HOT-ROLLED WIRE ROD FOR HIGH STRENGTH STEEL WIRE AND PRODUCTION METHOD THEREFOR

• Main Authors: SAKAMOTO AKIRA, KODAMA JUNICHI, OFUJI YOSHIHIRO
• Format: Patent
• Language: English; Japanese
• Published: 26.10.2017
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; TREATMENT OF ALLOYS OR NON-FERROUS METALS

PROBLEM TO BE SOLVED: To provide a hot-rolled wire rod capable of providing high strength steel wire excellent in strength and durability without being subjected to patenting.SOLUTION: The hot-rolled wire rod for a high strength steel wire is provided that contains, by mass%, C:0.35 to 0.50%, Si:0.10 to 0.80%, Mn:0.60 to 0.90%, Cr:0.15% or less, Mn amount(%)+2×Cr amount(%)<0.9% and the balance Fe with inevitable impurities. The hot-rolled wire rod has a pearlite area ratio of 60% or more, a pro-eutectoid ferrite area ratio satisfying formula (1), the balance one or two kind of bainite and pseudo pearlite, strength TS (MPa) satisfying formulae (2) and (3), an average strength variation in one coil being within ±50 MPa and a diameter of 4.1 to 5.5.mm. Pro-eutectoid ferrite amount(%)≤50-55×C amount(%)+20×Si amount(%) formula... (1). 900×C amount(%)+50×Si amount(%)+300≤TS≤900×C amount(%)+50×Si amount(%)+400... formula (2). TS≤1200-80×D... formula (3). D:hot-rolled wire rod diameter (mm).SELECTED DRAWING: None 【課題】パテンティング無しで強度、延性に優れた高強度鋼線を得られる熱間圧延線材を提供する。【解決手段】質量％でＣ：０．３５〜０．５０％、Ｓｉ：０．１０〜０．８０％、Ｍｎ：０．６０〜０．９０％、Ｃｒ：０．１５％以下、Ｍｎ量(％)＋２×Ｃｒ量(％)＜０．９％、残部はＦｅと不可避不純物で、パーライト面積率６０％以上、初析フェライト面積率が式（１）を、残部がベイナイト及び疑似パーライトの１種又は２種、強度ＴＳ（ＭＰａ）が式（２）（３）を満足し、１コイル内の強度ばらつきが平均±５０ＭＰａ以内で直径４．１〜５．５ｍｍの高強度鋼線用熱間圧延線材。初析フェライト量(％)≦５０-５５×Ｃ量(％)＋２０×Ｓｉ量(％)...式（１）９００×Ｃ量（％）＋５０×Ｓｉ量(％)＋３００≦ＴＳ≦９００×Ｃ量（％）＋５０×Ｓｉ量(％)＋４００...式（２）ＴＳ≦１２００-８０×Ｄ...式（３） Ｄ：熱間圧延線材線径（ｍｍ）【選択図】なし