热处理对P355NL1钢不同焊接工艺接头残余应力及力学性能的影响

Effect of Heat Treatment on Residual Stress and Mechanical Properties of P355NL1 Steel Joint with Different Welding Processes

利用X射线测试系统和拉伸试验机对轨道车辆用P355NL1钢手工MAG多道焊与机械手自动MAG多道焊对接接头热处理前后的残余应力及拉伸性能进行了测试,研究了去应力退火热处理对不同焊接接头残余应力分布和拉伸性能的影响。结果表明:热处理前后手工MAG焊与机械手MAG焊焊接接头纵向与横向的残余应力分布趋势一致,均沿焊缝中心线近似对称,焊缝及近缝热影响区存在高的残余拉应力且随距焊缝距离的增加,残余应力值降低,直至母材变为压应力;热处理可以显著降低焊缝及近缝区周围的残余应力峰值,但对P355NL1钢焊接接头拉伸性能的影响很小。

The residual stress and tensile properties of the butt joints of P355NL1 steel for rail vehicles prepared by manual MAG multi-pass welding and robot automatic MAG multi-pass welding before and after heat treatment were tested by X-ray testing system and tensile testing machine. And the effect of stress relief annealing heat treatment on the residual stress distribution and tensile properties of different welded joints was studied. The results show that the longitudinal and transverse residual stress distribution trends of the manual MAG welding and robotic MAG automatic welding joints before and after heat treatment are consistent. They are both approximately symmetrical along the centerline of the weld. There is high residual tensile stress in the weld and heat-affected zone near the weld, and with the increase of the distance from the weld, the residual stress decreases until that the stress in the base material becomes compressive stress. Heat treatment can significantly reduce the peak residual stress around the weld and the area near the weld, while has little effect on the tensile properties of P355NL1steel welded joints.