Improving low-temperature impact toughness of A516 Gr.70 steel plate after simulated post-weld heat treatment

To solve the problem of fluctuations in the impact toughness of A516 Gr.70 low-alloy steel plates with a thickness of 60 mm after welding and post-weld heat treatment, a thermal simulation experiment was conducted. The main reason for the fluctuations in hardness and impact properties of the steel plates in the as-rolled and welded states was found to be the presence of obvious coarse spherical pearlite organization in the near surface layer. By optimizing the temperature regime of the heat treatment furnace and adding a post-furnace air cooling device, the impact toughness of the low-alloy steel plates for low-temperature pressure vessels delivered in the normalized condition was significantly improved, with the pass rate increasing from 81.27% to 96.27%.