Application of post-weld treatment (PWHT) in improving properties of martensitic heat-resistant steel thick plate by cold metal transfer plus pulse (CMT plus P) welding

In this study, the welded joints of G115 steel of 35 mm thickness were fabricated using cold metal transfer plus pulse (CMT + P) welding. Then, the effect of post-weld treatment (PWHT) temperature on the microstructure and mechanical properties was studied and the strengthening and softening mechanism was analyzed. With the increase in PWHT temperature, more precipitates were released along grain boundaries and grains, and Cr segregation occurred in these regions to form ferrite, inducing the decrease in strength and hardness and the increase in plasticity and toughness. Then as the tempering temperature increased from 760 to 780 degrees C, the hardness and strength were reduced by 25% and 15%, respectively, while the impact toughnesses in WM and HAZ was improved by 1.4 times and 1.2 times, respectively.

Automated summary

This study investigates the effect of PWHT temperature on the microstructure and mechanical properties of welded joints of G115 steel. The results show that with the increase in PWHT temperature, more precipitates are released along grain boundaries and grains, leading to a decrease in strength and hardness and an increase in plasticity and toughness.