Abstract: According to the more strict requirements of PWHT put forward by the design institute and the manufacturer, the influence of the limit PWHT condition on the mechanical properties was studied with 136 mm thickness SA387Gr11CL2 steel plate. The results show that the tensile properties of the steel with full thickness (1.6 mm under the surface, 1/4 of plate thickness and 1/2 of plate thickness) at room temperature are still acceptable. However, at 0 ℃ and below, the corresponding impact absorbed energy decreases gradually with the decrease of impact temperature. The -20 ℃ impact absorbed energy at 1/2 of the plate thickness has reached the lower limit of the standard requirements, and the surplus is not enough. The microstructure analysis combined with metallography and SEM shows that the carbide in the microstructure will segregate and grow along the grain boundary due to excessive rigor PWHT, resulting in obviously worse toughness of the steel plate.

Key words: SA387Gr11CL2 steel plate, post-welding heat treatment (PWHT), simulation, mechanical properties