Effect of welding thermal cycle and cold working on the ductility of SN490 steel under low and high-speed loading

Welding thermal cycle and cold working are two harmful factors to ductility. In this paper, the effect of welding thermal cycle and cold working on the ductility of SN490 steel was discussed through low, medium and high-speed tensile tests, and their mechanisms of affecting ductility were revealed by microvoid model. It was found that the deterioration of ductility of SN490 by welding heat input is caused by the precipitation of a great deal of carbides, and the effect of cold working only relates to the void grow and void coalescence in SN490. Ductility decrements of SN490 steel by welding thermal cycle and cold working were also compared to each other, and the results show that welding thermal cycle is more harmful to the ductility of SN490 than cold working.