JP4789225B2

JP4789225B2 - Manufacturing method of high strength steel loom material

Info

Publication number: JP4789225B2
Application number: JP2001027827A
Authority: JP
Inventors: 建次郎伊東; 輝彦末次; 広森川; 隆山内
Original assignee: Nippon Steel Nisshin Co Ltd
Current assignee: Nippon Steel Nisshin Co Ltd
Priority date: 2001-02-05
Filing date: 2001-02-05
Publication date: 2011-10-12
Anticipated expiration: 2021-02-05
Also published as: JP2002235113A

Description

【０００１】
【産業上の利用分野】
本発明は、繊維との接触で磨耗し易いフラットヘルド、ドロッパー、筬羽、変形筬、リード等の織機部材であって、耐食性と靭性および耐繊維磨耗性に優れたに優れた高強度鋼製織機部材用素材の製造方法に関する。
【０００２】
【従来の技術】
フラットヘルド、ドロッパー、筬羽、変形筬、リード等の織機部材にはステンレス鋼ＳＵＳ４２０Ｊ２を焼入れした組織強化材が使用されている。この種の織機部材は、織物に使用される繊維の材質改善、生産能率を向上させるために高速度化等にともなって、磨耗環境が過酷になってきている。その結果、部品寿命が低下し、補修部品の煩雑な交換が余儀なくされている。また、使用環境によっては、織機部材が腐食し織りあがった織物が汚染される問題も発生している。
【０００３】
【発明が解決しようとする課題】
本発明は、そのような問題を解消すべく案出されたものであり、耐繊維磨耗については、硬質なＴｉ炭化物やＮｂ炭化物をマトリックスに分散させることにより耐摩耗性と、適正な焼入れ・焼戻し温度で造り込んだ高耐食性材により、長期にわたって使用される耐食性と靭性および耐繊維磨耗性に優れた高強度鋼製織機部材を提供することを目的とする。
【０００４】
【課題を解決するための手段】
本発明の耐食性と靭性および耐繊維磨耗性に優れた高強度鋼製織機部材用素材の製造方法は、その目的を達成するため、Ｃｒ：１０〜１８質量％、Ｃ：０．２１〜０．５質量％を含有し、さらにＴｉおよび／またはＮｂを、Ｔｉ：単独で０．０５〜１質量％、Ｎｂ：単独で０．０５〜１質量％或いはＴｉ＋Ｎｂ：合計量で０．０５〜１質量％を含み、残部Ｆｅ及び不可避的不純物の組成からなる鋼に、下記（１）、（２）式により求まるＴに対して、焼入れ温度がＴ±５０℃、焼戻し温度が１５０〜５００℃で熱処理を施し、鋼の組織をマルテンサイト相とするとともに、鋼のマトリックス中にＴｉおよび／またはＮｂの炭化物を０．１質量％以上分散析出させることを特徴とするものである。
ここで、Ｔ＝２８０×ｋ^*＋１２００ ‥‥‥（１）
ｋ^*＝ｌｏｇ｛Ｃ％−０．１６（Ｎｂ％＋Ｔｉ％）｝‥‥‥（２）
（２）式右辺の各項は合金元素の含有量（質量％）である。
【０００５】
【作用】
本発明者等は、磨耗損傷した織機部材や実際に使用した繊維等を多数取り寄せ、磨耗損傷部分や繊維をミクロ的な観点から調査した。その結果、磨耗した部材の大半では、細かい線状に研削されたような疵が磨耗部分に観察された。また、使用された繊維には、アルミナや炭化珪素等の硬質粒子の付着が検出された。研削されたような疵や硬質粒子の付着から、この時の磨耗現象は、硬質粒子が介在した磨耗であることが分かった。なお、本明細書では、繊維と織機部材の接触面に硬質粒子が介在し、振動または摺動過程で織機部材の接触面が硬質粒子等で擦過・研削される磨耗をアブレッシブな磨耗と言う。
アブレッシブな磨耗は、種々の磨耗現象の中で最も激しい磨耗であり、この磨耗に耐える材料の開発が望まれている。
【０００６】
これまでの鋼製織機部材は、鋼の組織強化、加工硬化等により得られる硬さと比較してアルミナ、炭化珪素等の硬質粒子が硬いために、アブレッシブな磨耗に対しては耐えられなかった。
そこで、本発明者等は、アルミナや炭化珪素と同等の硬さを有する炭化物に着目し、鋼のマトリックス中に硬質炭化物を分散析出させ、アブレッシブな磨耗に対する耐磨耗性の検討を行った。その結果、Ｔｉ炭化物またはＮｂ炭化物の単独または複合炭化物を分散析出させることで、アルミナや炭化珪素によるアブレッシブな磨耗を抑制する効果があることを見出し、耐磨耗性に優れた織機部材用耐磨耗鋼の開発を行った。
本発明者等は、さらに耐食性の改善、靭性の向上についても検討したところ、添加元素とその添加量、および焼入れ・焼戻し温度の関係において耐食性、靭性が向上することを見出した。
【０００７】
なお、ここで、本発明方法で得られる鋼材の特性評価に使用した各種の評価・測定方法について、説明しておく。
[炭化物析出量の測定]
炭化物の固溶・析出処理によって、炭化物量を制御した試料を沃化アルコール液に浸漬し、超音波を加えて鋼を溶解した後、液中に残った炭化物量の残渣量より求めた。炭化物の形態は残渣のＸ線解析で固定して求め、個々の金属元素量は湿式分析およびガス分析装置で求めた。
【０００８】
[耐食性の評価]
耐食性の評価は、ＪＩＳＺ２３７１による塩水噴霧試験を７２時間実施し、試験後の錆発生の有無で評価した。
[靭性の評価]
焼入れ・焼戻し後の靭性の評価は、ＪＩＳＺ２２４８の押し曲げ法により、密着または曲げ、曲げ部での破断の有無で評価した。
【０００９】
[耐摩耗性の評価]
試験は、フラッドヘルドのメール穴に、織物の化学繊維（ＴＦＤ７５／３６Ｆ外径約１２０μｍ）を通し、接触摺動させ接触部の磨耗深さを測定した。試験の条件は、繊維の張力：約５０ｇで、試験の回転速度：８０ｒｐｍ（摺動速度：０．１ｍ／ｓ）、試験時間：１０時間である。
試験片フラッドヘルドのメール部の耐摩耗性評価は、繊維と接触磨耗した部分の磨耗量を求め、ＳＵＳ４２０Ｊ２の磨耗深さを基準とし、下記（３）式に基づいて求めた耐磨耗指数Ｍ（％）で行った。耐磨耗指数Ｍが小さいほど耐磨耗性に優れていることを示す。
耐磨耗性指数Ｍ（％）＝Ｄｉ÷Ｄｏ×１００ ‥‥‥（３）
ここで、ＤｏはＳＵＳ４２０Ｊ２の磨耗深さ
Ｄｉは評価対象鋼の磨耗深さ
【００１０】
次に、本発明方法の内容を具体的に説明する。
本発明で対象とされる鋼材は、耐食性を付与するために１０〜１８質量％のＣｒを含んでいる。Ｃｒ含有量が８質量％を下回ると、Ｃｒ添加による防食効果が低減する。１０質量％以上にＣｒを添加するほど耐食性は向上するが、１８質量％を越えると熱間加工性が低下し、製造上問題となる。本発明材が用いられる腐食環境を考慮し、また材料の低コスト化を図ることからＣｒの上限は１８質量％とした。
【００１１】
Ｔｉおよび／またはＮｂは、炭化物の合計析出量が０．１質量％以上になるように、Ｔｉ：単独で０．０５〜１質量％、Ｎｂ：単独で０．０５〜１質量％またはＴｉ＋Ｎｂ：合計量で０．０５〜１質量％の割合で添加される。
炭化物合計析出量０．１質量％以上は、後述する実施例に記載しているように、耐磨耗性に及ぼす析出物の影響調査から見出された臨界値である。０．１質量％以上の合計析出量を確保することにより、炭化物のない鋼材に比較して格段に優れた耐磨耗性が得られる。
Ｔｉ：０．０５質量％以上、Ｎｂ：０．０５質量％以上またはＴｉ＋Ｎｂ：０．０５質量％以上に設定するとき、マトリックス中に分散析出した炭化物の合計析出量が０．１質量％以上になる。しかし、Ｔｉ、Ｎｂの成分は溶製時の湯流れ性の低下、金属間化合物生成による靭性の低下、素材コストの上昇等のため、Ｔｉ含有量の上限を１．０質量％、Ｎｂ含有量の上限を１質量％、Ｔｉ＋Ｎｂ合計含有量の上限を１質量％に設定した。
【００１２】
０．１質量％以上の炭化物を析出させるためには、Ｃを０．０５質量％以上含有させる必要がある。そして、Ｃは炭化物の生成に消費されるだけでなく、組織強化にも有効な成分であるが、０．５質量％を越える多量のＣの添加は共晶クロム炭化物の多量の析出を招き、材料品質の低下や熱間加工性等の低下を引き起こすため、Ｃ含有量の上限は０．５質量％とした。
本発明で対象とされる鋼材には、耐磨耗性向上のための硬質な炭化物形成元素のＺｒ、Ｖ、Ｗ等を、Ｔｉ、Ｎｂとの一部置換または複合添加として、Ｔｉおよび／またはＮｂと合量で総和が１質量％まで添加することができる。
【００１３】
さらに、本発明で対象とされる鋼材には、他の合金成分としてＮｉ、Ｍｏ、Ｃｕ等を含有させることもできる。例えば、焼入れ後のマルテンサイト相の確保やさらなる靭性等の改善のため０．１〜４質量％のＮｉ、耐食性改善のため０．１〜３質量％のＭｏ、耐食性、耐応力腐食割れ性等の改善のため０．２〜３質量％のＣｕの1種または２種以上を含有させても良い。
なお、製鋼過程での脱酸を目的とするＳｉ、Ｍｎの添加については、Ｓｉを０．０２〜２．５質量％、Ｍｎを０．０２〜３質量％の範囲で調整することが好ましい。
【００１４】
一方、織機部材用素材への多量のＣの添加や低温焼き入れ或いは高温焼戻し等の製法によっては、耐食性が損なわれることが確認され、その改善方法について検討した。これらの耐食性低下の原因を調査した結果、鋼中のＣｒがＣと結合してＣｒ₂₃Ｃ₆のクロム炭化物が析出していた。このクロム炭化物の析出によって耐食性向上に有効なＣｒが炭化物に取り込まれ、析出物近傍のＣｒが欠乏したため、耐食性が損なわれ腐食していることが分かった。また、焼入れ温度や焼戻し温度が不適切であれば耐食性のみならず靭性に大きな悪影響をもたらす。
【００１５】
本発明者等は、これらのことから、本発明鋼の耐食性および靭性を損なうことなく製造できる最善の製造方法について種々検討した。
種々の組成を有する鋼材について、焼入れ温度と耐食性および靭性の関係を検討した。種々の焼入れ温度で焼入れ熱処理した後、さらに４００℃の焼戻し処理を施した試料の耐食性と靭性を調査し、その結果を焼き入れ温度と未結合ｋ^*（ＴｉおよびＮｂと結合できなかったＣ量を表す指標）の関係で整理し、プロットしたものが図１である。
【００１６】
図１のマップ図で明らかなように、耐食性および靭性の両特性に優れる領域が認められた。この、耐食性および靭性の両特性に優れる中心線を回帰計算して求めた結果、回帰計算値：Ｔとして（１）式が得られた。
Ｔ＝２８０×ｋ^*＋１２００ ‥‥‥（１）
ここでｋ^*＝ｌｏｇ｛Ｃ％−０．１６（Ｎｂ％＋Ｔｉ％）｝‥‥‥（２）
【００１７】
さらに、(１)式の回帰直線より、±５０℃以上離れると、優れた耐食性や靭性が得られない。すなわち、回帰計算値：Ｔよりも、±５０℃以上離れると、低温側では耐食性が低下し、高温側では靭性が劣っている。
下限値を下回ると、Ｃｒ炭化物が固溶しきらず、未固溶のＣｒ炭化物が腐食の起点となって、耐食性を低下させる。一方、上限を上回ると、Ｃｒ炭化物が完全に固溶し耐食性が維持されるものの、オーステナイト粒が粗大化し、焼入れ後の靭性に悪影響を及ぼす。
以上の結果から、優れた耐食性および靭性を得るための適正な焼入れは、回帰計算値Ｔの±５０℃の温度範囲で行う必要がある。
【００１８】
また、回帰計算値Ｔの±５０℃の最適温度範囲で焼入れしても焼戻し温度によって、耐食性や靭性が低下する場合があることも分かった。
最適組成（Ｃ：０．３２質量％、Ｃｒ：１５．５６質量％、Ｎｂ：０．４５質量％）を有する鋼について、焼入れ温度を３水準（何れもＴの±５０℃の最適温度範囲内）変えて、焼戻し温度の耐食性および靭性に対する影響について調査した結果を、図２に示す。
【００１９】
１００℃以下の焼戻し温度では、曲げ試験で破断し、充分な靭性が得られておらず、１５０℃以上で、密着曲げで破断せず靭性の改善が認められた。１５０℃未満の焼戻しでは、高温からの焼入れ時に変態・生成したマルテンサイト相の歪みが十分に除去できず、織機部材で要求される靭性まで回復できない。しかし、５００℃を越えると、塩水噴霧試験で錆が発生し耐食性の低下が認められた。この結果から、最適な焼入れ温度範囲で処理しても、焼戻し温度によっては、耐食性および靭性が損なわれる領域が存在することが確認できる。
【００２０】
すなわち、本発明は、最適な焼入れ温度で熱処理し、さらに、１５０〜５００℃の範囲で焼戻し熱処理を施すことによって、優れた耐食性と靭性を得ることになる。
以上、本発明方法で優れた耐食性と靭性を得るための最適な製造条件は、焼入れ温度が回帰計算値Ｔの±５０℃で、焼戻し温度が１５０〜５００℃で熱処理を施すことになる。ここでＴは上記（１）式により求まる。
【００２１】
【実施例】
以下に、実施例について説明する。
表１に比較鋼および発明鋼の主要成分を示す。材料は溶製後溶体化処理して板厚５ｍｍまでに熱間圧延し、さらに７８０℃で９時間加熱後炉冷し、酸洗、冷間圧延、焼鈍を繰り返し、板厚０．３ｍｍに仕上げ、試験用素材とした。繊維によるアブレッシブな磨耗に対する耐摩耗性の評価用の試験片は、比較鋼および発明鋼の板厚０．３ｍｍの素材を、温度が回帰計算値Ｔの上下の各温度からの焼入れ処理と、５０〜６００℃各温度での焼戻し処理の所定の焼入れ・焼戻しの熱処理を施し、織機部材のフラッドヘルドに加工して試験片とした。
【００２２】

【００２３】
前記した方法により、炭化物の析出量を測定し、耐食性、靭性、および耐摩耗性を評価した。
まず表２に、本発明鋼および比較鋼のＴｉ炭化物、Ｎｂ炭化物の析出量と耐摩耗性指標Ｍ（％）の評価結果を示す。比較鋼種６、７のようにＴｉおよびＮｂの添加量が少ないとＴｉ炭化物やＮｂ炭化物の析出も少なく、耐摩耗性指標Ｍが大きくなって耐摩耗性は得られなくなる。Ｔｉ炭化物やＮｂ炭化物の総析出量が多くなると、耐摩耗性指標Ｍが小さくなって、優れた耐摩耗性を示している。
このＴｉ炭化物とＮｂ炭化物の合計析出量と耐磨耗性指標Ｍの関係をグラフ化すると図３のようになる。炭化物の合計析出量が増加すると耐磨耗性指標Ｍは急激に小さくなり、炭化物の合計析出量０．１質量％を境に耐磨耗性指標Ｍは５０％未満に、すなわち、従来品と比較して２倍以上の寿命を持つフラッドヘルドが得られるので、前記したように本発明方法における炭化物の合計析出量を０．１質量％以上と規定したのである。
【００２４】

【００２５】
次に焼入れ温度・焼戻し温度と耐食性、靭性の関係について評価した。
その結果を、表３に示す。所定の合金組成を有し、本発明で規定する（１）式を満たす温度で焼入れ、１５０〜５００℃の範囲で焼戻しを行ったものは、耐摩耗性を有することは勿論、耐食性および靭性にも優れていた。これに対し、焼入れ温度が規定値よりも高い比較例では、靭性の点で満足できるものは得られなかった。また、焼入れ温度が低い比較例では、耐食性の点で満足できるものが得られなかった。さらに、焼戻し温度が高い比較例では耐食性の点で、焼戻し温度が低い比較例では靭性の点で満足できるものが得られなかった。
なお、鋼種６、７は、前記したように硬質炭化物を形成するＴｉ、Ｎｂ含有量が少ないために、Ｔｉ炭化物、Ｎｂ炭化物の析出も少なく、耐磨耗性の点で所期の目的を達成できていない。
【００２６】

【００２７】
【発明の効果】
以上に説明したように、本発明方法によれば、Ｔｉおよび／またはＮｂを含有させて硬質の炭化物を所定量以上析出させることにより、繊維によるアブレッシブな磨耗に対して優れた耐摩耗性を持たせるとともに、焼入れおよび焼戻しの処理を最適な温度で行うことにより、耐食性と靭性を向上させることができる。
これにより、織物の繊維による磨耗が問題になっている織機類の部材、特に、フラットヘルド、ドロッパー、筬羽、変形筬、リード等、アブレッシブな磨耗に対する耐摩耗性が要求される部位での磨耗対策が可能になるとともに、織機機械を始めこの種の関連機器そのものの寿命延長に多大な貢献が期待できる。
【図面の簡単な説明】
【図１】焼入れ温度と耐食性および靭性の関係を示す図。
【図２】焼戻し温度と耐食性および靭性の関係を示す図。
【図３】Ｔｉ炭化物およびＮｂ炭化物の合計析出量と耐摩耗性の関係を示す図。[0001]
[Industrial application fields]
The present invention is a loom member such as flat heald, dropper, wing feather, deformed ridge, lead, etc., which is easily worn by contact with fibers, and is made of high strength steel excellent in corrosion resistance, toughness and fiber abrasion resistance. The present invention relates to a method for manufacturing a material for a loom member.
[0002]
[Prior art]
A tissue reinforcing material obtained by quenching stainless steel SUS420J2 is used for loom members such as flat healds, droppers, wings, deformed wrinkles, and reeds. In this type of loom member, the wear environment has become severe with the increase in speed and the like in order to improve the material quality of fibers used in the woven fabric and improve the production efficiency. As a result, the service life of the parts is reduced, and complicated replacement of repair parts is unavoidable. Further, depending on the use environment, there is a problem that the loom members are corroded and the woven fabric is contaminated.
[0003]
[Problems to be solved by the invention]
The present invention has been devised to solve such a problem. Regarding fiber wear resistance, hard Ti carbide and Nb carbide are dispersed in a matrix to provide wear resistance and proper quenching and tempering. An object of the present invention is to provide a high strength steel loom member that is excellent in corrosion resistance, toughness, and fiber abrasion resistance, which is used over a long period of time, using a high corrosion resistance material built in at a temperature.
[0004]
[Means for Solving the Problems]
In order to achieve the object, the method for producing a material for a high-strength steel loom member having excellent corrosion resistance, toughness, and fiber abrasion resistance according to the present invention has Cr: 10 to 18% by mass, and C: 0.21 to 0.00. 5% by mass, and further Ti and / or Nb, Ti: 0.05 to 1% by mass alone, Nb: 0.05 to 1% by mass alone or Ti + Nb: 0.05 to 1% by total amount %, With the balance of Fe and the inevitable impurities composition, heat treatment at a quenching temperature of T ± 50 ° C. and a tempering temperature of 150 to 500 ° C. with respect to T obtained by the following formulas (1) and (2) The steel structure is made into a martensite phase, and Ti and / or Nb carbides are dispersed and precipitated in the steel matrix in an amount of 0.1% by mass or more.
Here, T = 280 × k ^* + 1200 (1)
k ^* = log {C% −0.16 (Nb% + Ti%)} (2)
(2) Each term on the right side of the equation is the content (mass%) of the alloy element.
[0005]
[Action]
The present inventors gathered a large number of worn-out loom members and actually used fibers, and investigated the wear-damaged parts and fibers from a microscopic viewpoint. As a result, in most of the worn members, wrinkles that were ground into fine lines were observed in the worn portions. Moreover, adhesion of hard particles such as alumina and silicon carbide was detected on the used fibers. From the adhesion of wrinkles and hard particles that were ground, the wear phenomenon at this time was found to be wear mediated by hard particles. In the present specification, wear in which hard particles are present on the contact surface between the fiber and the loom member and the contact surface of the loom member is abraded and ground by the hard particles in the vibration or sliding process is referred to as abrasive wear.
Abrasive wear is the most intense wear among various wear phenomena, and the development of materials that can withstand this wear is desired.
[0006]
Conventional steel loom members cannot withstand abrasive wear because hard particles such as alumina and silicon carbide are harder than the hardness obtained by strengthening the structure of steel, work hardening, and the like.
Accordingly, the present inventors have focused on carbides having the same hardness as alumina and silicon carbide, and have dispersed hard precipitates in a steel matrix to examine wear resistance against abrasive wear. As a result, it has been found that by dispersing and precipitating Ti carbide or Nb carbide alone or composite carbide, it has the effect of suppressing the abrasive wear caused by alumina and silicon carbide, and has excellent wear resistance for loom parts. We developed wear steel.
The inventors of the present invention have further investigated the improvement of corrosion resistance and the improvement of toughness, and found that the corrosion resistance and toughness are improved in relation to the additive element, its addition amount, and the quenching / tempering temperature.
[0007]
Here, various evaluation / measurement methods used for property evaluation of the steel material obtained by the method of the present invention will be described.
[Measurement of carbide precipitation]
A sample in which the amount of carbide was controlled by solid solution / precipitation treatment of carbide was immersed in an iodide alcohol solution, and the steel was dissolved by applying ultrasonic waves, and then the amount of carbide remaining in the solution was determined. The form of the carbide was determined by fixing by X-ray analysis of the residue, and the amount of each metal element was determined by a wet analysis and a gas analyzer.
[0008]
[Evaluation of corrosion resistance]
Corrosion resistance was evaluated by performing a salt spray test according to JISZ2371 for 72 hours, and evaluating whether or not rust was generated after the test.
[Evaluation of toughness]
The toughness after quenching and tempering was evaluated based on the presence or absence of adhesion or bending and fracture at the bent portion by the press bending method of JISZ2248.
[0009]
[Evaluation of wear resistance]
In the test, a fabric chemical fiber (TFD75 / 36F outer diameter of about 120 μm) was passed through the mail hole of the floodheld, and the contact depth was measured by sliding the contact portion. The test conditions were fiber tension: about 50 g, test rotation speed: 80 rpm (sliding speed: 0.1 m / s), and test time: 10 hours.
The wear resistance evaluation of the mail part of the test piece flood-held was obtained by calculating the wear amount of the part that was in contact with the fiber and based on the following equation (3) based on the wear depth of SUS420J2. (%). The smaller the wear resistance index M, the better the wear resistance.
Abrasion resistance index M (%) = Di ÷ Do × 100 (3)
Here, Do is the wear depth Di of SUS420J2, and the wear depth of the steel to be evaluated.
Next, the contents of the method of the present invention will be specifically described.
The steel material targeted by the present invention contains 10 to 18% by mass of Cr in order to impart corrosion resistance. When the Cr content is less than 8% by mass, the anticorrosion effect due to the addition of Cr is reduced. The corrosion resistance improves as Cr is added to 10% by mass or more, but if it exceeds 18% by mass, the hot workability is lowered, which causes a problem in production. Considering the corrosive environment in which the material of the present invention is used and reducing the cost of the material, the upper limit of Cr is set to 18% by mass.
[0011]
Ti and / or Nb are Ti: 0.05 to 1% by mass alone, Nb: 0.05 to 1% by mass alone, or Ti + Nb: so that the total precipitation amount of carbide is 0.1% by mass or more. The total amount is added in a proportion of 0.05 to 1% by mass.
The total carbide precipitation amount of 0.1% by mass or more is a critical value found from the investigation of the influence of precipitates on the wear resistance, as described in Examples described later. By ensuring the total precipitation amount of 0.1% by mass or more, the abrasion resistance that is remarkably superior to that of the steel material without carbide is obtained.
When Ti: 0.05% by mass or more, Nb: 0.05% by mass or more, or Ti + Nb: 0.05% by mass or more is set, the total amount of carbides dispersed and precipitated in the matrix is 0.1% by mass or more. Become. However, the components of Ti and Nb are 1.0% by mass for the upper limit of Ti content and Nb content due to a decrease in molten metal flow during melting, a decrease in toughness due to the formation of intermetallic compounds, an increase in material cost, etc. Was set to 1% by mass, and the upper limit of the Ti + Nb total content was set to 1% by mass.
[0012]
In order to precipitate 0.1% by mass or more of carbide, it is necessary to contain 0.05% by mass or more of C. C is not only consumed in the formation of carbides, but is also an effective component for strengthening the structure. However, the addition of a large amount of C exceeding 0.5% by mass causes a large amount of eutectic chromium carbide to precipitate, In order to cause deterioration of material quality and hot workability, the upper limit of the C content is set to 0.5% by mass.
In the steel materials targeted by the present invention, Zr, V, W, etc., which are hard carbide forming elements for improving wear resistance, are replaced with Ti, Nb, Ti, and / or The total amount of Nb and the total amount can be added up to 1% by mass.
[0013]
Furthermore, the steel material targeted by the present invention may contain Ni, Mo, Cu, etc. as other alloy components. For example, 0.1-4 mass% Ni for securing martensite phase after quenching and further improving toughness, 0.1-3 mass% Mo for improving corrosion resistance, corrosion resistance, stress corrosion cracking resistance, etc. In order to improve this, one or more of 0.2 to 3% by mass of Cu may be contained.
In addition, about addition of Si and Mn for the purpose of deoxidation in a steelmaking process, it is preferable to adjust Si in the range of 0.02-2.5 mass% and Mn in the range of 0.02-3 mass%.
[0014]
On the other hand, depending on the production method such as addition of a large amount of C to the material for the loom member, low temperature quenching or high temperature tempering, it was confirmed that the corrosion resistance was impaired, and an improvement method was examined. As a result of investigating the cause of the decrease in corrosion resistance, Cr in the steel was combined with C, and chromium carbide of Cr ₂₃ C ₆ was precipitated. It was found that the chromium carbide, which is effective for improving the corrosion resistance, was taken into the carbide by the precipitation of the chromium carbide, and the Cr in the vicinity of the precipitate was deficient. In addition, if the quenching temperature and tempering temperature are inappropriate, not only the corrosion resistance but also the toughness is greatly affected.
[0015]
Based on these facts, the present inventors have made various studies on the best manufacturing method that can be manufactured without impairing the corrosion resistance and toughness of the steel of the present invention.
For steel materials having various compositions, the relationship between the quenching temperature, corrosion resistance and toughness was examined. After the quenching heat treatment at various quenching temperatures, the corrosion resistance and toughness of the sample further tempered at 400 ° C. were investigated, and the results were calculated based on the quenching temperature and unbonded k ^* (the amount of C that could not be bonded to Ti and Nb) FIG. 1 shows the result of arrangement and plotting by the relationship of the index indicating).
[0016]
As is clear from the map in FIG. 1, a region excellent in both corrosion resistance and toughness was observed. As a result of the regression calculation of the center line that is excellent in both the corrosion resistance and toughness characteristics, Equation (1) was obtained as the regression calculation value: T.
T = 280 × k ^* + 1200 (1)
Here, k ^* = log {C% −0.16 (Nb% + Ti%)} (2)
[0017]
Furthermore, if the distance from the regression line of the equation (1) is ± 50 ° C. or more, excellent corrosion resistance and toughness cannot be obtained. That is, when it is more than ± 50 ° C. from the regression calculation value: T, the corrosion resistance is lowered on the low temperature side, and the toughness is inferior on the high temperature side.
If the lower limit is not reached, the Cr carbides are not completely dissolved, and the undissolved Cr carbides become the starting point of corrosion, thereby reducing the corrosion resistance. On the other hand, if the upper limit is exceeded, Cr carbides are completely dissolved and corrosion resistance is maintained, but austenite grains become coarse and adversely affect the toughness after quenching.
From the above results, proper quenching for obtaining excellent corrosion resistance and toughness needs to be performed within a temperature range of ± 50 ° C. of the regression calculation value T.
[0018]
It was also found that the corrosion resistance and toughness may be lowered depending on the tempering temperature even if quenching is performed within the optimum temperature range of ± 50 ° C. of the regression calculation value T.
About the steel which has the optimal composition (C: 0.32 mass%, Cr: 15.56 mass%, Nb: 0.45 mass%), the quenching temperature is 3 levels (all within the optimal temperature range of ± 50 ° C of T) FIG. 2 shows the results of investigation on the influence of tempering temperature on corrosion resistance and toughness.
[0019]
At a tempering temperature of 100 ° C. or lower, fracture occurred in a bending test and sufficient toughness was not obtained, and at 150 ° C. or higher, fracture was not caused by contact bending and improvement in toughness was observed. When tempering is less than 150 ° C., the distortion of the martensite phase that has been transformed / generated during quenching from a high temperature cannot be sufficiently removed, and the toughness required for the loom members cannot be recovered. However, when the temperature exceeded 500 ° C., rust was generated in the salt spray test, and a decrease in corrosion resistance was observed. From this result, it can be confirmed that there is a region where the corrosion resistance and toughness are impaired depending on the tempering temperature even if the treatment is performed within the optimum quenching temperature range.
[0020]
That is, according to the present invention, excellent corrosion resistance and toughness are obtained by performing heat treatment at an optimum quenching temperature and further performing tempering heat treatment in the range of 150 to 500 ° C.
As described above, the optimum production conditions for obtaining excellent corrosion resistance and toughness by the method of the present invention are heat treatment at a quenching temperature of ± 50 ° C. of the regression calculation value T and a tempering temperature of 150 to 500 ° C. Here, T is obtained by the above equation (1).
[0021]
【Example】
Examples will be described below.
Table 1 shows the main components of comparative steel and invention steel. The material is melted and hot-rolled to a thickness of 5 mm, heated at 780 ° C. for 9 hours, cooled in the furnace, repeatedly pickled, cold-rolled and annealed, and finished to a thickness of 0.3 mm. The test material was used. A test piece for evaluation of abrasion resistance against abrasive wear caused by fibers was obtained by quenching a material having a thickness of 0.3 mm of comparative steel and invention steel from each temperature above and below the regression calculation value T, and 50 Predetermined quenching and tempering heat treatment at each temperature of ˜600 ° C. was performed and processed into a flood heald of a loom member to obtain a test piece.
[0022]

[0023]
By the above-mentioned method, the precipitation amount of carbide was measured, and corrosion resistance, toughness, and wear resistance were evaluated.
First, Table 2 shows the amount of precipitation of Ti carbides and Nb carbides of the present invention steel and comparative steel and the evaluation results of the wear resistance index M (%). When the addition amount of Ti and Nb is small as in comparative steel types 6 and 7, the precipitation of Ti carbide and Nb carbide is also small, the wear resistance index M becomes large, and the wear resistance cannot be obtained. When the total precipitation amount of Ti carbide or Nb carbide increases, the wear resistance index M decreases, indicating excellent wear resistance.
A graph of the relationship between the total precipitation amount of Ti carbide and Nb carbide and the wear resistance index M is shown in FIG. As the total precipitation amount of carbide increases, the wear resistance index M decreases rapidly, and the wear resistance index M decreases to less than 50% at the boundary of the total precipitation amount of carbide of 0.1% by mass. Since a flood heald having a life that is twice or longer than that of the present invention is obtained, the total amount of carbide precipitation in the method of the present invention is defined as 0.1% by mass or more as described above.
[0024]

[0025]
Next, the relationship between quenching and tempering temperatures and corrosion resistance and toughness was evaluated.
The results are shown in Table 3. Those having a predetermined alloy composition, quenched at a temperature satisfying the formula (1) defined in the present invention, and tempered in the range of 150 to 500 ° C. have not only wear resistance but also corrosion resistance and toughness. Was also excellent. On the other hand, in the comparative example in which the quenching temperature is higher than the specified value, no satisfactory product was obtained in terms of toughness. Moreover, in the comparative example with low quenching temperature, what was satisfactory in terms of corrosion resistance was not obtained. Furthermore, the comparative example having a high tempering temperature was not satisfactory in terms of corrosion resistance, and the comparative example having a low tempering temperature was not satisfactory in terms of toughness.
Steel types 6 and 7 achieve the intended purpose in terms of wear resistance due to the low Ti and Nb content that forms hard carbides as described above, so that the precipitation of Ti and Nb carbides is small. Not done.
[0026]

[0027]
【The invention's effect】
As described above, according to the method of the present invention, Ti and / or Nb is contained and a hard carbide is precipitated in a predetermined amount or more, so that it has excellent wear resistance against abrasive wear caused by fibers. In addition, the corrosion resistance and toughness can be improved by performing the quenching and tempering treatment at an optimum temperature.
As a result, weaving parts of looms where abrasion due to fabric fibers is a problem, especially wear in areas where wear resistance to abrasive wear is required, such as flat healds, droppers, wings, deformed wrinkles, leads, etc. In addition to being able to take measures, it can be expected to make a significant contribution to extending the life of this type of related equipment, including loom machines.
[Brief description of the drawings]
FIG. 1 is a graph showing the relationship between quenching temperature, corrosion resistance and toughness.
FIG. 2 is a graph showing the relationship between tempering temperature, corrosion resistance and toughness.
FIG. 3 is a graph showing the relationship between the total precipitation amount of Ti carbide and Nb carbide and the wear resistance.

Claims

Cr: 10 to 18% by mass, C: 0.21 to 0.5% by mass, and Ti and / or Nb, Ti: 0.05 to 1% by mass, Nb: 0.05 alone ˜1% by mass or Ti + Nb: Steel containing 0.05 to 1% by mass in total and having the balance of Fe and unavoidable impurities is quenched with respect to T obtained by the following formulas (1) and (2) Heat treatment is performed at a temperature of T ± 50 ° C. and a tempering temperature of 150 to 500 ° C. to make the steel structure a martensite phase, and at least 0.1% by mass of Ti and / or Nb carbide is dispersed in the steel matrix. A method for producing a material for a high-strength steel loom member having excellent corrosion resistance, toughness, and fiber abrasion resistance, characterized by being deposited.
Here, T = 280 × k ^* + 1200 (1)
k ^* = log {C% −0.16 (Nb% + Ti%)} (2)
(2) Each term on the right side of the equation is the content (mass%) of the alloy element.