Q310/Q345电阻点焊接头组织与疲劳性能研究

Study on microstructure and fatigue performance of Q310/Q345 resistance spot welding joint

通过金相组织分析、硬度试验、脉动拉伸疲劳试验及疲劳断口形貌分析,研究1.5mm Q310+3mm Q345电阻点焊接头的组织和疲劳性能。结果表明:Q310钢和Q345钢组织较为相似,母材组织均为先共析铁素体+珠光体,热影响区为少量铁素体+珠光体,熔核区为板条马氏体和少量贝氏体。硬度值分布从熔核到母材呈阶梯式下降趋势,熔核区是硬度值最高的区域。疲劳断口位于熔核区,类型为微孔型+解理型混合断裂,应力集中是疲劳断裂的主要原因。

Through the analysis of the microstructure, hardness test,pulsating tensile fatigue test and the analysis of fatigue fracture morphology,this paper studied the microstructure and fatigue performance of resistance spot welding joint of 1.5 mm Q310 and 3 mm Q345. The results show that,the microstructure of Q310 and Q345 are similar,the base organization is pro-eutectoid ferrite and pearlite,the microstructure of HAZ is a few ferrite and pearlite. The microstructure of nugget area is lath martensite and bainite. From the nugget area to the base material,the hardness value distribution is in a step downward trend,the hardness value of nugget is the highest of the whole joint. The fatigue fracture is located in the nugget area. And the type of fatigue fracture is mixed with micropore and cleavage,the main cause of fatigue fracture is stress concentration.