不同冷速下Q1100高强钢焊接热影响区粗晶区的组织转变特征
２０１７年１月第４１卷第１期 Vol．４１No．１Jan．２０１７
DOI :１０．１１９７３/j x g ccl２０１７０１０２２
收稿日期:２０１５-１１-２２;修订日期:２０１６-１１-０８作者简介:方俊飞(１９７７－),男,安徽黄山人,副教授,博士.不同冷速下Q １１００高强钢焊接热影响区粗晶区的
组织转变特征
方俊飞,徐震霖,斯松华,相小草
(安徽工业大学材料科学与工程学院,马鞍山２４３０００)
摘 要:利用Gleeble-３５００型热模拟试验机对Q１１００高强钢的焊接过程进行模拟,
采用热膨胀法结合显微组织与硬度测试,绘制了该钢的模拟热影响区连续冷却转变曲线(SHCCT 曲线)
,研究了不同冷却速率下焊接热影响区粗晶区的组织转变特征和硬度变化规律.结果表明:在模拟焊接
条件下,该钢的奥氏体化温度明显高于平衡状态下的奥氏体化温度;当冷却速率低于２??s －１时,
热影响区粗晶区为全贝氏体组织;当冷却速率为２~１２??s －１时,热影响区粗晶区为贝氏体和马氏
体的混合组织;当冷却速率超过１２??s －１时,热影响区粗晶区得到全马氏体组织;随着冷却速率增
加,焊接热影响区粗晶区的硬度逐渐增大.
关键词:高强钢;热影响区粗晶区;组织转变;SHCCT 曲线
中图分类号:TG４０６ 文献标志码:A 文章编号:１０００-３７３８(２０１７)０１-０１０７-０４Microstructure Transformation Characteristic of CGHAZ of Q １１００Hi g h-Stren g th Steel at Different Coolin g Rates
FANG Jun-fei ,XU Zhen-lin ,SI Son g -hua ,XIANG Xiao-cao
(School of Materials Science and En g ineerin g ,Anhui Universit y of Technolo gy ,Maanshan ２４３０００,China )Abstract :The weldin g p rocess of Q１１００hi g h-stren g th steel was simulated with Gleeble-３５００thermal simulator ,and then SHCCT (simulated HAZ continuous coolin g transformation )dia g ram of the steel was obtained b y usin g thermal ex p ansion measurement combined with microstructure anal y sis and hardness testin g ．The
microstructure transformation characteristics and hardness chan g e rule of coarse-g rained heat-affected zone (CGHAZ )were studied at different coolin g rates．The results show that ,the austenitizin g tem p erature of the steel in simulated weldin g condition was si g nificantl y hi g her than that in the e q uilibrium state．The CGHAZ was full bainite when the coolin g rate was under ２??s －１,a mixed microstructure of bainite and martensite was obtained
when the coolin g rate was ２－１２??s －１,and the CGHAZ was full martensite when the coolin g rate was over
１２??s －１．The hardness of CGHAZ increased g raduall y with the increase of coolin g rate．Ke y words :hi g h-stren g th steel ;coarse g rain heat-affected zone ;microstructure transformation ;SHCCT
(simulated HAZ continuous coolin g transformation )dia g ram ０ 引 言
随着现代工程机械及冶金矿山机械的快速发
展,为提高机械设备的使用性能,要求所用钢材具有
较高的屈服强度和良好的冲击性能[１－２].但随着钢材强度的增加,焊接难度增大,强韧性匹配不易控制,熔合区及热影响区性能恶化,降低了机械设备的使用性能[３－５].Q１１００高强钢能满足工程结构向大型化二轻量化和高效能化方向发展的要求,在工程起重机和混凝土泵车等机械设备上具有良好的应用前景.但该钢的强度高,焊接难度大,焊接热影响区性能难以控制.为有效控制Q１１００高强钢在焊接时
热影响区出现的性能恶化,作者利用Gleeble-３５００型热模拟试验机对该钢的焊接过程进行了模拟,绘
制了该钢的模拟热影响区连续冷却转变曲线
(SHCCT 曲线)
,研究了不同冷却速率下焊接热影７０１万方数据