SCM435低合金中碳冷镦钢Φ12 mm盘条混晶成因分析与工艺改进  

Analysis on Cause of Mixed Grain Size of SCM435 Low Alloy Medium Carbon Cold Heading SteelΦ12 mm Wire Rod and Process Improvement

作　　者：董庆 阮士朋 李敏锐 Dong Qing;Ruan Shipeng;Li Minrui(Technology Center,Xingtai Iron and Steel Corp Ltd,Xingtai 054027;Hebei Province Engineering and Technology Innovation Center for Wire Rod,Xingtai 054027;Department of Quality Control,Xingtai Iron and Steel Corp Ltd,Xingtai 054027)

机构地区：[1]邢台钢铁有限责任公司技术中心,邢台054027 [2]河北省线材工程技术创新中心,邢台054027 [3]邢台钢铁有限责任公司质控部,邢台054027

出　　处：《特殊钢》2022年第2期48-50,共3页Special Steel

基　　金：河北省省级科技计划项目(205676134H)资助。

摘　　要：协议要求SCM435钢热轧盘条奥氏体晶粒度≥7级以及断面收缩率≥35%。试验结果表明,原始工艺条件下,Φ12 mm SCM435钢盘条混晶组织沿着线材的表层分布,从表面到深度0.5mm区域为混晶区,奥氏体晶粒度为4级(25%)+7.5级(75%);其余心部区域晶粒度7.5级。显微组织中马氏体(M)比例高,断面收缩率低。通过混晶组织产生原因的分析,采取将精轧温度由935℃降至850℃、吐丝温度由900℃降至850℃等措施,使Φ12 mm SCM435钢热轧盘条晶粒度由7.5级升至8.5级,盘条表层混晶组织消失;同时降低了显微组织中M比例,断面收缩率均值由35%提升到40%。According to specification of SCM435 steel hot rolled wire rod,the austenite grain size is≥7 grade and the reduction of area is≥35%.The test results show that in the original process the mixed grain size structure ofΦ12 mm SCM435 steel wire is distributed along the surface of the wire rod with depth 0.5 mm,and the austenite grain size rating is 4(25%)+7.5(75%);the rating of austenite grain size at the rest of the core area is 7.5.There is more martensite in the microstructure,and the reduction of area of steel is lower.Through analysis on the causes of mixed grain structure,and decreasing finishing rolling temperature from 935℃to 850℃,and outgoing temperature decreasing from 900℃to 850℃the rating of austenite grain size ofΦ12 mm SCM435 steel hot rolled wire rod increases from 7.5 to 8.5 and the mixed grain structure on surface of wire rod disappeared,the proportion of martensite in the microstructure decreases,and the average reduction of area increases from 35%to 40%.

关 键 词：SCM435钢 混晶 断面收缩率 工艺改进 进精轧温度 

分 类 号：TG335.11[金属学及工艺—金属压力加工]