Effect of Welding Heat Circulation on the Microstructure and Mechanical Properties of 500MPa Ultra fine Grained Steel in HAZ

摘要

Focusing on the need of actual production, physical analogue experiments were done on the 400MPa ultra fine grained steel under different welding heat circulations. The experiment results showed that grains growing up and performance dropping was inevitable, the coarsening temperature range was 1000～1200°C; where the heating temperature was 800°C in the Heat Affected Zone, the soften was the most obvious, but when the cooling rate t_(8/5)<10s, the soften disappeared; speeding up the cooling rate could improve the microstructure of the Heat-affected Zone effectively and made the mechanical properties of the joint better than that of the base metal.