SCM435冷镦钢连续冷却过程中的组织转变及球化退火  

Structural Transformation during Continuous Cooling and Spheroidizing for SCM435 Cold Heading Steel

作　　者：于学森 李战卫 王金涛 张宇 陈金军 YU Xuesen;LI Zhanwei;WANG Jintao;ZHANG Yu;CHEN Jinjun(Institute of Research of Iron and Steel,Shasteel,Zhangjiagang Jiangsu 215625,China;Bar and Wire Rod Plant,Jiangsu Shagang Group Co.,Ltd.,Zhangjiagang Jiangsu 215625,China)

机构地区：[1]江苏省(沙钢)钢铁研究院,江苏张家港215625 [2]江苏沙钢钢铁有限公司棒线厂,江苏张家港215625

出　　处：《上海金属》2024年第5期55-59,共5页Shanghai Metals

摘　　要：利用Gleeble-3800热模拟试验机测定了SCM435冷镦钢的热膨胀曲线。通过金相分析和硬度试验获得了钢的动态连续冷却转变曲线。研究了原始显微组织对钢球化退火效果的影响。结果表明:以小于0.5℃/s的速率冷却后,SCM435钢的组织主要为铁素体和珠光体,以1℃/s及以上速率冷却后组织为贝氏体和马氏体以及少量铁素体,以3℃/s及以上速率冷却后组织为马氏体和贝氏体,以15℃/s及以上速率冷却后组织全部为马氏体。采用相同工艺球化退火时,马氏体和贝氏体的球化效果优于珠光体和铁素体。通过优化轧制工艺试制的原组织为贝氏体和马氏体的SCM435钢盘条球化退火后,组织中碳化物分布均匀,球化效果好,球化退火时间明显缩短。Thermal expansion curves of SCM435 cold heading steel was measured by Gleeble-3800 thermal simulation testing machine.The dynamic continuous cooling transformation curves of the steel was obtained via both metallographic examination and hardness test.The influence of the prior microstructure on spheroidizing effect of the steel was studied.The results showed that the microstructure of SCM435 steel consisted predominantly of ferrite and pearlite after cooling at rate less than 0.5℃/s,of bainite and martensite,and a small amount of ferrite after cooling at rate of 1℃/s or above,of bainite and martensite after cooling at rate of 3℃/s or above,and all was martensite after cooling at rate of 15℃/s or above.In being spheroidized by the same process,the martensite and bainite was superior to the pearlite and ferrite in spheroidizing effect.The SCM435 steel wire rod with prior structures such as bainite and martensite,trial-produced by an optimized rolling process,exhibited microstructure containing uniformly distributed carbides and good spheroidizing effect after spheroidizing,and its spheroidizing time was significantly shortened.

关 键 词：SCM435冷镦钢 动态CCT曲线 贝氏体 马氏体 球化退火 

分 类 号：TG142.1[一般工业技术—材料科学与工程]