焊接残余应力对氢扩散影响的有限元模拟

利用ABAQUS有限元软件开发的氢扩散耦合计算程序，对焊态和焊后热处理状态下残余应力对氢扩散的影响进行了数值模拟，并与无应力状态下的氢扩散进行了比较．结果表明，存在焊接残余应力梯度时，氢向高应力区富集，在热影响区附近，有一个氢浓度低谷，这是氢向高应力区长程扩散所致．经过焊后热处理，应力松弛效果明显，残余应力大幅下降，对氢扩散的影响也大大降低，氢的最高浓度降低了近40％．因此，焊后热处理可以有效降低材料在氢环境下开裂的敏感性．

Finite Element Simulation of the Effect of Welding Residual Stress on Hydrogen Diffusion

A sequential coupling calculation method on hydrogen diffusion has been developed based on the finite element program-ABAQUS. Using this method, the effect of welding residual stress on the hydrogen diffusion was numerically simulated for the as-weld condition and postweld heat treatment (PWHT) condition. The diffusion without the effect of stress was also taken into account and compared with those with stress. The results show that hydrogen will diffuse and accumulate in the higher stress region under the existence of welding residual stress gradient. A low hydrogen concentration valley exists near the heat affected zone(HAZ), which is caused by the long-range diffusion of hydrogen to the high stress zone. After the PWHT, stress relaxation is obvious and the residual stress is greatly decreased, which influences the hydrogen diffusion and makes the hydrogen concentration decrease about 40%. Therefore, PWHT can effectively improve the susceptibility of material to environment hydrogen cracking.