摘要
采用激光-MAG复合焊进行了Q890/Q550异种钢焊接试验,研究不同焊接热输入对异种钢焊接接头显微组织和力学性能的影响。试验结果表明,在相同热输入下,焊缝两侧过热区主要由板条马氏体和少量贝氏体组织组成,细晶区为致密的板条马氏体组织,Q890钢侧的马氏体含量比Q550侧多,板条更加粗短,焊缝冲击断口具有剪切韧窝特征,冲击韧性优于热影响区;随着热输入从3.5 kJ/cm增加到9.6 kJ/cm,过热区晶粒粗化,贝氏体逐渐增多,马氏体含量减少,焊缝和热影响区冲击吸收能量略微减小。三种热输入下拉伸试件均断在母材Q550钢,断后伸长率相当,断裂方式为韧性断裂,焊接接头强度高于母材。
The laser-MAG hybrid welding of Q890/Q550 dissimilar steel joints was studied,and the effects of different welding heat input on microstructures and mechanical properties of dissimilar steel joints were tested and analyzed. Results show that at the same heat input,the overheated zones on both sides of the weld mainly consist of martensite and a small amount of bainite. Dense martensite is observed in the fine grained region. The martensite in the Q890 steel side is more than that in the Q550 steel side,the weld fracture has the characteristics of shear dimples and the impact toughness of the weld is higher than that of the heat affected zone. As the heat input increases from 3.5kJ/cm to 9.6kJ/cm,the amount of bainite gradually increases with the grain coarsening,and the impact energy of weld zone and heat affected zone slightly decrease. All The tensile specimens of three kinds of heat input are fractured in the Q550 steel,the fracture mode is ductile fracture,and the joint strength is higher than that of the base metal.
出处
《焊接》
2018年第5期5-11,共7页
Welding & Joining
