JP2006169626A5 - - Google Patents
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- JP2006169626A5 JP2006169626A5 JP2005331956A JP2005331956A JP2006169626A5 JP 2006169626 A5 JP2006169626 A5 JP 2006169626A5 JP 2005331956 A JP2005331956 A JP 2005331956A JP 2005331956 A JP2005331956 A JP 2005331956A JP 2006169626 A5 JP2006169626 A5 JP 2006169626A5
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- 229910000831 Steel Inorganic materials 0.000 claims description 145
- 239000010959 steel Substances 0.000 claims description 145
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- 229910001220 stainless steel Inorganic materials 0.000 description 2
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- HCHKCACWOHOZIP-UHFFFAOYSA-N zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N AI2O3 Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 229920000180 Alkyd Polymers 0.000 description 1
- IISBACLAFKSPIT-UHFFFAOYSA-N Bisphenol A Chemical compound C=1C=C(O)C=CC=1C(C)(C)C1=CC=C(O)C=C1 IISBACLAFKSPIT-UHFFFAOYSA-N 0.000 description 1
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- YCKRFDGAMUMZLT-UHFFFAOYSA-N fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 229910052735 hafnium Inorganic materials 0.000 description 1
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- 229910001562 pearlite Inorganic materials 0.000 description 1
- 239000005011 phenolic resin Substances 0.000 description 1
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- QAOWNCQODCNURD-UHFFFAOYSA-L sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
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Description
本発明は、高耐食性鋼材に関する技術分野に属するものであり、特には、橋梁、船舶、海洋構造物、他鋼構造物、建材、家電、自動車等に用いて好適な高耐食性鋼材に関する技術分野に属するものである。 The present invention belongs to a technical field related to high corrosion resistance steel materials, and in particular, to a technical field related to high corrosion resistance steel materials suitable for use in bridges, ships, marine structures, other steel structures, building materials, home appliances, automobiles, and the like. It belongs to.
腐食環境で使用される鋼は、めっき、塗装、溶射、電気防食などの対策のいずれかがなされることが一般的である。しかしながら、めっき、塗装、溶射などの表面皮膜には必ず何らかの微細欠陥があり、その部分の腐食が進行すると局部的に反応が大きく進行し、信頼性の面で必ずしも安全でない場合も多い。また、電気防食などは経済性の問題はいうに及ばず、装置の信頼性や設定条件を誤るとかえって腐食を進行させることもあり、完全なものではない。 In general, steel used in a corrosive environment is subjected to any of measures such as plating, painting, thermal spraying, and anticorrosion. However, surface coatings such as plating, painting, and thermal spraying always have some fine defects, and when the corrosion of the part progresses, the reaction proceeds locally and is not always safe in terms of reliability. In addition, the anticorrosion is not a complete problem because it goes without saying that the problem is economical, and if the reliability and setting conditions of the apparatus are wrong, corrosion may be caused.
近年、信頼性の向上や、製造・施工工程の簡素化、メンテナンスフリー化、経済的な要請、省資源等の観点から、鋼素地の耐食性向上を目的としたＣｒ含有鋼やステンレス鋼の使用が増大している。しかしながら、素材コストの上昇や溶接性、機械的特性、経済性等を考慮した場合に耐食性を満足する素材が使用できず、これらは抜本的な対策とならない場合が多い。 In recent years, the use of Cr-containing steels and stainless steels for the purpose of improving the corrosion resistance of steel bodies from the viewpoint of improving reliability, simplifying manufacturing and construction processes, making maintenance-free, economically demanding, saving resources, etc. It is increasing. However, in consideration of an increase in material cost, weldability, mechanical properties, economy, etc., materials that satisfy corrosion resistance cannot be used, and these are often not a drastic measure.
鋼素地の耐食性向上を目的とした鋼材として鋼にＣｒ，Ｃｕ，Ｎｉ，Ｐ等の化学成分を適量添加した耐候性鋼材があり、この耐候性鋼材としてＪＩＳに溶接構造用耐候性熱間圧延鋼材（ＳＭＡ：JIS G 3114）と高耐候性圧延鋼材（ＳＰＡ：JIS G 3125）の二種が規定されている。耐候性鋼は、鋼材表面に生成した緻密な安定錆層により永続的な腐食の進行を遮るといった鋼であり、内陸地方などマイルドな腐食環境等では使用実績がある。 As a steel material for the purpose of improving the corrosion resistance of the steel substrate, there is a weathering steel material in which an appropriate amount of chemical components such as Cr, Cu, Ni, P is added to the steel. As this weathering steel material, JIS has weather-resistant hot rolled steel material for welded structures. Two types are specified: (SMA: JIS G 3114) and high weatherability rolled steel (SPA: JIS G 3125). Weatherproof steel is steel that blocks the progress of permanent corrosion by a dense stable rust layer formed on the surface of the steel material, and has been used in mild corrosive environments such as inland areas.
従来の耐食性向上手段の中、表面処理については局部的腐食進行による信頼性の面で問題があり、電気防食などは装置や条件の問題、経済性の問題があり、Ｃｒ含有鋼やステンレス鋼は溶接性、機械的特性や素材コストの上昇や経済性を考慮した場合に耐食性を満足する素材が使用できず、抜本的な対策とならない場合が多い。 Among conventional means for improving corrosion resistance, surface treatment has problems in terms of reliability due to the progress of local corrosion, and electrocorrosion has problems with equipment and conditions, and there are economic problems. Cr-containing steel and stainless steel are In consideration of weldability, mechanical properties, material cost increase, and economic efficiency, it is often impossible to use a material that satisfies corrosion resistance, which is not a drastic measure.
耐候性鋼においては、安定な錆層を生成するまでには約１０年以上もの長期間を要し、実用上は初期の腐食及びそれに伴う赤錆の流出などが問題になっている。高温多湿な気候である日本では特にその傾向が強い。耐候性鋼を裸使用する際の錆安定化までの錆汁による周囲構造物の汚染などを防止する目的で、錆安定化処理が一般的に行われている。ただし、この方法も錆汁を防ぐのみで裸使用と同様、塩分が多く飛来する環境では緻密な錆層の生成が阻害され、期待した効果が得られないといった問題がある。 In weathering steel, a long period of about 10 years or more is required until a stable rust layer is formed, and in practical use, initial corrosion and accompanying outflow of red rust are problematic. This tendency is particularly strong in Japan, which has a hot and humid climate. Rust stabilization treatment is generally performed for the purpose of preventing contamination of surrounding structures by rust juice until rust stabilization when using weatherproof steel bare. However, this method also has a problem that the formation of a dense rust layer is inhibited and the expected effect cannot be obtained in an environment where a lot of salt comes in just like preventing bare rust soup.
このような問題点を解決する手段も従来から提案されている。例えば、特公昭53-22530号公報、特公昭56-33991号公報、特公昭58-39915号公報、特公昭58-17833号公報、特開平02-133480 号公報、特公平06-21273号公報等では、耐候性鋼の表面に樹脂を塗装することにより、外部環境からの飛来塩分の侵入を防ぎ、安定錆の生成を促進する方法が提案されている。上記特開平02-133480 号公報には、鱗片状結晶構造のFe3O4 、燐酸、ブチラール樹脂及び残部が溶剤である安定錆の生成を促進する表面処理液が開示されている。上記特公平06-21273号には、Ｐ，Ｃｕ，Ｃｒ，Ｎｉ，Ｓｉ及びＭｏの化合物の１種以上、Fe2O3 、Fe3O4 、燐酸、ビスフェノール系エポキシ樹脂及び残部が溶剤と塗料補助剤である塗装液を塗布する錆安定化表面処理方法が開示してある。 Means for solving such problems have been proposed. For example, JP-B 53-22530, JP-B 56-33991, JP-B 58-39915, JP-B 58-17833, JP-A 02-133480, JP-B 06-21273, etc. Then, a method has been proposed in which resin is applied to the surface of the weathering steel to prevent the entry of incoming salt from the external environment and promote the generation of stable rust. JP-A No. 02-133480 discloses a surface treatment solution that promotes the formation of stable rust having a scaly crystal structure of Fe 3 O 4 , phosphoric acid, butyral resin, and the balance being a solvent. In the above Japanese Patent Publication No. 06-21273, one or more compounds of P, Cu, Cr, Ni, Si and Mo, Fe 2 O 3 , Fe 3 O 4 , phosphoric acid, bisphenol-based epoxy resin and the balance are solvent and paint. A rust-stabilized surface treatment method for applying a coating liquid as an auxiliary agent is disclosed.
しかし、これらの方法はいずれも鋼材そのものを改善したものではなく、良い錆の生成を促進するには問題がある。即ち、樹脂塗装は、通常、微小な欠陥を有しており、その欠陥箇所においては塗膜の効果を期待できない。更には、塗膜欠陥部での腐食の進行は塗膜−素地界面での隙間腐食を引き起こすこととなり、安定錆層が生成する以前に塗膜自体の剥離、脱落を招くこともある。従って、塩分の飛来がさけられないような厳しい環境においての耐候性鋼の使用は制限を受けることとなり、大きな問題となっている。 However, none of these methods improve the steel material itself, and there is a problem in promoting the formation of good rust. That is, the resin coating usually has a minute defect, and the effect of the coating film cannot be expected at the defective portion. Furthermore, the progress of the corrosion at the coating film defect part causes crevice corrosion at the coating film-substrate interface, and the coating film itself may be peeled off or dropped before the stable rust layer is formed. Therefore, the use of weather-resistant steel in severe environments where salt content cannot be avoided is limited, which is a major problem.
鋼材そのものを改善したものとして、特開平１０−３３０８８１号公報（特許文献１）や特開平１１−７１６３２号公報（特許文献２）に記載のものがある。前者の特開平１０−３３０８８１号公報に記載のものは、Crフリー、Cu，Ni，Ti等の添加により、優れた耐候性が得られるというものである。しかし、機械的特性・溶接性・コストを勘案して合金添加量が制限され、それにより耐候性の向上が制限され、厳しい環境では耐候性が充分でないという問題点がある。後者の特開平１１−７１６３２号公報に記載のものは、Crフリー、Cu，Ni，Ti等の添加、さらに炭素当量特定により、耐候性を得つつ溶接性を確保する範囲を規定している。しかし、機械的特性・溶接性・コストを勘案して合金添加量を制限した結果、十分な耐食性が得られない。
鉄の耐食性向上のため、Cr，Cu，Niなどの耐食性向上元素の添加が常用されている。これらの元素は、一般的に、添加量が多いほど高い耐食性が得られるが、添加量が多くなるにつれて、機械的特性、溶接性の低下をきたすことが多く、更に、素材コストも高くなるため、元素添加量をなるべく低く抑えることが望ましい。 In order to improve the corrosion resistance of iron, the addition of elements that improve corrosion resistance such as Cr, Cu, and Ni is commonly used. In general, the higher the added amount, the higher the corrosion resistance of these elements. However, as the added amount increases, mechanical properties and weldability often decrease, and the material cost also increases. It is desirable to keep the element addition amount as low as possible.
このように、耐食性の向上と鋼材特性やコストパフォーマンスの向上とは二律背反であり、両者を十分に満足するべく多くの検討が実施されているが、どこかのバランス点で妥協せざえるをえない。 In this way, improving corrosion resistance and improving steel properties and cost performance are trade-offs, and many studies have been conducted to fully satisfy the two, but there is a compromise between some balance points. Absent.
本発明はこのような事情に着目してなされたものであって、その目的は、耐食性向上元素の過剰な添加による機械的特性および溶接性の低下をきたすことなく、優れた耐食性を有することができる高耐食性鋼材を提供しようとするものである。 The present invention has been made paying attention to such circumstances, and its purpose is to have excellent corrosion resistance without causing deterioration of mechanical properties and weldability due to excessive addition of an element for improving corrosion resistance. It is intended to provide a highly corrosion-resistant steel material that can be used.
本発明者らは、上記目的を達成するため、鋭意研究を行なった結果、本発明を完成するに至った。本発明によれば上記目的を達成することができる。 In order to achieve the above object, the present inventors have intensively studied, and as a result, completed the present invention. According to the present invention, the above object can be achieved.
このようにして完成され上記目的を達成することができた本発明は、高耐食性鋼材に係わり、特許請求の範囲の請求項１〜４記載の高耐食性鋼材（第１〜４発明に係る高耐食性鋼材）であり、それは次のような構成としたものである。 The present invention thus completed and capable of achieving the above object relates to a high corrosion resistance steel material, and the high corrosion resistance steel material according to claims 1 to 4 (high corrosion resistance according to the first to fourth inventions). Steel), which has the following configuration.
即ち、請求項１記載の高耐食性鋼材は、Ｃ：０．０２〜０．２０質量％、Ｍｎ：０．１〜２．５質量％、Ｓｉ：０．０３〜１．０質量％、Ａｌ：０．０３〜０．５質量％、Ｔｉ：０．０１〜０．１質量％、Ｐ：０．１質量％以下、Ｓ：０．００５質量％以下、Ｃｒ：０．５質量％以下、Ｚｎ：０．０１〜３．０質量％、Ｃｕ：０．０５〜３．０質量％、Ｎｉ：０．０５〜６．０質量％を含有し、更に、Ｃａ：０．０００５〜０．００５０質量％、Ｍｇ：０．０００５〜０．０１０質量％、ＲＥＭ：０．０００５〜０．０１０質量％のいずれか１種または２種以上を含有し、残部Ｆｅおよび不可避的不純物からなることを特徴とする高耐食性鋼材である〔第１発明〕。 That is, the high corrosion resistance steel material according to claim 1 is : C: 0.02 to 0.20 mass%, Mn: 0.1 to 2.5 mass%, Si: 0.03 to 1.0 mass%, Al: 0.03-0.5 mass%, Ti: 0.01-0.1 mass%, P: 0.1 mass% or less, S: 0.005 mass% or less, Cr: 0.5 mass% or less, Zn : 0.01 to 3.0 mass%, Cu: 0.05 to 3.0 mass%, Ni: 0.05 to 6.0 mass%, and Ca: 0.0005 to 0.0050 mass %, Mg: 0.0005 to 0.010 mass%, REM: 0.0005 to 0.010 mass%, containing one or more of the remaining Fe and unavoidable impurities It is a highly corrosion-resistant steel material [first invention].
請求項２記載の高耐食性鋼材は、更にＮｂ：０．００５〜０．１０質量％、Ｖ：０．０１〜０．２０質量％、Ｚｒ：０．００５〜０．１０質量％、Ｍｏ：０．１〜１．０質量％、Ｂ：０．０００３〜０．００３０質量％のいずれか１種または２種以上を含有する請求項１記載の高耐食性鋼材である〔第２発明〕。 The high corrosion resistance steel material according to claim 2 further includes Nb: 0.005 to 0.10 mass%, V: 0.01 to 0.20 mass%, Zr: 0.005 to 0.10 mass%, Mo: 0. .1～1.0 mass%, B: from 0.0003 to .0030 a highly corrosion-resistant steel according to claim 1, further comprising either one or more mass% second invention].
請求項３記載の高耐食性鋼材は、鋼材最表面から深さ５００μｍまでの領域に、Ｃｕ量＋Ｎｉ量が鋼材のＣｕ量＋Ｎｉ量の１．２倍以上であり、且つ、１．０質量％以上であるＣｕ＋Ｎｉ濃化層を有し、その濃化層の厚さが１μｍ以上である請求項１または２記載の高耐食性鋼材である〔第３発明〕。 The highly corrosion-resistant steel material according to claim 3 has a Cu amount + Ni amount that is 1.2 times or more of the Cu amount + Ni amount of the steel material and 1.0% by mass or more in the region from the outermost surface of the steel material to a depth of 500 μm. has a Cu + Ni-enriched layer, the thickness of the concentrated layer is highly corrosion-resistant steel according to claim 1 or 2, wherein at 1μm or more third invention] is.
請求項４記載の高耐食性鋼材は、前記鋼材が鋼板であって、この鋼板の表裏面のそれぞれの表面から板厚方向に板厚の１０％〜３０％の領域における平均フェライト粒径が５μｍ以下である請求項１〜３のいずれかに記載の高耐食性鋼材である〔第４発明〕。 The high corrosion resistance steel material according to claim 4 , wherein the steel material is a steel plate, and an average ferrite particle size in a region of 10% to 30% of the plate thickness in the plate thickness direction from the front and back surfaces of the steel plate is 5 μm or less. It is a high corrosion-resistant steel material in any one of Claims 1-3 [ 4th invention].
なお、上記のＲＥＭは希土類金属元素のことである。以降のＲＥＭも同様である（希土類金属元素のことである）。 The above REM is a rare earth metal element. The same applies to the subsequent REMs (rare earth metal elements).
本発明に係る高耐食性鋼材によれば、耐食性向上元素の過剰な添加による機械的特性および溶接性の低下をきたすことなく、優れた耐食性を有することができる。 The high corrosion resistance steel material according to the present invention can have excellent corrosion resistance without causing deterioration of mechanical properties and weldability due to excessive addition of an element for improving corrosion resistance.
本発明に係る高耐食性鋼材においては、Ｚｎ添加によりＦｅが溶解しやすくなり、鋼材の表層部にＣｕ、Ｎｉが濃化することにより、少ないＣｕ、Ｎｉ添加量であってＣｕ、Ｎｉ量の多いものに相当する耐食性が得られる。即ち、耐食性向上の効果があるＣｕ、Ｎｉを鋼材全体としては機械的特性や溶接性の低下をきたさないような少量の濃度に抑え、耐食性に寄与する表面にＣｕ、Ｎｉを濃化させて高濃度とすることにより、耐食性を向上させる。更に、Ｃａ、Ｍｇ、ＲＥＭ（希土類金属元素）の１種以上の添加により、腐食先端部のｐＨ低下を抑制する作用等によって耐食性を向上させる。 In the high corrosion resistance steel material according to the present invention, Fe is easily dissolved by addition of Zn, and Cu and Ni are concentrated in the surface layer portion of the steel material, so that the amount of Cu and Ni is small and the amount of Cu and Ni is large. Corrosion resistance equivalent to that is obtained. That is, Cu and Ni, which have an effect of improving corrosion resistance, are suppressed to a small amount so as not to cause deterioration of mechanical properties and weldability as a whole steel material, and Cu and Ni are concentrated on the surface contributing to corrosion resistance. By making the concentration, the corrosion resistance is improved. Furthermore, by adding one or more of Ca, Mg, and REM (rare earth metal elements), the corrosion resistance is improved by the action of suppressing the pH drop at the corrosion tip.
上記の鋼材表面でのＣｕ、Ｎｉの濃化は、ＺｎをＣｕ、Ｎｉと複合添加することにより達成できる。Ｚｎは電気化学的に卑で鉄（Ｆｅ）に広い組成範囲で固溶するので、腐食環境中へのＦｅの溶解を促進させる作用がある。これは一時的に鋼材の耐食性が低下することを意味するが、腐食初期にＺｎとＦｅが優先溶解することにより、鋼材表面にＣｕ、Ｎｉが取り残される形で濃化し、鋼材表面でのＣｕ、Ｎｉの濃度が高くなる。即ち、鋼材表面にＣｕ、Ｎｉが濃化した層（以下、Ｃｕ、Ｎｉ濃化層または濃化層という）が形成される。このとき、Ｚｎ量、Ｃｕ量、Ｎｉ量については、上記耐食性の点からＺｎ：０．０１質量％以上、Ｃｕ：０．０５質量％以上、Ｎｉ：０．０５質量％以上とすることが必要である。また、上記耐食性以外の特性等の点からＺｎ：３．０質量％以下、Ｃｕ：３．０質量％以下、Ｎｉ：６．０質量％以下とすることが必要である。 Concentration of Cu and Ni on the steel material surface can be achieved by composite addition of Zn and Cu and Ni. Zn is electrochemically base and dissolves in a wide composition range in iron (Fe), and therefore has an action of promoting dissolution of Fe in a corrosive environment. This means that the corrosion resistance of the steel material is temporarily reduced, but Zn and Fe are preferentially dissolved in the early stage of corrosion, so that Cu and Ni are left behind on the steel material surface, Cu on the steel material surface, The concentration of Ni increases. That is, a layer in which Cu and Ni are concentrated (hereinafter referred to as Cu, Ni concentrated layer or concentrated layer) is formed on the steel material surface. At this time, the Zn content, Cu content, and Ni content must be Zn: 0.01% by mass or more, Cu: 0.05% by mass or more, and Ni: 0.05% by mass or more in view of the above corrosion resistance. It is. Further, Zn from the viewpoint of the characteristics other than the corrosion resistance: 3.0 wt% or less, Cu: 3.0 wt% or less, Ni: it is necessary to 6.0 mass% or less.
更に、Ｃａ、Ｍｇ、ＲＥＭのいずれか１種以上を含有すると、耐食性向上効果が飛躍的に高まる。即ち、Ｚｎ、Ｃｕ、Ｎｉを添加すると共にＣａ、Ｍｇ、ＲＥＭのいずれか１種以上を添加することにより、耐食性が大幅に向上する。これは、Ｃａ、Ｍｇ、ＲＥＭは、腐食先端部のｐＨ低下を抑制する作用や、孔食の起点となり耐候性を低下させるＭｎＳの生成を抑制する働き、及び、腐食初期にＺｎとＦｅを安定的に腐食させる効果があるからである。このとき、Ｃａ量、Ｍｇ量、ＲＥＭ量については、上記耐食性効果の点からＣａ：０．０００５質量％以上、Ｍｇ：０．０００５質量％以上、ＲＥＭ：０．０００５質量％以上とすることが必要である。また、上記耐食性以外の特性等の点からＣａ：０．００５０質量％以下、Ｍｇ：０．０１０質量％以下、ＲＥＭ：０．０１０質量％以下とすることが必要である。 Furthermore, when any one or more of Ca, Mg, and REM are contained, the corrosion resistance improving effect is remarkably increased. That is, by adding Zn, Cu, Ni and at least one of Ca, Mg, and REM, the corrosion resistance is greatly improved. This is because Ca, Mg, and REM suppress the pH drop at the corrosion tip, suppress the generation of MnS that becomes the starting point of pitting corrosion and lower the weather resistance, and stabilize Zn and Fe in the early stage of corrosion. This is because it is effective to corrode. At this time, Ca amount, Mg amount, and REM amount are set to Ca: 0.0005 mass% or more, Mg: 0.0005 mass% or more, REM: 0.0005 mass% or more from the viewpoint of the corrosion resistance effect. is necessary. Further, Ca from the viewpoint of the characteristics other than the corrosion resistance: 0.0050 wt% or less, Mg: 0.010 wt% or less, REM: it is necessary to 0.010 mass% or less.
このように、本発明に係る高耐食性鋼材は、鋼材表面にＣｕ、Ｎｉが濃化し鋼材表面でのＣｕ、Ｎｉの濃度が高くなるので、これにより耐食性が向上し、更に、Ｃａ、Ｍｇ、ＲＥＭのいずれか１種以上の添加により耐食性が向上し、優れた耐食性を有することができる。また、Ｃｕ、Ｎｉの添加量は少なく、鋼材全体としては濃度が低く、この量は機械的特性および溶接性の低下をきたすような過剰な添加量ではない。更に、Ｃａ、Ｍｇ、ＲＥＭのいずれか１種以上の添加量も機械的特性および溶接性の低下をきたすような量ではない。 As described above, the high corrosion resistance steel material according to the present invention concentrates Cu and Ni on the surface of the steel material and increases the concentration of Cu and Ni on the surface of the steel material, thereby improving the corrosion resistance, and further, Ca, Mg, and REM. Addition of one or more of these can improve the corrosion resistance, and can have excellent corrosion resistance. Further, the addition amount of Cu and Ni is small, and the concentration of the steel material as a whole is low. This amount is not an excessive addition amount that causes deterioration of mechanical properties and weldability. Furthermore, the addition amount of at least one of Ca, Mg, and REM is not such an amount that the mechanical characteristics and weldability are deteriorated.
従って、本発明に係る高耐食性鋼材は、耐食性向上元素（Ｃｕ、Ｎｉ等）の過剰な添加による機械的特性および溶接性の低下をきたすことなく、優れた耐食性を有することができる〔第１発明〕。即ち、耐食性向上元素（Ｃｕ、Ｎｉ等）の添加量は機械的特性および溶接性の低下をきたさない程度の少量であるが、優れた耐食性を有することができる。 Therefore, the high corrosion resistance steel material according to the present invention can have excellent corrosion resistance without deteriorating mechanical properties and weldability due to excessive addition of elements for improving corrosion resistance (Cu, Ni, etc.) [First Invention ]. That is, the amount of the corrosion resistance improving element (Cu, Ni, etc.) added is a small amount that does not cause deterioration in mechanical properties and weldability, but can have excellent corrosion resistance.
本発明に係る高耐食性鋼材〔第１発明〕において、各成分の添加理由を説明する。
Ｃは鋼の強度に効く元素であり、３９０〜６３０Ｎ／ｍｍ 2 級乃至それ以上の強度の確保に際し有効な元素であるが、Ｃ：０．２質量％超の場合には鋼の溶接性や裸耐候性を劣化させ、Ｃ：０．０２質量％未満では上記強度確保が難しくなる。かかる点から、Ｃ：０．０２〜０．２０質量％とする。
In the high corrosion resistance steel material according to the present invention [first invention], the reason for adding each component will be described.
C is an element effective for the strength of steel, and is an element effective for securing a strength of 390 to 630 N / mm 2 grade or higher, but when C: more than 0.2% by mass, The bare weather resistance is deteriorated, and if the C content is less than 0.02% by mass, it is difficult to ensure the strength. From this point, C: 0.02 to 0.20 mass%.
Ｍｎは鋼の強度に効く元素であり、Ｃに替わり３９０〜６３０Ｎ／ｍｍMn is an element that works on the strength of steel, and instead of C, 390-630 N / mm 2 2 級乃至それ以上の強度の確保に有効な元素であるが、Ｍｎ：２．５質量％超の場合には、ＭｎＳが鋼中に多量に生成して、裸耐候性などの耐食性の劣化を招くおそれがある。Ｍｎ：０．１質量％未満では、上記強度確保が難しくなる。かかる点から、Ｍｎ：０．１〜２．５質量％とする。Although it is an element effective for securing a strength of grade or higher, if Mn: more than 2.5% by mass, a large amount of MnS is formed in the steel, resulting in deterioration of corrosion resistance such as bare weather resistance. There is a fear. If Mn is less than 0.1% by mass, it is difficult to ensure the strength. From this point, Mn: 0.1 to 2.5% by mass.
Ｓｉは溶鋼の脱酸や固溶強化のための元素であり、また、緻密な安定錆層の形成を促進し、裸耐候性などの耐食性を向上させる効果も有する。しかし、Ｓｉ：０．０３質量％未満では、これらの効果が不十分である。Ｓｉ：１．０質量％超の場合には、溶接性が低下する。このような点から、Ｓｉ：０．０３〜１．０質量％とする。Ｓｉの下限値は０．１質量％とすることが望ましい。即ち、Ｓｉ：０．１〜１．０質量％とすることが望ましい。Si is an element for deoxidation and solid solution strengthening of molten steel, and also has an effect of promoting the formation of a dense stable rust layer and improving corrosion resistance such as bare weather resistance. However, these effects are insufficient when Si is less than 0.03 mass%. In the case of Si: more than 1.0% by mass, the weldability is lowered. From such a point, Si: 0.03 to 1.0% by mass. The lower limit value of Si is preferably 0.1% by mass. That is, Si: 0.1 to 1.0% by mass is desirable.
ＡｌはＴｉと複合添加することにより安定錆層の形成を一層促進し、ひいては耐食性を更に向上させる効果を有する。また、Ａｌは溶接性の向上効果も有する。更に、Ａｌは、溶鋼の脱酸元素として、固溶酸素を捕捉するとともに、ブローホールの発生を防止して、鋼の靱性の向上のためにも有効な元素である。Ａｌ：０．０３質量％未満では、これらの効果が十分には得られず、一方、Ａｌ：０．５質量％超では、上記の安定錆層形成の促進による耐食性向上の効果は飽和し、逆に、溶接性を劣化させたり、アルミナ系介在物の増加により鋼の靱性を劣化させる。このような点から、Ａｌ：０．０３〜０．５質量％とする。Ａｌの下限値は０．１質量％とすることが望ましい。即ち、Ａｌ：０．１〜０．５質量％とすることが望ましい。When Al is added in combination with Ti, the formation of a stable rust layer is further promoted, and the corrosion resistance is further improved. Al also has an effect of improving weldability. Furthermore, Al is an element effective for improving the toughness of steel by capturing solid solution oxygen as a deoxidizing element of molten steel and preventing the occurrence of blowholes. When Al: less than 0.03% by mass, these effects cannot be sufficiently obtained. On the other hand, when Al: more than 0.5% by mass, the effect of improving the corrosion resistance by promoting the formation of the stable rust layer is saturated. On the other hand, the toughness of the steel is deteriorated by degrading the weldability or increasing the number of alumina inclusions. From such points, Al: 0.03 to 0.5 mass% is set. The lower limit value of Al is preferably 0.1% by mass. That is, it is desirable that Al: 0.1 to 0.5% by mass.
塩化物環境での耐候性や、耐局部腐食性、耐穴あき性の改善には、特にＴｉ添加が有効である。必要なＴｉ量は０．０１〜０．１質量％である。望ましいＴｉ量は０．０３５〜０．０５質量％である。Addition of Ti is particularly effective for improving weather resistance in a chloride environment, local corrosion resistance, and perforation resistance. The necessary amount of Ti is 0.01 to 0.1% by mass. A desirable amount of Ti is 0.035 to 0.05 mass%.
Ｃｒは大気中や海水中においては耐食性向上元素である。しかし、大気の塩化物環境では却って悪影響を及ぼす。このような環境ではＣｒ量を低減することにより、特に耐孔あき性が向上する。このような耐孔あき性や、耐局部腐食性の改善、塩分環境下における耐食性向上には、特にＣｒ低減が有効であり、Ｃｒ：０．５質量％以下にすることが必要である。Ｃｒ：０．２質量％以下にすることが望ましく、Ｃｒフリー化することは更に望ましい。Cr is an element that improves corrosion resistance in the air and seawater. However, it is adversely affected in the atmospheric chloride environment. In such an environment, the perforation resistance is particularly improved by reducing the Cr content. In order to improve such perforation resistance, local corrosion resistance, and corrosion resistance in a salt environment, Cr reduction is particularly effective, and Cr: 0.5 mass% or less is necessary. Cr: 0.2% by mass or less is desirable, and Cr-free is more desirable.
Ｚｎ、Ｃｕ、Ｎｉ、Ｃａ、Ｍｇ、ＲＥＭは特に重要な成分である。本発明に係る高耐食性鋼材〔第１発明〕において、Ｚｎは、鋼の耐食性を向上させるのに必須であり、ＺｎはＦｅ母材を溶解しやすくし、耐食性向上元素を濃化させる。また、Ｚｎは、生成錆を緻密化、微細化させ保護性さび形成に非常に優位に働く機能を有する。更に、亜鉛の腐食生成物が鋼材表面を覆い、環境遮断膜の役割を果たすという効果がある。Zn, Cu, Ni, Ca, Mg, and REM are particularly important components. In the high corrosion resistance steel material according to the present invention [first invention], Zn is essential for improving the corrosion resistance of the steel, and Zn easily dissolves the Fe base material and concentrates the corrosion resistance improving element. Moreover, Zn has a function that makes the generated rust dense and fine, and works very preferentially in forming protective rust. Further, the corrosion product of zinc covers the steel material surface and has an effect of acting as an environmental barrier film.
Ｚｎ：０．０１〜３．０質量％としているのは、Ｚｎ：０．０１質量％未満の場合、耐食性向上元素の濃化が不充分となり、ひいては耐食性向上が不充分となり、Ｚｎ：３．０質量％超の場合、鋼材溶解が進み耐食性が劣化するからである。このような耐食性の点から、望ましいＺｎ量は０．０２〜０．１質量％である。Zn: 0.01 to 3.0% by mass, when Zn: less than 0.01% by mass, the concentration of the corrosion resistance-improving element is insufficient, and consequently the corrosion resistance is insufficiently improved. This is because when the content exceeds 0% by mass, dissolution of the steel material proceeds and corrosion resistance deteriorates. In view of such corrosion resistance, the desirable Zn amount is 0.02 to 0.1% by mass.
Ｃｕは、耐食性向上効果や溶接性向上効果を有する元素である。Ｃｕは電気化学的に鉄より貴な元素であり、鋼表面に生成する錆を緻密化して、安定錆層の形成を促進し、耐候性などの耐食性を向上させる効果もある。また、溶接性の向上にも寄与する。Cu is an element having an effect of improving corrosion resistance and an effect of improving weldability. Cu is an element electrochemically more noble than iron, and has the effect of densifying the rust produced on the steel surface, promoting the formation of a stable rust layer, and improving the corrosion resistance such as weather resistance. It also contributes to improved weldability.
Ｃｕ：０．０５〜３．０質量％としているのは、Ｃｕ：０．０５質量％未満の場合には耐食性向上が不充分となり、Ｃｕ：３．０質量％超の場合には耐食性向上効果が飽和し、また、鋼材の製造のための熱間圧延等の加工の際に、素材の脆化（以下、熱間加工脆性ともいう）を引き起こす可能性があるからである。なお、上記熱間加工脆性の発生をより確実に抑制するためには、Ｃｕ含有量を０．５％以下とすることが好ましい。即ち、Ｃｕ：０．０５〜０．５％とすることが望ましい。Cu: 0.05 to 3.0% by mass is insufficient for improving corrosion resistance when Cu is less than 0.05% by mass, and for improving corrosion resistance when Cu is more than 3.0% by mass. This is because there is a possibility that the material becomes saturated and embrittlement of the material (hereinafter also referred to as hot work embrittlement) may occur during processing such as hot rolling for the production of steel. In order to more reliably suppress the occurrence of hot work brittleness, the Cu content is preferably 0.5% or less. That is, Cu: 0.05 to 0.5% is desirable.
Ｎｉは、耐食性向上効果や溶接性向上効果を有する元素である。ＮｉはＣｕの場合と同様に、鋼表面に生成する錆を緻密化して、安定錆層の形成を促進し、耐候性等の耐食性を向上させる効果を有する。また、溶接性の向上にも寄与する。更に、Ｎｉは、前記熱間加工脆性を抑制する効果もある。従って、ＮｉをＣｕと併せて含有させることにより、耐食性向上効果、熱間加工脆性の抑制効果の相乗効果が期待できる。Ni is an element having an effect of improving corrosion resistance and an effect of improving weldability. Ni, like Cu, has the effect of densifying the rust produced on the steel surface, promoting the formation of a stable rust layer, and improving the corrosion resistance such as weather resistance. It also contributes to improved weldability. Furthermore, Ni also has the effect of suppressing the hot work brittleness. Therefore, by containing Ni together with Cu, a synergistic effect of improving corrosion resistance and suppressing hot work brittleness can be expected.
Ｎｉ：０．０５〜６．０質量％としているのは、Ｎｉ：０．０５質量％未満の場合、耐食性の向上が不充分となり、一方、Ｎｉ：６．０質量％超の場合、完全オーステナイト組織における固液凝固温度範囲を広げて、低融点不純物元素のデンドライト粒界への偏析を助長するとともに、Ｓと反応して溶接金属の粒界に、低融点のＮｉＳ化合物を析出させ、凝固金属の粒界の延性を劣化させ、ひいては、耐溶接高温割れ性に悪影響を与えるからである。Ni: 0.05-6.0% by mass means that when Ni: less than 0.05% by mass, the corrosion resistance is insufficiently improved. On the other hand, when Ni: more than 6.0% by mass, complete austenite The solid-liquid solidification temperature range in the structure is expanded to promote the segregation of low melting point impurity elements to the dendrite grain boundaries and to react with S to precipitate a low melting point NiS compound at the weld metal grain boundaries. This is because the ductility of the grain boundaries of the steel is deteriorated, which in turn adversely affects the hot cracking resistance to welding.
Ｃａ、Ｍｇ、ＲＥＭは、前述のように、耐食性をより向上させる効果がある。即ち、腐食先端部のｐＨ低下を抑制する作用や、孔食の起点となり耐候性を低下させるＭｎＳの生成を抑制する働き、および、腐食初期にＺｎとＦｅを安定的に腐食させる効果がある。更に、Ｃａには溶接性の向上効果もある。As described above, Ca, Mg, and REM have an effect of further improving the corrosion resistance. That is, it has the effect of suppressing the decrease in pH at the corrosion tip, the function of suppressing the generation of MnS that becomes the starting point of pitting corrosion and lowers the weather resistance, and the effect of stably corroding Zn and Fe in the early stage of corrosion. Furthermore, Ca also has an effect of improving weldability.
Ｃａ：０．０００５〜０．００５０質量％としているのは、Ｃａ：０．０００５質量％未満の場合、耐食性向上効果が不充分となり、Ｃａ：０．００５０質量％超の場合、耐食性向上効果は飽和し、経済的ではなく、また、鋼の清浄度を悪くし、更に、耐候性鋼材の製造時、特に製鋼中の炉壁を損傷する可能性もあるからである。Ca: 0.0005 to 0.0050% by mass is sufficient when Ca is less than 0.0005% by mass, and the effect of improving corrosion resistance is insufficient. When Ca is over 0.0050% by mass, the effect of improving corrosion resistance is This is because it is saturated and is not economical, and the cleanliness of the steel is deteriorated, and further, during the production of the weather-resistant steel, there is a possibility of damaging the furnace wall especially during steelmaking.
Ｍｇ：０．０００５〜０．０１０質量％としているのは、Ｍｇ：０．０００５質量％未満の場合、耐食性向上効果が不充分となり、Ｍｇ：０．０１０質量％超の場合、耐食性向上効果は飽和し、経済的ではなく、また、鋼の清浄度を悪くするからである。Mg: 0.0005 to 0.010% by mass, if Mg is less than 0.0005% by mass, the effect of improving corrosion resistance is insufficient, and if Mg: more than 0.010% by mass, the effect of improving corrosion resistance is This is because it is saturated and not economical, and deteriorates the cleanliness of the steel.
ＲＥＭ：０．０００５〜０．０１０質量％としているのは、ＲＥＭ：０．０００５質量％未満の場合、耐食性向上効果が不充分となり、ＲＥＭ：０．０１０質量％超の場合、耐食性向上効果は飽和し、経済的ではなく、また、鋼の機械的性質も悪くなるからである。REM: 0.0005 to 0.010% by mass means that when REM: less than 0.0005% by mass, the effect of improving corrosion resistance is insufficient, and when REM: more than 0.010% by mass, the effect of improving corrosion resistance is This is because it is saturated and not economical, and the mechanical properties of steel are also deteriorated.
以上の点に鑑みて、本発明の第１発明に係る鋼材は、Ｃ：０．０２〜０．２０質量％、Ｍｎ：０．１〜２．５質量％、Ｓｉ：０．０３〜１．０質量％、Ａｌ：０．０３〜０．５質量％、Ｔｉ：０．０１〜０．１質量％、Ｐ：０．１質量％以下、Ｓ：０．００５質量％以下、Ｃｒ：０．５質量％以下、Ｚｎ：０．０１〜３．０質量％、Ｃｕ：０．０５〜３．０質量％、Ｎｉ：０．０５〜６．０質量％を含有し、更に、Ｃａ：０．０００５〜０．００５０質量％、Ｍｇ：０．０００５〜０．０１０質量％、ＲＥＭ：０．０００５〜０．０１０質量％のいずれか１種または２種以上を含有し、残部Ｆｅおよび不可避的不純物からなることを特徴とするものとした。 In view of the above points, the steel material according to the first invention of the present invention has C: 0.02 to 0.20 mass%, Mn: 0.1 to 2.5 mass%, Si: 0.03 to 1. 0% by mass, Al: 0.03-0.5% by mass, Ti: 0.01-0.1% by mass, P: 0.1% by mass or less, S: 0.005% by mass or less, Cr: 0.00%. 5 mass% or less , Zn: 0.01-3.0 mass%, Cu: 0.05-3.0 mass%, Ni: 0.05-6.0 mass%, and Ca: 0.0. 0005 to 0.0050 mass%, Mg: 0.0005 to 0.010 mass%, REM: 0.0005 to 0.010 mass%, any one or two or more of the remaining Fe and unavoidable impurities It is characterized by comprising.
以上の本発明に係る鋼材（第１発明）において、更にＮｂ：０．００５〜０．１０質量％、Ｖ：０．０１〜０．２０質量％、Ｚｒ：０．００５〜０．１０質量％、Ｍｏ：０．１〜１．０質量％、Ｂ：０．０００３〜０．００３０質量％のいずれか１種または２種以上を含有するようにすると、更に耐食性が向上する〔第２発明〕。Ｎｂ、Ｖ、Ｚｒ、Ｍｏ、Ｂは保護性さび生成促進の効果がある。なお、Ｎｂ、Ｖには焼き入性を上昇させ、強度を増加する効果もある。また、Ｂは焼き入性を上昇させる効果もある。 In steel (first invention) according to the present invention described above, further Nb: 0.005 to 0.10 mass%, V: 0.01 to 0.20 wt%, Zr: 0.005 to 0.10 wt% , Mo: 0.1 to 1.0% by mass, B: 0.0003 to 0.0030% by mass, and the inclusion of one or more of them further improves the corrosion resistance [ second invention]. . Nb, V, Zr, Mo, and B have the effect of promoting the generation of protective rust. Nb and V also have the effect of increasing hardenability and increasing strength. B also has the effect of increasing hardenability.
本発明においてＣｕ、Ｎｉ濃化層は鋼材表面に耐食性向上元素のＣｕおよびＮｉが濃化した層であり、ＣｕおよびＮｉ濃度が高いので、前述のように耐食性を向上させる。このＣｕ、Ｎｉ濃化層は、このように耐食性を向上させるだけでなく、表面の割れ発生を抑制し、結果的に溶接部の靭性を向上させる利点があることもわかった。 In the present invention, the Cu and Ni concentrated layers are layers in which the corrosion resistance improving elements Cu and Ni are concentrated on the surface of the steel material. Since the Cu and Ni concentrations are high, the corrosion resistance is improved as described above. It has also been found that this Cu and Ni concentrated layer not only improves the corrosion resistance in this way, but also has the advantage of suppressing the occurrence of cracks on the surface and consequently improving the toughness of the weld.
このＣｕ、Ｎｉ濃化層が、鋼材最表面から深さ５００μｍまでの領域に、Ｃｕ量＋Ｎｉ量：鋼材のＣｕ量＋Ｎｉ量の１．２倍以上、且つ、１．０質量％以上であると共に、厚さ：１μｍ以上である場合、即ち、鋼材最表面から深さ５００μｍまでの領域に、Ｃｕ量＋Ｎｉ量が鋼材のＣｕ量＋Ｎｉ量の１．２倍以上であり、且つ、１．０質量％以上であるＣｕ＋Ｎｉ濃化層（Ｃｕ、Ｎｉ濃化層）を有し、その濃化層の厚さが１μｍ以上である場合は、より確実に、耐食性を向上させることができる〔第３発明〕。 This Cu and Ni concentrated layer is in a region from the outermost surface of the steel material to a depth of 500 μm, with Cu amount + Ni amount: 1.2 times or more of steel material Cu amount + Ni amount and 1.0% by mass or more. When the thickness is 1 μm or more, that is, in the region from the steel outermost surface to a depth of 500 μm, the Cu amount + Ni amount is 1.2 times or more of the Cu amount + Ni amount of the steel material and 1.0 mass % Of Cu + Ni concentrated layer (Cu, Ni concentrated layer) and the thickness of the concentrated layer is 1 μm or more, the corrosion resistance can be improved more reliably [ Third Invention ].
なお、上記鋼材のＣｕ量＋Ｎｉ量としては、厳密には母材の中心厚さにおけるＣｕ量＋Ｎｉ量を用いることが望ましいが、Ｃｕ、Ｎｉ濃化層およびその付近を除いた個所でのＣｕ量＋Ｎｉ量を用いてもよく、また、表面に腐食や溶解が全く生じていない鋼材を用いて通常の分析法で分析した場合はその分析値に基づいて求めたＣｕ量＋Ｎｉ量を用いてもよい。 Strictly speaking, it is desirable to use the Cu amount + Ni amount in the center thickness of the base material as the Cu amount + Ni amount of the steel material. However, the Cu amount in the portion excluding the Cu, Ni concentrated layer and its vicinity. + Ni amount may be used, and when analysis is performed by a normal analysis method using a steel material having no corrosion or dissolution on the surface, the Cu amount + Ni amount obtained based on the analysis value may be used. .
Ｃｕ、Ｎｉ濃化層のＣｕ量＋Ｎｉ量と厚みの測定は、例えば、ＥＰＭＡ（Ｘ線マイクロアナリシス）により行うことができ、この場合、具体的には試験片断面をＥＰＭＡにより表面から深さ５００μｍまでの領域について元素分析を行うと共に、板厚中心部の元素分析を行い、これによりＣｕ、Ｎｉ濃化層のＣｕ量＋Ｎｉ量と厚みを求めることができる。このとき、分析個所数は例えば10点とし、その平均値を用いる。 Measurement of Cu amount + Ni amount and thickness of Cu and Ni concentrated layer can be performed by, for example, EPMA (X-ray microanalysis). In this case, specifically, the cross section of the test piece is 500 μm deep from the surface by EPMA. In addition to performing elemental analysis up to this region, elemental analysis at the center of the plate thickness is performed, whereby the Cu amount + Ni amount and thickness of the Cu and Ni concentrated layer can be determined. At this time, the number of analysis points is, for example, 10 points, and the average value is used.
耐候性に対しては通常範囲の１０μｍ程度の細粒化ではほとんど効果がないが、平均粒径が５μｍ以下の超細粒組織とすることにより、耐食性が向上する。特に、亜鉛による溶解作用が効力を発揮するだけでなく、耐食性向上に寄与する安定さびの形成も均一化されて、耐候性が飛躍的に向上する。望ましくは、３μｍ以下、サブμｍであれば更に良い。本発明の成分・組織から形成される安定さびは、塩化物環境下でとくに性能を発揮し、塩化物環境下で生成し、耐食性を劣化させるベータさびの生成を抑制する機能があるので、裸での使用で優れた耐食性を発揮する。また、塗装使用にても塗膜下腐食を大幅に抑制する。 Although there is little effect on the weather resistance when the grain size is reduced to about 10 μm in the normal range, the corrosion resistance is improved by using an ultrafine grain structure having an average particle size of 5 μm or less. In particular, the dissolution effect by zinc not only exhibits its effectiveness, but also the formation of stable rust contributing to the improvement of corrosion resistance is made uniform, and the weather resistance is dramatically improved. Desirably, 3 μm or less and sub μm are even better. The stable rust formed from the components / structures of the present invention exhibits a performance particularly in a chloride environment and has a function of suppressing the formation of beta rust which is generated in a chloride environment and deteriorates corrosion resistance. Excellent corrosion resistance when used in Moreover, even under coating, corrosion under the coating film is greatly suppressed.
耐食性向上には粒径だけでなく、組織も影響する。望ましくは、フェライトが５０％以上を占め、フェライト以外の第二相で耐食性に悪影響を及ぼすパーライト、ベイナイト、マルテンサイト相は面積率で２５％以下にするのが望ましい。 Improvement in corrosion resistance affects not only the particle size but also the structure. Desirably, ferrite accounts for 50% or more, and the pearlite, bainite, and martensite phases that adversely affect the corrosion resistance in the second phase other than ferrite are desirably 25% or less in terms of area ratio.
鋼板において、このような平均粒径が５μｍ以下であって、組織に占めるフェライトの面積率が５０％以上、フェライト以外の第二相の面積率が２５％以下の微細組織を有すべき領域は、鋼板の表裏面のそれぞれの表面から板厚方向に板厚の１０％〜３０％の領域である。耐食性の観点からは板厚中心部まで細粒化してもかまわないが、少なくとも表層部の細粒化が必要である。なお、鋼板の表裏面のそれぞれの表面から板厚方向に板厚の１０〜３０％の領域とは、鋼板の表側最表面から板厚方向に板厚の１０％入った位置から３０％入った位置までの領域（板厚の１０％位置と３０％位置との間の領域）、及び、鋼板の裏側最表面から板厚方向に板厚の１０％入った位置から３０％入った位置までの領域（板厚の１０％位置と３０％位置との間の領域）のことである。 In the steel sheet, such an average grain size is 5 μm or less, the area ratio of ferrite occupying the structure is 50% or more, and the area ratio of the second phase other than ferrite should have a fine structure of 25% or less. The region of 10% to 30% of the plate thickness in the plate thickness direction from the respective front and back surfaces of the steel plate. From the standpoint of corrosion resistance, it may be finer up to the center of the plate thickness, but at least the surface layer must be finer. The region of 10-30% of the plate thickness in the plate thickness direction from the respective front and back surfaces of the steel plate was 30% from the position where 10% of the plate thickness was entered in the plate thickness direction from the top surface of the steel plate. The region up to the position (region between the 10% position and 30% position of the plate thickness), and the position from 10% of the plate thickness in the plate thickness direction to the position of 30% from the back side outermost surface of the steel plate It is an area (area between 10% position and 30% position of the plate thickness).
かかる点に鑑みて、本発明の第４発明に係る鋼材は、本発明に係る鋼材（第１発明または第２〜３発明のいずれか）において、鋼材が鋼板であって、この鋼板の表裏面のそれぞれの表面から板厚方向に板厚の１０％〜３０％の領域（以下、特定領域ともいう）における平均フェライト粒径が５μｍ以下であるものとした。この鋼材（鋼板）は、上記特定領域における平均フェライト粒径が５μｍ超のものよりも、耐食性が優れている。なお、上記特定領域における平均フェライト粒径とは、上記特定領域に存するフェライトの平均粒径のことである。この平均粒径が５μｍ以下であるフェライトの面積率が５０％以上であると、さらに高水準で耐食性に優れたものとなる。 In view of this point, the steel material according to the fourth invention of the present invention is a steel material according to the present invention (any of the first invention or the second to third inventions), wherein the steel material is a steel plate, and the front and back surfaces of this steel plate. The average ferrite particle size in the region of 10% to 30% of the plate thickness (hereinafter also referred to as a specific region) in the plate thickness direction from the respective surfaces of the steel sheets was 5 μm or less. This steel material (steel plate) has better corrosion resistance than that having an average ferrite particle size of more than 5 μm in the specific region. The average ferrite particle size in the specific region is the average particle size of ferrite existing in the specific region. When the area ratio of the ferrite having an average particle size of 5 μm or less is 50% or more, the corrosion resistance is further improved at a higher level.
このような鋼板の製造手段については、特には限定されず、種々の手段を用いることができるが、好ましい手段として、フェライト単相域〜フェライト／オーステナイト二相域で熱間加工を行ってフェライトに加工歪を導入し、フェライトの再結晶を利用する方法が挙げられる。 The means for producing such a steel sheet is not particularly limited, and various means can be used. However, as a preferable means, hot working is performed in a ferrite single phase region to a ferrite / austenite two phase region to obtain a ferrite. There is a method of introducing processing strain and utilizing recrystallization of ferrite.
本発明に係る鋼材の適用の形態については、特には限定されず、例えば、熱間圧延した鋼板、冷間圧延した鋼板、または、熱延あるいは冷延を行った後に焼鈍を施した鋼板に、化成処理、溶融めっき、電気めっき、蒸着などのめっきや、各種塗装、塗装下地処理、有機被膜処理などを行って用いることも可能である。 The form of application of the steel material according to the present invention is not particularly limited, for example, a hot-rolled steel sheet, a cold-rolled steel sheet, or a steel sheet subjected to annealing after hot rolling or cold rolling, It is also possible to use after performing chemical conversion treatment, hot dip plating, electroplating, vapor deposition, etc., various coatings, paint base treatment, organic coating treatment, and the like.
塗装の場合、各種用途に応じてリン酸塩処理などの化成処理を施したり、電着塗装を施してもよい。塗料は公知の樹脂が使用可能であり、エポキシ樹脂、フッ素樹脂、シリコンアクリル樹脂、ポリウレタン樹脂、アクリル樹脂、ポリエステル樹脂、フェノール樹脂、アルキッド樹脂、メラミン樹脂などを公知の硬化剤とともに使用可能である。特に、耐食性の観点からすればエポキシ、フッ素、シリコンアクリル樹脂の使用が推奨される。その他、塗料に添加される公知の添加剤、例えば着色用顔料、カップリング剤、レベリング剤、増感剤、酸化防止剤、紫外線安定剤、難燃剤などを添加してもよい。 In the case of coating, chemical conversion treatment such as phosphate treatment or electrodeposition coating may be performed according to various applications. A known resin can be used as the paint, and an epoxy resin, a fluororesin, a silicon acrylic resin, a polyurethane resin, an acrylic resin, a polyester resin, a phenol resin, an alkyd resin, a melamine resin, and the like can be used together with a known curing agent. In particular, from the viewpoint of corrosion resistance, it is recommended to use epoxy, fluorine, or silicon acrylic resin. In addition, known additives added to the paint, such as coloring pigments, coupling agents, leveling agents, sensitizers, antioxidants, UV stabilizers, flame retardants, and the like may be added.
また、塗料形態も特に限定されず、溶剤系塗料、粉体塗料、水系塗料、水分散型塗料、電着塗料など、用途に応じて適宜選択することができる。 Also, the form of the paint is not particularly limited, and can be appropriately selected according to the use such as solvent-based paint, powder paint, water-based paint, water-dispersed paint, and electrodeposition paint.
上記塗料を用い、所望の被覆層を鋼材に形成させるには、ディッピング法、ロールコータ法、スプレー法、カーテンフローコーター法などの公知の方法を用いればよい。被覆層の厚みは用途に応じて公知の適切な値を用いればよい。 In order to form a desired coating layer on a steel material using the coating material, a known method such as a dipping method, a roll coater method, a spray method, or a curtain flow coater method may be used. The thickness of the coating layer may be a known appropriate value depending on the application.
Ｃｕ、Ｎｉ濃化層を早期に形成させるために、腐食促進処理（濃化促進処理）を施してもよい。かかる処理としては、ｐＨ７未満の酸性の腐食溶液を塗布する方法が望ましい。例えば、特開平１１−２４１１７２号公報に記載されているような表面に、Ti、Nb、Ta、Zr、V 、Hfの硫酸塩を含む水溶液、および、これらに加えてCr、Ni、Cu、P の硫酸塩を含む水溶液を鋼材表面に塗布する処理が望ましい。要求されるレベルに応じて、酸溶液の濃度、処理時間を変化させ、所望の濃化層を形成させればよい。 In order to form a Cu and Ni concentrated layer at an early stage, a corrosion promotion treatment (concentration promotion treatment) may be performed. As such treatment, a method of applying an acidic corrosive solution having a pH of less than 7 is desirable. For example, an aqueous solution containing sulfates of Ti, Nb, Ta, Zr, V, and Hf on the surface as described in JP-A-11-241172, and in addition to these, Cr, Ni, Cu, P It is desirable to apply an aqueous solution containing the above sulfate to the steel surface. According to the required level, the concentration of the acid solution and the treatment time may be changed to form a desired concentrated layer.
本発明の実施例および比較例を以下説明する。なお、本発明はこの実施例に限定されるものではなく、本発明の趣旨に適合し得る範囲で適当に変更を加えて実施することも可能であり、それらはいずれも本発明の技術的範囲に含まれる。 Examples of the present invention and comparative examples will be described below. The present invention is not limited to this embodiment, and can be implemented with appropriate modifications within a range that can be adapted to the gist of the present invention, all of which are within the technical scope of the present invention. include.
〔例Ａ〕
表１に示す化学成分の鋼板を供試材とした。この供試材より試験片を作製し、これを用いて耐食性評価試験および耐孔あき性評価試験を行い、耐食性および耐孔あき性を評価した。なお、 No.４の鋼材は熱間割れを生じたため、これらの試験はできなかった。
[Example A]
Steel sheets having chemical components shown in Table 1 were used as test materials. A test piece was prepared from the test material, and a corrosion resistance evaluation test and a perforation resistance evaluation test were performed using the test piece to evaluate the corrosion resistance and the perforation resistance. Since the steel No. 4 had hot cracks, these tests could not be performed.
耐食性評価試験としては、兵庫県内の暴露試験場において試験片を暴露する試験を行った。この試験は、より詳細には、試験片表面をサンドブラスト処理後、南向きで一年間暴露（加えて、週一回の塩水を強制散布）するという試験である。この耐食性評価試験後、試験片表面の錆を除去し、板厚減少量から耐食性を評価した。 As a corrosion resistance evaluation test, a test was conducted to expose a test piece at an exposure test site in Hyogo Prefecture. More specifically, this test is a test in which the surface of the test piece is subjected to sandblasting and then exposed southward for one year (plus forced spraying of salt water once a week). After this corrosion resistance evaluation test, the rust on the surface of the test piece was removed, and the corrosion resistance was evaluated from the reduction in thickness.
耐孔あき性評価試験は、下記試験により行った。即ち、試験片にリン酸塩処理を施した後、カチオン電着塗装（２０ミクロン狙い）を行い、鋼材素地に達するクロスカットを施し、ＣＣＴ試験〔塩水散布→乾燥→湿潤のサイクルを繰り返す（１日１サイクル）〕を３０日（３０サイクル）行った。この耐孔あき性評価試験後、評価面を等間隔に１６区画に分割して、各区画ごとに最大孔あき深さを測定し、その平均値を算出し、耐孔あき性を評価した。 The perforation resistance evaluation test was performed by the following test. That is, after subjecting the test piece to phosphate treatment, cationic electrodeposition coating (targeting 20 microns) is performed, cross-cut reaching the steel substrate is performed, and the CCT test [salt water spraying → drying → wetting cycle is repeated (1 1 cycle per day)] for 30 days (30 cycles). After this perforation resistance evaluation test, the evaluation surface was divided into 16 sections at equal intervals, the maximum perforation depth was measured for each section, the average value was calculated, and the perforation resistance was evaluated.
また、 No.１、２、９、１０の鋼材を用いて溶接を行い、溶接部の靱性を評価した。このとき、溶接は入熱量35KJ/cm のサブマージアーク溶接法により行った。溶接部の靱性は溶接継手ボンド部の−40℃における吸収エネルギー:vE-40（Ｎ／mm2 ）で評価した。 Moreover, welding was performed using the steel materials No. 1, 2, 9, and 10, and the toughness of the welded portion was evaluated. At this time, welding was performed by a submerged arc welding method with a heat input of 35 KJ / cm 2. The toughness of the welded portion was evaluated by the absorbed energy at −40 ° C. of the welded joint bond portion: vE-40 (N / mm 2 ).
耐食性評価試験および耐孔あき性評価試験試験結果については下記のようにして評価した。即ち、 No.１（比較鋼１）の腐食量Ｂを基準にし、腐食量が腐食量Ｂの７０％未満のものを◎◎（極めて優れる水準）、腐食量Ｂの７０％以上７５％未満のものを◎（優れる水準）、腐食量Ｂの７５％以上８０％未満のものを○（良好）、腐食量Ｂの８０％以上８５％未満のものを△（不良）、腐食量Ｂの８５％以上９０％未満のものを×（不良）、腐食量Ｂの９０％以上のものを××（極めて不良）とした。なお、上記腐食量は、耐食性評価試験の場合は板厚減少量であり、耐孔あき性評価試験の場合は各区画の最大孔あき深さの平均値である。 The results of the corrosion resistance evaluation test and the perforation resistance evaluation test were evaluated as follows. That is, based on the corrosion amount B of No. 1 (Comparative Steel 1), the corrosion amount is less than 70% of the corrosion amount B (excellent level), and the corrosion amount B is 70% or more and less than 75%. ◎ (excellent level), 75% to less than 80% of corrosion amount B (good), 80% to less than 85% corrosion amount B (bad), 85% of corrosion amount B More than 90% of the samples were evaluated as x (defect), and 90% or more of the corrosion amount B was determined as xx (very poor). The corrosion amount is the thickness reduction amount in the case of the corrosion resistance evaluation test, and is the average value of the maximum perforation depth of each section in the case of the perforation resistance evaluation test.
暴露試験後の試験片の断面をＥＰＭＡ（Ｘ線マイクロアナリシス）により表層部および板厚中心部の元素分析を１０点行い、各々平均値を求めた。この結果からＣｕ量＋Ｎｉ量を求め、この値からＣｕ量＋Ｎｉ量：１．０質量％以上のＣｕ、Ｎｉ濃化層の厚さを求めた。また、Ｃｕ、Ｎｉ濃化層のＣｕ量＋Ｎｉ量／板厚中心部のＣｕ量＋Ｎｉ量（Ｃｕ＋Ｎｉ濃度比）を求めた。 The cross section of the test piece after the exposure test was subjected to elemental analysis of the surface layer part and the plate thickness center part by EPMA (X-ray microanalysis), and the average value was obtained for each. From this result, the Cu amount + Ni amount was obtained, and from this value, the Cu amount + Ni amount: the thickness of the Cu and Ni concentrated layer of 1.0 mass% or more was obtained. Further, Cu amount of Cu and Ni concentrated layer + Ni amount / Cu amount at center of plate thickness + Ni amount (Cu + Ni concentration ratio) were obtained.
この結果を表２に示す。 No.１、２、３、４、５、６、７は、いずれも比較例に係る鋼材である。 No.１に係る鋼材は、Ｃｕフリー、Ｎｉフリー、Ｚｎフリーであると共に、Ｃａ、Ｍｇ、ＲＥＭフリー（いずれも無添加）であり、これらの点において本発明の要件を満たしていない。 No.２に係る鋼材は、Ｎｉフリーであると共にＣａ、Ｍｇ、ＲＥＭフリーであり、且つ、Ｚｎ量およびＣｕ量が本発明の場合より少なく、これらの点において本発明の要件を満たしていない。 No.３に係る鋼材は、Ｃｕフリーであると共にＣａ、Ｍｇ、ＲＥＭフリーであり、且つ、Ｚｎ量およびＮｉ量が本発明の場合より少なく、これらの点において本発明の要件を満たしていない。 No.４に係る鋼材は、Ｚｎフリーであると共にＣａ、Ｍｇ、ＲＥＭフリーであり、且つ、Ｃｕ量が本発明の場合より多く、これらの点において本発明の要件を満たしていない。 No.５に係る鋼材は、Ｃａ、Ｍｇ、ＲＥＭフリーであると共に、Ｚｎ量が本発明の場合より多い点において本発明の要件を満たしていない。 No.６に係る鋼材は、Ｚｎ量が本発明の場合より少ない点において本発明の要件を満たしていない。 No.７に係る鋼材は、Ｃａ、Ｍｇ、ＲＥＭフリーである点において本発明の要件を満たしていない。 The results are shown in Table 2. Nos. 1, 2, 3, 4, 5, 6, and 7 are all steel materials according to comparative examples. The steel material according to No. 1 is Cu-free, Ni-free, and Zn-free, and is Ca, Mg, and REM-free (no addition), and does not satisfy the requirements of the present invention in these respects. The steel material according to No. 2 is Ni-free and Ca, Mg, and REM-free, and has a smaller amount of Zn and Cu than in the present invention, and does not satisfy the requirements of the present invention in these respects. The steel material according to No. 3 is Cu-free and Ca-, Mg-, and REM-free, and has a smaller amount of Zn and Ni than in the present invention, and does not satisfy the requirements of the present invention in these respects. The steel material according to No. 4 is Zn-free and Ca, Mg, REM-free, and has a larger amount of Cu than in the present invention, and does not satisfy the requirements of the present invention in these respects. The steel material according to No. 5 is free of Ca, Mg, and REM, and does not satisfy the requirements of the present invention in that the amount of Zn is larger than that in the case of the present invention. The steel material according to No. 6 does not satisfy the requirements of the present invention in that the amount of Zn is smaller than that of the present invention. The steel material according to No. 7 does not satisfy the requirements of the present invention in that it is Ca, Mg, and REM free.
No.８、９、１０、１１、１２、１３、１４は、いずれも本発明の実施例に係る鋼材である。この中、 No.１１、１２、１３、１４は、Ｂ、Ｍｏ、Ｚｒ、Ｎｂも含有し、それらの量は第２発明で規定する量を満たしており、従って、第２発明の要件を満たすものである。 Nos. 8, 9, 10, 11, 12, 13, and 14 are all steel materials according to examples of the present invention. Among them, Nos. 11, 12, 13, and 14 also contain B, Mo, Zr, and Nb, and their amounts satisfy the amount specified in the second invention, and therefore satisfy the requirements of the second invention. Is.
表２からわかるように、本発明の実施例に係る鋼材（ No.８、９、１０、１１、１２、１３、１４）は、比較例に係る鋼材（ No.１、２、３、４、５、６、７）に比べて、耐食性および耐孔あき性が優れている。 As can be seen from Table 2, the steel materials (No. 8, 9, 10, 11, 12, 13, 14) according to the examples of the present invention are the steel materials (No. 1, 2, 3, 4, Compared to 5, 6, 7), the corrosion resistance and the perforation resistance are excellent.
なお、上記 No.１〜１４の鋼材（鋼板）の特定領域（鋼板の表裏面のそれぞれの表面から板厚方向に板厚の１０％〜３０％の領域）における平均フェライト粒径は、鋼板の表面側（鋼板の表側最表面から板厚の１０％位置と３０％位置との間の領域）で２２〜２３μｍであり、鋼板の裏面側（鋼板の裏側最表面から板厚の１０％位置と３０％位置との間の領域）で２２〜２３μｍであった。この領域におけるフェライトの面積率は７０〜９０％であった。この粒径の測定は、鋼板の上記領域について倍率２００〜５０００倍の走査型電子顕微鏡で５〜１０視野観察することにより行った。 In addition, the average ferrite particle diameter in the specific area | region (The area | region of 10%-30% of board thickness to the board thickness direction from each surface of the front and back surfaces of a steel sheet) of the steel materials (steel board) of No. 1-14 is the steel sheet. It is 22-23 μm on the front side (region between the 10% position and 30% position of the plate thickness from the outermost surface of the steel plate), and the back side of the steel plate (10% position of the plate thickness from the outermost surface of the steel plate) The region between 30% position) was 22-23 μm. The area ratio of ferrite in this region was 70 to 90%. The measurement of the particle size was performed by observing 5 to 10 fields of view with a scanning electron microscope having a magnification of 200 to 5000 in the above-described region of the steel sheet.
〔例Ｂ〕
表３に示す化学成分の鋼を供試材として、フェライト単相域〜フェライト／オーステナイト二相域で熱間加工を行ってフェライトに加工歪を導入し、フェライトの再結晶を利用することにより、細粒化した鋼板を得た。この鋼板について、鋼板の特定領域（鋼板の表裏面のそれぞれの表面から板厚方向に板厚の１０％〜３０％の領域）における平均フェライト粒径を測定した。この粒径の測定は、鋼板の上記領域について倍率２００〜５０００倍の走査型電子顕微鏡で５〜１０視野観察することにより行った。
[Example B]
By using steel of chemical composition shown in Table 3 as a test material, hot working in a ferrite single phase region to a ferrite / austenite two phase region to introduce work strain into the ferrite, and utilizing recrystallization of ferrite, A refined steel sheet was obtained. About this steel plate, the average ferrite particle size in a specific region of the steel plate (region of 10% to 30% of the plate thickness in the plate thickness direction from the respective front and back surfaces of the steel plate) was measured. The measurement of the particle size was performed by observing 5 to 10 fields of view with a scanning electron microscope having a magnification of 200 to 5000 in the above-described region of the steel sheet.
また、上記鋼板について、耐食性評価試験および耐孔あき性評価試験を行った。この試験は、前記例Ａの場合と同様の方法により行った。この結果については、下記のようにして評価した。即ち、前述の例Ａの表１〜２の No.１（比較鋼１）の腐食量Ｂを基準にし、腐食量が腐食量Ｂの６０％未満のものを◎◎◎〔極めて優れる水準（後述の◎◎よりも優れる水準）〕、腐食量が腐食量Ｂの７０％未満のものを◎◎（極めて優れる水準）、腐食量Ｂの７０％以上７５％未満のものを◎（優れる水準）、腐食量Ｂの７５％以上８０％未満のものを○（良好）、腐食量Ｂの８０％以上８５％未満のものを△（不良）、腐食量Ｂの８５％以上９０％未満のものを×（不良）、腐食量Ｂの９０％以上のものを××（極めて不良）とした。 Further, the steel sheet was subjected to a corrosion resistance evaluation test and a perforation resistance evaluation test. This test was performed in the same manner as in Example A above. This result was evaluated as follows. That is, based on the corrosion amount B of No. 1 (Comparative Steel 1) in Tables 1 and 2 of Example A described above, the corrosion amount is less than 60% of the corrosion amount B. ◎◎ (corresponding to a level superior to ◎◎)), the amount of corrosion being less than 70% of the corrosion amount B ◎◎ (very superior level), the amount of corrosion being 70% or more and less than 75% ◎ (excellent level), Corrosion amount B of 75% or more and less than 80% ○ (good), corrosion amount B of 80% or more and less than 85% △ (bad), corrosion amount B of 85% or more and less than 90% × (Poor), 90% or more of the corrosion amount B was defined as xx (very bad).
この結果を表４に示す。 No.15-1、15-2、15-3、15-4は、いずれも本発明例に係る鋼板である。この中、 No.15-2、15-3、15-4は、鋼板の特定領域における平均フェライト粒径が５μｍ以下であり、第４発明の要件を満たすものである。 The results are shown in Table 4. Nos. 15-1, 15-2, 15-3, and 15-4 are all steel plates according to examples of the present invention. Among these, Nos. 15-2, 15-3, and 15-4 have an average ferrite grain size of 5 μm or less in a specific region of the steel sheet and satisfy the requirements of the fourth invention.
表４からわかるように、 No.15-2、15-3、及び、15-4の鋼板（第４発明の要件を満たしている）は、No.15-1 の鋼板（第４発明の要件を満たしていない）に比較して、上記領域での平均フェライト粒径が小さく、耐食性に優れている。 No.15-2、15-3、及び、15-4の鋼板において、上記特定領域での平均フェライト粒径が小さい場合ほど、耐食性が向上している。 As can be seen from Table 4, No.15-2, 15-3, and 15-4 steel plates (which meet the requirements of the fourth invention) are No.15-1 steel plates (requirements of the fourth invention) The average ferrite particle size in the above region is small and the corrosion resistance is excellent. In the steel plates No. 15-2, 15-3, and 15-4, the smaller the average ferrite grain size in the specific region, the better the corrosion resistance.
表４において、No.15-4Zの鋼板は、No.15-4 の鋼板の表側表面および裏側表面から研削をして細粒化している部分を取り除いたものである。このNo.15-4Zの鋼板の特定領域での平均フェライト粒径はNo.15-4 の鋼板の場合よりも極めて大きく、耐食性がNo.15-4 の鋼板の場合よりも劣っている。 In Table 4, the No. 15-4Z steel plate is obtained by removing the finely divided portions by grinding from the front and back surfaces of the No. 15-4 steel plate. The average ferrite grain size in a specific region of this No. 15-4Z steel plate is much larger than that of the No. 15-4 steel plate, and the corrosion resistance is inferior to that of the No. 15-4 steel plate.
これらの結果より、鋼板の表層の細粒化部分の耐食性向上効果が大きいことがよくわかる。耐食性向上の観点からは板厚中心部まで細粒化することが望ましいが、実環境上の腐食代と製造上の経済性を考慮して必要分（鋼板の特定領域）を細粒化すればよい。 These results clearly show that the effect of improving the corrosion resistance of the refined portion of the surface layer of the steel sheet is great. From the viewpoint of improving corrosion resistance, it is desirable to make the grain finer to the center of the plate thickness. However, if the necessary part (specific area of the steel sheet) is made finer in consideration of the corrosion allowance in the actual environment and the economics of manufacturing. Good.
なお、No.15-1 、15-2、15-3、15-4、15-4Z の鋼板の特定領域におけるフェライトの面積率は８０〜９０％であった。 In addition, the area ratio of the ferrite in the specific area | region of No.15-1, 15-2, 15-3, 15-4, 15-4Z steel plate was 80 to 90%.
以上の例は代表的なものであって、以上の例での効果は上記試験環境に限定されるものではない。 The above examples are representative, and the effects in the above examples are not limited to the above test environment.
本発明に係る高耐食性鋼材は、耐食性向上元素の過剰な添加による機械的特性および溶接性の低下をきたすことなく、優れた耐食性を有することができるので、橋梁や、船舶、海洋構造物、他鋼構造物、建材、家電、自動車等の構成材料として好適に用いることができ、それらの耐久性を向上することができて有用である。 Since the high corrosion resistance steel material according to the present invention can have excellent corrosion resistance without causing deterioration of mechanical properties and weldability due to excessive addition of an element for improving corrosion resistance, it can be used for bridges, ships, marine structures, etc. It can be suitably used as a constituent material for steel structures, building materials, home appliances, automobiles, etc., and is useful because it can improve the durability thereof.
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| JP2005331956A JP4495668B2 (en) | 2004-11-19 | 2005-11-16 | High corrosion resistance steel |
| TW095108618A TW200720449A (en) | 2004-11-19 | 2006-03-14 | Highly corrosion resistant steel |
| CN200610059680XA CN1966754B (en) | 2004-11-19 | 2006-03-17 | Highly corrosion resistant steel |
| KR1020060025373A KR100810319B1 (en) | 2004-11-19 | 2006-03-20 | Steel material having a high errosion resistant property |
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| JP5065700B2 (en) * | 2007-02-09 | 2012-11-07 | 株式会社神戸製鋼所 | Steel sheet with excellent cutting performance |
| JP4898543B2 (en) * | 2007-05-02 | 2012-03-14 | 株式会社神戸製鋼所 | Steel sheet with excellent pit resistance and method for producing the same |
| JP5396758B2 (en) * | 2007-07-27 | 2014-01-22 | Ｊｆｅスチール株式会社 | Hot-rolled section steel for ship ballast tank and manufacturing method thereof |
| JP5155097B2 (en) * | 2008-10-21 | 2013-02-27 | 株式会社神戸製鋼所 | Steel used for containers containing minerals |
| CN103451537B (en) * | 2013-08-16 | 2016-04-27 | 江苏省沙钢钢铁研究院有限公司 | Low-temperature weather-resistant steel plate with high welding performance and production method thereof |
| CN103667917A (en) * | 2013-11-08 | 2014-03-26 | 铜陵安东铸钢有限责任公司 | High-temperature-resistant low-carbon steel material and preparation method thereof |
| CN104593641A (en) * | 2014-05-23 | 2015-05-06 | 无锡市乾丰锻造有限公司 | Novel high-strength iron-aluminum alloy forging material |
| CN104613437A (en) * | 2015-02-10 | 2015-05-13 | 浙江兰普防爆照明有限公司 | Anti-corrosion LED radiator |
| CN105349883A (en) * | 2015-12-07 | 2016-02-24 | 张家港市新凯带钢制造有限公司 | Corrosion-resistant alloy steel |
| CN105506456A (en) * | 2015-12-24 | 2016-04-20 | 芜湖恒耀汽车零部件有限公司 | Exhaust pipe of composite material and preparation method of exhaust pipe |
| CN105886944A (en) * | 2016-06-23 | 2016-08-24 | 温州德业化工有限公司 | Corrosion-resistant alloy material and application thereof |
| CN106555155A (en) * | 2016-10-13 | 2017-04-05 | 国家电网公司 | It is a kind of to accelerate the stabilized pre-oxidization treatment method of Surface Rust of Weathering Steel |
| CN108034907A (en) * | 2017-11-24 | 2018-05-15 | 万鑫精工（湖南）有限公司 | A kind of gear reducer input shaft |
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