Q690桥梁钢粗晶热影响区的强韧化研究

Study on Strengthening and Toughening of Coarse-Grained Heat-Affected Zone of Q690 Bridge Steel

研究了Q690桥梁钢的焊接性能,对热模拟粗晶热影响区进行了分析,为Q690桥梁钢的推广和运用提供基础数据。根据Gleeble-3500获取了不一样焊接热输入(15~50 kJ/cm)下Q690桥梁钢热仿真模拟粗晶热影响区,并对其进行组织和性能分析,研究结果表明:焊接热仿真模拟粗晶热影响区显微组织主要为板条贝氏体、粒状贝氏体和少量马氏体,随着焊接热输入的增加,显微组织中马氏体的含量降低,粒状贝氏体的含量增大;当焊接热输入为30 kJ/cm时,获得的组织主要是板条贝氏体,其大角度晶界密度最高,冲击吸收功最高。

In order to provide basic information for the promotion and application of Q690 bridge steel,the weldability and the simulated coarse-grained heat-affected zones(CGHAZ)of Q690 bridge steel were investigated.Using Gleeble-3500 to simulate the CGHAZ of Q690 bridge steel under different welding heat inputs(15~50 kJ/cm),and its microstructure and properties were analyzed.The results indicate that under different welding heat inputs conditions,the microstructure of CGHAZ obtained by simulation is mainly composed of lath bainite(LB),granular bainite(GB)and slight of martensite.As the increase of heat inputs(HIs),the martensite content in the microstructure decreases,the content of granular bainite increases.When the HIs is 30 kJ/cm,the obtained microstructure of simulated CGHAZ is mainly LB,with the highest density of large-angle grain boundaries,resulting the highest impact absorbed energy.