aqueous solution environment on the substrate surface becomes lower than that of the substrate by 0.5 to 0.5%.
When formed to a thickness of 500 μm, the effect of improving the corrosion resistance is brought about. However, if it is less than 0.1%, the effect is not recognized. On the other hand, if it exceeds 2%, the effect is saturated.
Therefore, it is more desirable to add in the range of 0.1% or more and 2% or less.

【００３３】希土類元素（ＲＥＭ）、Ｃａ： 希土類元
素（ＲＥＭ）およびＣａは熱間加工性の向上と基材単体
での耐孔食性の改善に効果のある元素であるが、添加量
がＲＥＭでは０．００１％未満、Ｃａでは０．０００１
％未満ではその効果が充分ではなく、ＲＥＭでは０．１
％を超えて、Ｃａでは０．０５％を超えて添加すると、
それぞれ粗大な非金属介在物を生成して逆に熱間加工性
や耐孔食性を劣化させるので、上限含有量は希土類元素
では０．１％、Ｃａでは０．０５％とした。更にＲＥＭ
やＣａはＡｌを０．１％以上含有しＣｒを１０％以上含
有する鋼に添加することで、基材表面に水溶液環境にお
ける電位が基材よりも卑なる金属の層を０．５〜５００
μｍ厚さに形成せしめた場合に耐食性を向上する効果を
もたらすが、Ｃａでは０．００５％未満では効果が認め
られず、ＲＥＭでは０．０１％未満では効果が認められ
ず、一方Ｃａでは０．０１％を、ＲＥＭでは０．０５％
を超えて添加してもその効果が飽和するばかりでなく、
熱間加工性や耐孔食性を劣化させる。従って、Ｃａは
０．００５％以上０．０１％以下の範囲で、ＲＥＭは
０．０１％以上０．０５％以下の範囲で添加することが
より望ましい。なお、本発明において希土類元素（ＲＥ
Ｍ）とは原子番号が５７〜７１番および８９〜１０３番
の元素およびＹを指す。Rare earth element (REM), Ca: Rare earth element (REM) and Ca are elements that are effective for improving hot workability and pitting corrosion resistance of the base material alone. Less than 0.001%, 0.0001 for Ca
%, The effect is not sufficient.
%, And for Ca over 0.05%,
Since the coarse nonmetallic inclusions are formed to deteriorate hot workability and pitting corrosion resistance, the upper limit content is set to 0.1% for rare earth elements and 0.05% for Ca. Further REM
And Ca are added to steel containing 0.1% or more of Al and 10% or more of Cr, so that a metal layer whose electric potential in an aqueous solution environment is lower than that of the base material is 0.5 to 500 on the base material surface.
When formed to a thickness of μm, the effect of improving the corrosion resistance is brought about. However, Ca has no effect at less than 0.005%, and REM has no effect at less than 0.01%, whereas Ca has no effect at less than 0.01%. 0.01% and 0.05% for REM
Not only does the effect saturate,
It degrades hot workability and pitting resistance. Therefore, it is more preferable that Ca is added in a range of 0.005% to 0.01%, and REM is added in a range of 0.01% to 0.05%. In the present invention, the rare earth element (RE
M) refers to elements having atomic numbers 57 to 71 and 89 to 103 and Y.

【００３４】本発明鋼は、以上説明した成分により優れ
た耐食性を付与すると共に、下記成分を更に添加するこ
とにより耐食性に加えて特に加工性を向上させることが
できる。Ｎｂ，Ｖ，Ｔｉ，Ｚｒ，Ｔａ，Ｈｆ： Ｎｂ，
Ｖ，Ｔｉ，Ｚｒ，Ｔａ，Ｈｆは含Ｃｒ鋼中のＣおよびＮ
を炭化物として固定することによって基材単体での耐食
性の向上や加工性の改善に顕著な効果があり、各元素単
独の添加あるいは２種以上の元素を複合して添加するこ
とができるが、単独での添加量が０．０１％未満では効
果がなく、１．０％を超えて添加するといたずらにコス
トを上昇させるとともに圧延疵等の原因ともなるので上
限含有量は１．０％とする。かつ、加工性を有効に改善
するためには、Ｎｂ，Ｖ，Ｔｉ，Ｚｒ，Ｔａ，Ｈｆの添
加量の合計が次式を満足することが必要である。The steel of the present invention imparts excellent corrosion resistance to the above-described components, and can further improve the workability, in addition to the corrosion resistance, by further adding the following components. Nb, V, Ti, Zr, Ta, Hf: Nb,
V, Ti, Zr, Ta and Hf represent C and N in Cr-containing steel.
Has a remarkable effect on the improvement of corrosion resistance and workability of the substrate alone by fixing as a carbide, and it is possible to add each element alone or to add two or more elements in combination. If the addition amount is less than 0.01%, there is no effect. If the addition amount exceeds 1.0%, the cost is increased unnecessarily and roll flaws are caused, so the upper limit content is set to 1.0%. Further, in order to effectively improve the workability, the total amount of Nb, V, Ti, Zr, Ta, and Hf needs to satisfy the following expression.

【００３５】Ｎｂ／９３＋Ｖ／５１＋Ｔｉ／４８＋Ｚｒ
／９１＋Ｔａ／１８１≧０．８×（Ｃ／１２＋Ｎ／１
４） さらにＴｉ，Ｚｒ，Ｔａ，ＨｆをＡｌを０．１５％以上
含有しＣｒを１０％以上含有する鋼に添加することで、
基材表面に水溶液環境における電位が基材よりも卑なる
金属の層を０．５〜５００μｍ厚さに形成せしめた場合
に耐食性を向上する効果をもたらすが、各元素共に約
０．０５％未満では効果が認められず、一方約０．８％
を超えて添加してもその効果が飽和する。従って、０．
０５％以上０．８％以下の範囲で添加することがより望
ましい。Nb / 93 + V / 51 + Ti / 48 + Zr
/91+Ta/181≧0.8×(C/12+N/1
4) Further, by adding Ti, Zr, Ta, and Hf to steel containing 0.15% or more of Al and 10% or more of Cr,
When a metal layer whose potential in an aqueous solution environment is lower than that of the substrate is formed to a thickness of 0.5 to 500 μm on the surface of the substrate, the effect of improving corrosion resistance is brought about, but each element is less than about 0.05%. Is not effective, while about 0.8%
The effect is saturated even if it is added in excess of. Therefore, 0.
More preferably, it is added in a range of from 0.05% to 0.8%.

【００３６】本発明においては、鋼基材表面、特に少な
くとも腐食環境に曝される面を、基材よりも電位が卑な
る金属で被覆する。基材よりも電位が卑なる金属で被覆
する厚さが０．５μｍ以下では、基材にＡｌを添加する
ことによる、基材表面が腐食環境に露出した後の残存す
る基材表面に被覆した、電位が基材よりも卑なる金属の
層の消失速度の低下と、基材表面の腐食環境に露出され
る面積の拡大速度の著しい低下、同時に、露出した基材
部分に対する基材表面に被覆した電位が基材よりも卑な
る金属の層の基材露出部分に対する保護作用が長期にわ
たって継続するという効果の発現が充分ではなく、５０
０μｍを超える厚さまで被覆しても、もはやその効果は
飽和しているのに対して、生産性を低下させて徒にコス
トを上昇させるだけであるから、被覆層の厚さは０．５
〜５００μｍとする。In the present invention, the surface of the steel substrate, particularly at least the surface exposed to the corrosive environment, is coated with a metal whose electric potential is lower than that of the substrate. At a thickness of 0.5 μm or less, which is coated with a metal whose potential is lower than that of the base material, by adding Al to the base material, the base material surface was coated on the remaining base material surface after being exposed to the corrosive environment. , The rate of disappearance of the metal layer whose potential is lower than that of the base material, and the rate of expansion of the area exposed to the corrosive environment on the base material surface are significantly reduced, and at the same time, the base material surface is coated on the exposed base part. The effect of protecting the exposed portion of the base material of the metal layer having a base potential lower than that of the base material over a long period of time is not sufficient.
Even if the coating is coated to a thickness exceeding 0 μm, the effect is no longer saturated, but only the productivity is reduced and the cost is simply increased.
５００500 μm.

【００３７】被覆層を形成する、水溶液環境における電
位が基材よりも卑なる金属としては、アルミニウム、亜
鉛、クロム、マンガン、およびこれらを主体とする合金
を使用することができる。また、被覆のプロセスは該金
属が基材に充分に固着されていればそのプロセスを限定
するものではない。用途やコスト等を考慮した上で選択
すれば良く、溶融メッキ、電着メッキ、溶融塩電解メッ
キ、真空蒸着、スパッタリング、イオンプレーティン
グ、溶射等を使用することができ、それらを併用するこ
とも可能である。また、被覆およびそのための処理の前
後に必要に応じていかなる処理を行なってもよい。Aluminum, zinc, chromium, manganese, and alloys mainly containing these can be used as the metal forming the coating layer and having a lower potential in an aqueous solution environment than the base material. The coating process is not limited as long as the metal is sufficiently fixed to the substrate. It should be selected in consideration of the application and cost, etc., and hot-dip plating, electrodeposition plating, molten salt electrolytic plating, vacuum evaporation, sputtering, ion plating, thermal spraying, etc. can be used, and they can be used together It is possible. In addition, any processing may be performed before and after the coating and the processing therefor as necessary.

【００３８】亜鉛を主体とする合金とは、合金成分のう
ち最大量を占める成分が亜鉛である合金すなわち亜鉛基
合金であり、一般に亜鉛基合金に含有されるアルミニウ
ム等の合金成分および不純物成分を含んでよい。アルミ
ニウムを主体とする合金とは、合金成分のうち最大量を
占める成分がアルミニウムである合金すなわちアルミニ
ウム基合金であり、一般にアルミニウム基合金に含有さ
れるシリコン、亜鉛等の合金成分および不純物成分を含
んでよい。The alloy mainly composed of zinc is an alloy in which the component occupying the largest amount among the alloy components is zinc, that is, a zinc-based alloy. Generally, an alloy component such as aluminum and an impurity component contained in the zinc-based alloy are removed. May include. An alloy mainly composed of aluminum is an alloy in which the component occupying the largest amount among the alloy components is aluminum, that is, an aluminum-based alloy, and generally includes an alloy component such as silicon and zinc and an impurity component contained in the aluminum-based alloy. Is fine.

【００３９】クロムを主体とする合金とは、合金成分の
うち最大量を占める成分がクロムである合金すなわちク
ロム基合金であり、一般にクロム基合金に含有されるシ
リコン等の合金成分および不純物成分を含んでよい。マ
ンガンを主体とする合金とは、合金成分のうち最大量を
占める成分がマンガンである合金すなわちマンガン基合
金であり、一般にマンガン基合金に含有されるアルミニ
ウム等の合金成分および不純物成分を含んでよい。The alloy mainly composed of chromium is an alloy in which the component occupying the largest amount among the alloy components is chromium, that is, a chromium-based alloy. Generally, an alloy component such as silicon and an impurity component contained in the chromium-based alloy are removed. May include. A manganese-based alloy is an alloy in which the component occupying the largest amount among the alloy components is manganese, that is, a manganese-based alloy, and may generally include an alloy component such as aluminum and an impurity component contained in the manganese-based alloy. .

【００４０】また、使用上の目的から、鋼管や板材等の
ように表裏面を有する材料の一方の面だけに被覆されて
いれば良い場合には、卑なる金属を被覆するプロセスか
ら片面のみが被覆される鋼を使用してもよい。このよう
な場合に片面だけの被覆を使用するか、あるいは両面に
被覆された鋼を使用するかは、コストや溶接性等の他の
要因を考慮して選択すれば良い。In addition, if only one surface of a material having front and back surfaces, such as a steel pipe or a plate material, needs to be coated for the purpose of use, only one surface is removed from the process of coating a base metal. Steel to be coated may be used. In such a case, whether to use coating on one side or steel coated on both sides may be selected in consideration of other factors such as cost and weldability.

【００４１】上記被覆を施す時期については、コイル、
板、棒、ケーブル、穿孔鋼管等の鋼材の一般的な形状と
した後に、本発明の被覆やそのための処理を行っても良
いし、被覆・処理後の本発明鋼をプレスやロール成形等
で所定の形状に成形し、更に加工・溶接して製品として
製造しても良いし、本発明の鋼を例えば電縫鋼管等とし
てまず鋼管の形状にした後に、２次加工および溶接等に
よって製品としても良く、更に、本発明の被覆・処理を
施す前に鋼材を上述したようなプロセスによって目的の
形状とした後に本発明の表面被覆処理を施すことも可能
であり、その他のプロセスも含めて本発明で限定する組
成および処理条件の組み合わせを有する鋼は、いずれも
本発明の対象とするところであって、コストや既存製造
設備の制約等によって最適な製品製造工程を選択するこ
とができ、どの製造工程を選択したとしてもそれをもっ
て本発明の範囲を逸脱するものではない。The timing for applying the coating is as follows.
After the steel, such as a plate, a rod, a cable, and a perforated steel pipe, is formed into a general shape, the coating of the present invention or a treatment therefor may be performed, or the coated and processed steel of the present invention may be pressed or roll-formed. It may be formed into a predetermined shape and further processed and welded to produce a product. It is also possible to apply the surface coating treatment of the present invention after forming the steel material into the target shape by the above-described process before performing the coating / treatment of the present invention. Any steel having a combination of composition and processing conditions limited by the present invention is a subject of the present invention, and an optimal product manufacturing process can be selected depending on costs, restrictions on existing manufacturing facilities, and the like. It would not be outside the scope of the present invention with a it even select process.

【００４２】以上の本発明において提案する鋼は、内燃
機関の排気系統をはじめとする高温湿潤腐食環境、結露
腐食環境はもとより、大気腐食環境、水道水腐食環境、
土壌腐食環境、コンクリート腐食環境、海水腐食環境、
飲料水腐食環境等の種々の腐食環境に適用することがで
きる。The steel proposed in the present invention described above can be used not only in an exhaust system of an internal combustion engine, but also in a high-temperature wet-corrosion environment, a condensation corrosion environment, an atmospheric corrosion environment, a tap water corrosion environment,
Soil corrosion environment, concrete corrosion environment, seawater corrosion environment,
The present invention can be applied to various corrosive environments such as a drinking water corrosive environment.

【００４３】[0043]

【実施例】以下に本発明の実施例について説明する。 〔耐食性の評価〕表１，２に成分を示す鋼を溶製し、熱
延、冷延等の通常の鋼板製造工程によって肉厚１mmの鋼
板とし、９００℃にて焼鈍を施した後、両面それぞれ
に、片面あたり１５±２μｍの条件で被覆を施した。表
１，２に示した被覆１はアルミニウム被覆、被覆２は亜
鉛被覆、被覆３はマンガン被覆、被覆４はクロム被覆を
それぞれ示す。Embodiments of the present invention will be described below. [Evaluation of Corrosion Resistance] Steel having the components shown in Tables 1 and 2 was melted, made into a steel plate having a thickness of 1 mm by a normal steel plate manufacturing process such as hot rolling or cold rolling, and then annealed at 900 ° C. Each was coated under the condition of 15 ± 2 μm per side. In Tables 1 and 2, coating 1 indicates aluminum coating, coating 2 indicates zinc coating, coating 3 indicates manganese coating, and coating 4 indicates chromium coating.

【００４４】次に、これらの鋼板から幅５０mm、長さ７
０mmの試験片を採取して、以下に述べる各種の腐食試験
に供した。高温湿潤腐食試験は、硫酸イオン１００ppm
、塩化物イオン３００ppm 、重炭酸イオン５００ppm
をアンモニウム塩の形で添加した水溶液５０cc中に試験
片を半分まで浸漬し、試験容器ごと１３０℃の雰囲気に
保持して試験溶液が完全に蒸発・揮散することを５０回
繰り返す試験とした。試験結果を表１，２に併せて示し
た。腐食試験結果の◎は最大腐食深さが０．１０mm未
満、○は０．２mm未満、△は０．３mm未満、×は０．３
mm以上であったことをそれぞれ示す。Next, from these steel plates, a width of 50 mm and a length of 7 mm were used.
A test piece of 0 mm was sampled and subjected to various corrosion tests described below. High-temperature wet corrosion test: 100 ppm of sulfate ion
, Chloride ion 300ppm, bicarbonate ion 500ppm
Was immersed in 50 cc of an aqueous solution in which was added in the form of an ammonium salt, and the test solution was repeated 50 times in which the test solution was completely evaporated and volatilized while keeping the test container in an atmosphere at 130 ° C. The test results are also shown in Tables 1 and 2. In the results of the corrosion test, ◎ indicates that the maximum corrosion depth is less than 0.10 mm, は indicates less than 0.2 mm, Δ indicates less than 0.3 mm, and × indicates 0.3.
mm or more.

【００４５】表１，２から明らかなように、本発明鋼
（番号１〜４０，５１〜９０）は塩化物を含む高温湿潤
という非常に厳しい腐食環境であっても良好な耐食性を
示しているのに対して、比較鋼（番号４１〜５０，１０
０〜１０９）は耐食性に劣ることがわかる。また、大気
環境や自動車排気系外面の塩害腐食を想定した試験とし
ては、５０℃−１時間の塩水噴霧後、６０℃で湿度９６
％の環境に５時間保持した後、更に１時間の冷凍保持を
行うことを３００回繰り返す塩害腐食試験とした。試験
後の試験片について最大孔食深さを測定し、試験結果と
した。最大孔食深さが０．２mm以下のものは◎、最大孔
食深さが０．２mmを超え０．４mm以下のものは○、最大
孔食深さが０．４mmを超え０．８mm以下のものは×、最
大孔食深さが０．８mmを超えるものは××で表示するこ
ととした。As is clear from Tables 1 and 2, the steels of the present invention (Nos. 1 to 40 and 51 to 90) show good corrosion resistance even in a very severe corrosive environment such as high-temperature wetting containing chloride. In contrast, comparative steels (numbers 41 to 50, 10
0-109) are inferior in corrosion resistance. In addition, as a test assuming salt damage caused by the atmospheric environment and the outer surface of an automobile exhaust system, after spraying salt water at 50 ° C. for one hour, a humidity of 96 ° C. and a humidity of 96 ° C.
% For 5 hours, followed by 1 hour of freezing and holding for 300 times. The maximum pit depth of the test specimen after the test was measured and used as the test result. If the maximum pit depth is 0.2mm or less, ◎, if the maximum pit depth is more than 0.2mm and 0.4mm or less, ○, the maximum pit depth is more than 0.4mm and 0.8mm or less , And those having a maximum pit depth exceeding 0.8 mm are indicated by XX.

【００４６】表１，２から明らかなように、本発明鋼
（番号１〜４０，５１〜９０）は塩害腐食という非常に
厳しい腐食環境であっても良好な耐食性を示しているの
に対して、比較鋼（番号４１〜５０，１００〜１０９）
は耐食性に劣ることがわかる。土壌腐食試験は、含水率
１５％、比抵抗４５０Ω・cmに塩化ナトリウム含有量で
調整した砂中に試験片を埋め込み、２５℃に保持して約
７００日放置する試験とした。試験結果を表１，２に併
せて示した。腐食試験結果の◎は最大腐食深さが０．０
５mm未満、○は０．１mm未満、△は０．５mm未満、×は
０．５mm以上であったことをそれぞれ示す。As is clear from Tables 1 and 2, the steels of the present invention (Nos. 1 to 40 and 51 to 90) exhibit good corrosion resistance even in a very severe corrosive environment such as salt damage corrosion. , Comparative steel (Nos. 41 to 50, 100 to 109)
Indicates that the corrosion resistance is inferior. The soil corrosion test was a test in which a test piece was embedded in sand adjusted to have a water content of 15% and a specific resistance of 450 Ω · cm with a sodium chloride content, and was left at 25 ° C. for about 700 days. The test results are also shown in Tables 1 and 2. ◎ in the corrosion test result indicates that the maximum corrosion depth is 0.0
Less than 5 mm, ○ indicates less than 0.1 mm, Δ indicates less than 0.5 mm, and X indicates 0.5 mm or more.

【００４７】表１，２から明らかなように、本発明鋼
（番号１〜４０，５１〜９０）は土壌腐食環境で良好な
耐食性を示しているのに対して、比較鋼（番号４１〜５
０，１００〜１０９）は耐食性に劣ることがわかる。コ
ンクリート中腐食試験は、塩化物を含む海砂を用いて混
練したポルトランドセメント中に試験片を埋め込みサン
プルとなし、凝固させた後、人工海水中にサンプルを半
分まで浸漬し、４５℃の環境に約７００日放置する試験
とした。試験結果を表１，２に併せて示した。腐食試験
結果の◎は腐食の発生が認められなかったもの、○は発
錆面積率が５％未満、△は発錆面積率が１０％未満、×
は１０％以上であったことをそれぞれ示す。As is clear from Tables 1 and 2, the steels of the present invention (Nos. 1 to 40 and 51 to 90) show good corrosion resistance in a soil corrosive environment, while the comparative steels (Nos.
0,100-109) are inferior in corrosion resistance. The corrosion test in concrete is performed by embedding a test piece in Portland cement kneaded with sea sand containing chloride, forming a sample, solidifying the sample, immersing the sample in artificial seawater by half, and placing it in a 45 ° C environment. It was a test that was left for about 700 days. The test results are also shown in Tables 1 and 2. In the results of the corrosion test, ◎ indicates that no corrosion was observed, は indicates that the rusting area ratio was less than 5%, Δ indicates that the rusting area rate was less than 10%, and ×.
Indicates that it was 10% or more.

【００４８】表１，２から明らかなように、本発明鋼
（番号１〜４０，５１〜９０）はコンクリート中腐食環
境で良好な耐食性を示しているのに対して、比較鋼（番
号４１〜５０，１００〜１０９）は耐食性に劣ることが
わかる。水道水環境腐食試験は、水道水中に試験片を浸
漬し、４５℃の雰囲気に１０ヶ月間保持する試験とし
た。試験結果を表１，２に併せて示した。腐食試験結果
の◎は腐食の発生が認められなかったもの、○は発錆面
積率が５％未満、△は発錆面積率が１０％未満、×は１
０％以上であったことをそれぞれ示す。As is clear from Tables 1 and 2, the steels of the present invention (Nos. 1 to 40 and 51 to 90) show good corrosion resistance in a corrosive environment in concrete, while the comparative steels (Nos. 50, 100 to 109) are inferior in corrosion resistance. The tap water environmental corrosion test was a test in which a test piece was immersed in tap water and kept in a 45 ° C. atmosphere for 10 months. The test results are also shown in Tables 1 and 2. In the results of the corrosion test, ◎ indicates that no corrosion was observed, は indicates that the rusting area ratio was less than 5%, △ indicates that the rusting area ratio was less than 10%, and × indicates that the rusting area ratio was less than 10%.
0% or more.

【００４９】表１，２から明らかなように、本発明鋼
（番号１〜４０，５１〜９０）は水道水腐食環境で良好
な耐食性を示しているのに対して、比較鋼（番号４１〜
５０，１００〜１０９）は耐食性に劣ることがわかる。
海水環境腐食試験は、海岸飛沫帯に試験片を１５ヶ月間
暴露する試験とした。試験結果を表１，２に併せて示し
た。腐食試験結果の◎は腐食深さ０．０５mm未満だった
もの、○は０．１mm未満、△は０．３mm未満、×は０．
３mm以上であったことをそれぞれ示す。As is clear from Tables 1 and 2, the steels of the present invention (Nos. 1 to 40 and 51 to 90) show good corrosion resistance in tap water corrosive environments, while the comparative steels (Nos.
50, 100 to 109) are inferior in corrosion resistance.
The seawater environment corrosion test was a test in which a test piece was exposed to a shore splash zone for 15 months. The test results are also shown in Tables 1 and 2. In the results of the corrosion test, ◎ indicates that the corrosion depth was less than 0.05 mm, O indicates less than 0.1 mm, Δ indicates less than 0.3 mm, and X indicates 0.
3 mm or more.

【００５０】表１，２から明らかなように、本発明鋼
（番号１〜４０，５１〜９０）は海水腐食環境で良好な
耐食性を示しているのに対して、比較鋼（番号４１〜５
０，１００〜１０９）は耐食性に劣ることがわかる。結
露腐食試験は、−２０℃の環境に２時間保持後湿度９８
％，３０℃の環境に４時間保持することを１３００回繰
り返す試験とした。試験結果を表１，２に併せて示し
た。腐食試験結果の◎は腐食の発生が認められなかった
もの、○は発錆面積率が５％未満、△は発錆面積率が１
０％未満、×は１０％以上であったことをそれぞれ示
す。表１，２から明らかなように、本発明鋼（番号１〜
４０，５１〜９０）は結露腐食環境で良好な耐食性を示
しているのに対して、比較鋼（番号４１〜５０，１００
〜１０９）は耐食性に劣ることがわかる。As is clear from Tables 1 and 2, the steels of the present invention (Nos. 1 to 40, 51 to 90) show good corrosion resistance in a seawater corrosive environment, while the comparative steels (Nos.
0,100-109) are inferior in corrosion resistance. The dew condensation corrosion test was conducted at a humidity of 98 after being kept in an environment of -20 ° C for 2 hours.
%, Which was maintained for 1 hour in an environment of 30 ° C. for 1300 times. The test results are also shown in Tables 1 and 2. In the results of the corrosion test, ◎ indicates that no corrosion was observed, は indicates that the rusting area ratio was less than 5%, and △ indicates that the rusting area ratio was 1
Less than 0%, and x indicates 10% or more, respectively. As is clear from Tables 1 and 2, the steels of the present invention (Nos.
40, 51 to 90) show good corrosion resistance in a dew-corrosion environment, while comparative steels (numbers 41 to 50, 100)
To 109) are inferior in corrosion resistance.

【００５１】大気腐食試験は、海岸から約４００ｍの位
置に試験片を約１０００日暴露する試験とした。試験結
果を表１，２に併せて示した。腐食試験結果の◎は腐食
が認められなかったもの、○は発錆面積率が３％未満、
△は発錆面積率が１０％未満、×は１０％以上であった
ことをそれぞれ示す。表１，２から明らかなように、本
発明鋼（番号１〜４０，５１〜９０）は大気腐食環境で
良好な耐食性を示しているのに対して、比較鋼（番号４
１〜５０，１００〜１０９）は耐食性に劣ることがわか
る。The atmospheric corrosion test was a test in which a test piece was exposed at a position of about 400 m from the coast for about 1,000 days. The test results are also shown in Tables 1 and 2. In the results of the corrosion test, ◎ indicates that no corrosion was observed, は indicates that the rusting area ratio was less than 3%,
Δ indicates that the rusting area ratio was less than 10%, and X indicates that it was 10% or more. As is clear from Tables 1 and 2, the steels of the present invention (Nos. 1 to 40 and 51 to 90) show good corrosion resistance in an atmospheric corrosion environment, while the comparative steels (No. 4)
1 to 50 and 100 to 109) are inferior in corrosion resistance.

【００５２】飲料水環境腐食試験は、水酸化ナトリウム
を用いてpHを２．３に調整し、高純度窒素ガスを通気し
て脱気し、２７℃に保持した、（ａ）０．５％リン酸溶
液、（ｂ）０．５％クエン酸溶液、（ｃ）０．５％クエ
ン酸−０．５％塩化ナトリウム溶液等の溶液８５０cc中
に試験片を３５日間浸漬し、溶液中に溶出した鉄イオン
量を分析する試験とした。なお本試験のみ、被覆１のア
ルミニウム被覆、被覆４のクロム被覆について試験を実
施した。試験結果を表１，２に併せて示した。腐食試験
結果の◎は溶液中への鉄イオンの溶出量が１ppm 以下、
○は３ppm 未満、△は５ppm 未満、×は５ppm 以上であ
ったことをそれぞれ示す。In the drinking water environmental corrosion test, the pH was adjusted to 2.3 using sodium hydroxide, degassed by passing high-purity nitrogen gas, and kept at 27 ° C. (a) 0.5% The test piece is immersed in a 850 cc solution of phosphoric acid solution, (b) 0.5% citric acid solution, (c) 0.5% citric acid-0.5% sodium chloride solution for 35 days, and eluted in the solution The test was conducted to analyze the amount of iron ions. In addition, only this test performed the test about the aluminum coating of the coating 1, and the chromium coating of the coating 4. The test results are also shown in Tables 1 and 2. In the results of the corrosion test, ◎ indicates that the elution amount of iron ions in the solution is 1 ppm or less,
は indicates less than 3 ppm, △ indicates less than 5 ppm, and X indicates 5 ppm or more.

【００５３】表１，２から明らかなように、本発明鋼
（番号１〜４０，５１〜９０）は飲料水腐食環境で良好
な耐食性を示しているのに対して、比較鋼（番号４１〜
５０，１００〜１０９）は耐食性に劣ることがわかる。
すなわち本発明鋼（番号１〜４０，５１〜９０）は高温
湿潤腐食環境、結露腐食環境、大気腐食環境、水道水腐
食環境、土壌腐食環境、コンクリート腐食環境、海水腐
食環境、飲料水腐食環境等の種々の腐食環境で良好な耐
食性を示しているのに対して、比較鋼（番号４１〜５
０，１００〜１０９）は耐食性に劣ることがわかる。 〔加工性の評価〕表２に成分を示す鋼を溶製し、熱延、
冷延など通常の鋼板製造工程によって、厚さ１．０mmの
鋼板とし、８５０℃にて焼鈍を施した。これらの鋼板か
ら幅１００mm長さ１００mmの試験片を採取し、絞り比
１．８の円筒絞り試験を行なって割れの有無で判定し
た。試験結果を表２に併せて示した。表２の加工性にお
いて○は円筒絞り試験結果が良好であったことを示し、
×は円筒絞り試験で割れを生じたことを示している。
尚、表２中のＸ値は、次式によって算出したものを記載
した。As is clear from Tables 1 and 2, the steels of the present invention (Nos. 1 to 40 and 51 to 90) show good corrosion resistance in a drinking water corrosive environment, while the comparative steels (Nos.
50, 100 to 109) are inferior in corrosion resistance.
That is, the steel of the present invention (Nos. 1 to 40, 51 to 90) is a high-temperature wet corrosion environment, dew condensation corrosion environment, atmospheric corrosion environment, tap water corrosion environment, soil corrosion environment, concrete corrosion environment, seawater corrosion environment, drinking water corrosion environment, and the like. Of the comparative steels (Nos. 41 to 5)
0,100-109) are inferior in corrosion resistance. [Evaluation of workability] Steel having the components shown in Table 2 was melted, hot rolled,
By a normal steel plate manufacturing process such as cold rolling, a steel plate having a thickness of 1.0 mm was annealed at 850 ° C. Test pieces having a width of 100 mm and a length of 100 mm were sampled from these steel sheets, and subjected to a cylindrical drawing test with a drawing ratio of 1.8 to determine whether or not cracks were present. The test results are also shown in Table 2. In the workability in Table 2, ○ indicates that the cylindrical drawing test result was good,
X indicates that a crack occurred in the cylindrical drawing test.
In addition, the X value in Table 2 described what was calculated by the following formula.

【００５４】Ｘ＝Ｎｂ／９３＋Ｖ／５１＋Ｔｉ／４８＋
Ｚｒ／９１＋Ｔａ／１８１＋Ｈｆ／１７９−０．８×
（Ｃ／１２＋Ｎ／１４） 表２から明らかなように、本発明鋼において特に加工性
を高めたもの（番号５１〜９０）は、良好な耐食性を示
し、かつ加工性も良好であった。すなわち、高温湿潤腐
食環境、結露腐食環境、大気腐食環境、水道水腐食環
境、土壌腐食環境、コンクリート腐食環境、海水腐食環
境、飲料水腐食環境等の種々の腐食環境で良好な耐食性
を示し、かつ加工性も優れている。これに対して、比較
鋼（番号１００〜１０９）は耐食性と加工性が同時に達
成できないことがわかる。X = Nb / 93 + V / 51 + Ti / 48 +
Zr / 91 + Ta / 181 + Hf / 179-0.8 ×
(C / 12 + N / 14) As is evident from Table 2, the steels of the present invention in which workability was particularly enhanced (Nos. 51 to 90) exhibited good corrosion resistance and good workability. That is, it shows good corrosion resistance in various corrosive environments such as high-temperature wet corrosive environment, dew condensation corrosive environment, atmospheric corrosive environment, tap water corrosive environment, soil corrosive environment, concrete corrosive environment, seawater corrosive environment, drinking water corrosive environment, and Excellent workability. On the other hand, it can be seen that the comparative steels (Nos. 100 to 109) cannot simultaneously achieve corrosion resistance and workability.

【００５５】[0055]

【表１】 [Table 1]

【００５６】[0056]

【表２】 [Table 2]

【００５７】[0057]

【表３】 [Table 3]

【００５８】[0058]

【表４】 [Table 4]

【００５９】[0059]

【表５】 [Table 5]

【００６０】[0060]

【表６】 [Table 6]

【００６１】[0061]

【表７】 [Table 7]

【００６２】[0062]

【表８】 [Table 8]

【００６３】[0063]

【発明の効果】以上述べたように、本発明によれば、例
えば自動車等の内燃機関の排気系統といった高温湿潤腐
食環境、結露腐食環境をはじめとして、更に大気腐食環
境、水道水腐食環境、土壌腐食環境、コンクリート腐食
環境、海水腐食環境、飲料水腐食環境等の種々の腐食環
境において耐食性に優れる耐食鋼が低コストで提供され
る。As described above, according to the present invention, in addition to a high-temperature wet corrosion environment such as an exhaust system of an internal combustion engine of an automobile or the like, a condensation corrosion environment, an atmospheric corrosion environment, a tap water corrosion environment, and a soil environment. Corrosion resistant steel having excellent corrosion resistance in various corrosive environments such as a corrosive environment, a concrete corrosive environment, a seawater corrosive environment, and a drinking water corrosive environment is provided at low cost.

Claims (8)

【特許請求の範囲】[Claims] 【請求項１】 重量％で、 Ｓｉ：０．０１〜３．０％、 Ｍｎ：０．０１〜３．０％、 Ｃｒ：１０〜３０％、 Ａｌ：０．１〜３％、残部Ｆｅおよび不可避的不純物か
らなり、該不可避的不純物のうちＣを０．０２％以下、
Ｐを０．０３％以下、Ｓを０．０１％以下、Ｎを０．０
２％以下に制限した鋼を基材とし、該基材の表面に、水
溶液環境における電位が該基材よりも卑なる金属の被覆
層を０．５〜５００μｍの厚さに形成したことを特徴と
する耐食鋼。1. wt%: Si: 0.01 to 3.0%, Mn: 0.01 to 3.0%, Cr: 10 to 30%, Al: 0.1 to 3%, balance Fe and Consisting of unavoidable impurities, of which C is 0.02% or less,
P is 0.03% or less, S is 0.01% or less, and N is 0.0% or less.
A steel substrate limited to 2% or less is used as a base material, and a metal coating layer having a potential lower than that of the base material in an aqueous solution environment is formed on the surface of the base material to a thickness of 0.5 to 500 μm. And corrosion resistant steel. 【請求項２】 前記基材の鋼が更に、重量％で、 Ｃｕ：０．０１〜５．０％、 Ｍｏ：０．０５〜１０％、 Ｓｂ：０．０１〜０．５％、 Ｎｉ：０．０１〜１０％、 Ｗ：０．０５〜３．０％、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に記載の耐食鋼。2. The steel of the base material further contains, by weight%, Cu: 0.01 to 5.0%, Mo: 0.05 to 10%, Sb: 0.01 to 0.5%, Ni: The corrosion-resistant steel according to claim 1, comprising one or more of 0.01 to 10%, and W: 0.05 to 3.0%. 【請求項３】 前記基材の鋼が更に、重量％で、 希土類元素：０．００１〜０．１％，Ｃａ：０．０００
１〜０．０５％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に記載の耐食鋼。3. The steel of the base material further contains, by weight%, a rare earth element: 0.001 to 0.1%, and Ca: 0.000.
The corrosion-resistant steel according to claim 1, wherein the steel contains 1 to 0.05% of one or more kinds. 【請求項４】 前記基材の鋼が更に、重量％で、Ｎｂ，
Ｖ，Ｔｉ，Ｚｒ，Ｔａ，Ｈｆの中から選ばれるいずれか
１種あるいは２種以上を単独含有量で０．０１〜１％含
有し、かつ次式を満足することを特徴とする請求項１，
２または３に記載の耐食鋼。 Ｎｂ／９３＋Ｖ／５１＋Ｔｉ／４８＋Ｚｒ／９１＋Ｔａ
／１８１≧０．８×（Ｃ／１２＋Ｎ／１４）4. The steel of the base material further comprises Nb,
2. The composition according to claim 1, wherein one or more selected from V, Ti, Zr, Ta, and Hf are contained in a single content of 0.01 to 1% and satisfy the following formula. ,
The corrosion-resistant steel according to 2 or 3. Nb / 93 + V / 51 + Ti / 48 + Zr / 91 + Ta
/181≧0.8×(C/12+N/14) 【請求項５】 前記被覆層の金属が、アルミニウムある
いはアルミニウムを主体とする合金のいずれかであるこ
とを特徴とする請求項１，２，３または４に記載の耐食
鋼。5. The corrosion-resistant steel according to claim 1, wherein the metal of the coating layer is one of aluminum and an alloy mainly containing aluminum. 【請求項６】 前記被覆層の金属が、亜鉛あるいは亜鉛
を主体とする合金のいずれかであることを特徴とする請
求項１，２，３または４に記載の耐食鋼。6. The corrosion-resistant steel according to claim 1, wherein the metal of the coating layer is one of zinc and an alloy mainly containing zinc. 【請求項７】 前記被覆層の金属が、クロムあるいはク
ロムを主体とする合金のいずれかであることを特徴とす
る請求項１，２，３または４に記載の耐食鋼。7. The corrosion-resistant steel according to claim 1, wherein the metal of the coating layer is one of chromium and an alloy mainly composed of chromium. 【請求項８】 前記被覆層の金属が、マンガンあるいは
マンガンを主体とする合金のいずれかであることを特徴
とする請求項１，２，３または４に記載の耐食鋼。8. The corrosion-resistant steel according to claim 1, wherein the metal of the coating layer is one of manganese and an alloy mainly containing manganese.