焊接残余应力下氢扩散的数值模拟

Numerical simulation of hydrogen diffusion under welding residual stress

利用有限元软件ABAQUS,开发了一个焊接残余应力作用下氢扩散的耦合有限元计算程序,对湿硫化氢环境下16MnR钢液化石油气球罐焊接接头焊态残余应力诱导氢扩散的分布规律进行数值模拟,并与无应力状态下的氢扩散进行了比较,为掌握焊接接头氢致开裂的判据打下基础。结果表明,在焊接残余应力作用下,氢向高应力区富集,经过一段时间后,达到稳定。在热影响区附近,形成一个氢浓度低谷,两侧分别形成浓度梯度界面和应力梯度界面,能够诱导氢向高应力区长程扩散。

Using finite element analysis code ABAQUS,a sequential coupling calculating program on hydrogen diffusion has been developed.Using this program,the effect of as-welded residual stress on the hydrogen diffusion was numerically simulated for the welded joint of a liquefied petroleum gas spherical tank made of 16MnR steel.The hydrogen diffusion without the effect of welding residual stress was also taken into account and compared.This method provides a reference for mastering the criterion of hydrogen induced cracking of welded joint.The result shows that under the welding residual stress field,the hydrogen diffuses and accumulates toward the higher stress zone,attaining stability through a period of time.There is a low hydrogen concentration value around the heat affected zone,where the residual stress gradient and concentration gradient are formed,which can cause the hydrogen long-range diffusion to the high stress zone.