Very high cycle fatigue behavior of bridge steel welded joint  

作　　者：Chao He Yongjie Liu Donghui Fang Qingyuan Wang 

机构地区：[1]Department of Mechanics and Engineering Science,Sichuan University,Chengdu 610065,China [2]Department of Civil Engineering&Architecture,College of Jincheng,Sichuan University,Chengdu 610065,China

出　　处：《Theoretical & Applied Mechanics Letters》2012年第3期36-40,共5页力学快报（英文版）

基　　金：supported by the China National Funds for Distinguished Young Scientists(10925211);the National Natural Science Foundation of China(50878174)

摘　　要：Very high cycle fatigue（VHCF） behaviors of bridge steel（Q345） welded joints were investigated using an ultrasonic fatigue test system at room temperature with a stress ratio R = -1. The results show that the fatigue strength of welded joints is dropped by an average of 60% comparing to the base metal and the fatigue failure still occurred beyond 10~7 cycles.The fatigue fracture of welded joints in the low cycle regime generally occurred at the solder while at the heat-affected zone（HAZ） in the very high cycle regime.The fatigue fracture surface was analyzed with scanning electron microscopy（SEM）,showing welding defects such as pore,micro-crack and inclusion were the main factors on decreasing the fatigue properties of welded joints.The effect of welding defects on the fatigue behaviors of welded joints was discussed in terms of experimental results and finite element simulations.Very high cycle fatigue（VHCF） behaviors of bridge steel（Q345） welded joints were investigated using an ultrasonic fatigue test system at room temperature with a stress ratio R = -1. The results show that the fatigue strength of welded joints is dropped by an average of 60% comparing to the base metal and the fatigue failure still occurred beyond 10~7 cycles.The fatigue fracture of welded joints in the low cycle regime generally occurred at the solder while at the heat-affected zone（HAZ） in the very high cycle regime.The fatigue fracture surface was analyzed with scanning electron microscopy（SEM）,showing welding defects such as pore,micro-crack and inclusion were the main factors on decreasing the fatigue properties of welded joints.The effect of welding defects on the fatigue behaviors of welded joints was discussed in terms of experimental results and finite element simulations.

关 键 词：welded joint S-N curve failure mechanism very high cycle fatigue 

分 类 号：TG407[金属学及工艺—焊接] TG146.15[一般工业技术—材料科学与工程]