SCM435冷镦钢奥氏体连续冷却转变曲线研究

Study on Continuous Cooling Transformation Curves of Austenite in SCM435 Cold Heading Steel

利用Gleeble-3800热模拟试验机,采用热膨账法结合硬度测量,研究了SCM435冷镦钢的连续冷却转变过程,通过光学显微镜、电子探针分析了不同冷速下SCM435冷镦钢的组织转变行为.结果表明,SCM435冷镦钢冷速低于1℃/s时,组织主要为铁素体＋珠光体＋贝氏体,在1-10℃/s冷速范围内,组织主要为贝氏体和少量珠光体＋铁素体或马氏体,冷速大于10T/s时,组织为马氏体.

The continuous cooling transformation curves of the austenite in SCM435 cold heading steel was studied by the thermal dilation method and hardness test on the Gleeble-3800 thermal simulated test machine. The transformation behaviors of the microstructures in SCM435 cold heading steel at various cooling speed was analyzed by optical microscopy analysis and electron probe. The study results show that the microstructures in the SCM435 cold heading steel are composed of ferrite, pearlite and bainite when the cooling speed is below 1℃/s, while the micro structures are composed of main bainite, small pearlite and ferrite or martensite when the cooling speed is in the range from 1 ℃ /s to 10 ℃ /s and the microstructures is the simplex martensite when the cooling speed is over 10 ℃/s.