焊后热处理对耐候钢焊接接头裂纹扩展速率影响研究OA

To clarify the influence of post-weld heat treatment on the fatigue crack propagation characteristics of weathering steel welded joints and support the lightweight design and post-weld process optimization of rail vehicle welded structures,the MAG welded joints of Q460NE and S355J2W(H)weathering steels commonly used in rail vehicles were taken as re-search objects.The effects of two processes,i.e.,post-weld heat treatment plus shot peening and post-weld shot peening,on the crack propagation rate of the joints were studied through fatigue crack propagation tests.Based on the obtained fatigue crack propagation test data of Q460NE and S355J2W(H)welded joints,the da/dN-K curves of the joints under the two pro-cesses were fitted by using the Paris formula.The results show that:(1)With the increase of stress intensity factor,the fa-tigue crack propagation rates of the two types of steel welded joints under the two processes are generally similar without significant difference;(2)The m values of the da/dN-K curves of the four groups of welded joints fitted by the Paris formula are stably distributed in the range of 3.5±0.4.The m value of post-weld heat treatment plus shot peening is slightly lower than that of post-weld shot peening,and the difference in m values between Q460NE and S355J2W(H)joints is only 0.10-0.23,indicating that post-weld heat treatment has a limited effect on the crack propagation rate of Q460NE and S355J2W(H)welded joints.This study can provide a reference for the lightweight application of rail vehicles.