焊接热输入对超低碳贝氏体钢热影响区CGHAZ组织性能影响

为探索不同焊接热输入对超低碳贝氏体钢焊接接头热影响区(CGHAZ)粗晶区显微组织和冲击性能的影响,采用Gleeble 3500热模拟试验机模拟不同热输入,研究热输入对Q420q EN钢接头热影响区粗晶区的显微组织和冲击韧性的影响,并采用扫描电镜、示波冲击和透射电镜等技术对钢热影响区粗晶区进行了表征。结果表明,随着焊接热输入的变化,热影响区粗晶区的显微组织变化明显,板条贝氏体和粒状贝氏体的含量发生相应变化;同时,随着焊接热输入由18 kJ/cm增加到30 kJ/cm,接头热影响区粗晶区在-20℃下的冲击韧性先增加后减小。

Effect of welding heat input on microstructure and properties of CGHAZ of ultra-low carbon bainitic steel

In order to explore the effect of different welding inputs on the microstructure and impact properties of coarse grain heat-affected zone(CGHAZ)of ultra-low carbon bainitic steel welded joint,Gleeble-3500 thermal simulation machine was used to simulate different inputs to study the effects of different heat inputs on the microstructure and impact toughness of CGHAZ of Q420qEN steel joint.And the CGHAZ was characterized.The results show that as the welding heat input increases,the microstructure of CGHAZ becomes coarser,the lath bainite decreases and granular bainite increases;meanwhile,when the welding heat input increases from 18kJ/cm to 30 kJ/cm,the impact toughness of CGHAZ at-20℃ increases first and then decreases.