Abstract
Hydrogen related delayed fracture is a critical issue to be solved to enhance the application of high-strength steels. This hold true with the high strength steels and its welds used in automotive applications. The trend of the increase of the strength of steels used will continue, therefore, it is important to investigate the hydrogen related fracture of high-strength automotive steels. In this study, hydrogen diffusion and accumulation behavior in the high-strength steel welds has been investigated by numerical simulation. The residual stress distribution of the resistance spot welds was considered as the driving force of hydrogen diffusion. The hydrogen diffusion was simulated under residual stress field with different initial hydrogen distributions and boundary conditions. When the diffusible hydrogen distributed uniformly in the weld metal just after welding, hydrogen diffused rapidly after welding and retained slightly at the center of the weld metal. When the diffusible hydrogen was introduced through the surface of the welded joint, diffusible hydrogen accumulated in the area of high tensile stress. In addition, the rate of increase of the hydrogen concentration was dependent on the distance from the surface of the welded joint.
