Evaluation of the Microstructure and Microhardness of Laser Welded Low-Alloy Chromium-Molybdenum Steel

In this study, the microstructure and hardness of ۱.۷۲۱۹ steel in the welding process using a continuous fiber laser were investigated. The effect of laser power and welding speed on the geometric characteristics, microstructure, and hardness of the fusion zone and heat affected zone (HAZ) was evaluated. Studies have shown that with increasing laser power, the depth of weld penetration increases, and due to the heat concentration and high cooling rate in laser welding, martensitic microstructures were observed in the weld zone and in the HAZ. The presence of this type of microstructure clearly showed its effect on hardness changes. The hardness of the base metal was in the range of ۱۹۰±۱۰ HV. The hardness values for the heat-affected zone and the fusion zone increased with the laser power used for welding and were in the range of (۴۵۰-۶۵۶) ±۱۰ HV. Comparison of the hardness values in the samples showed that increasing the laser power increased the heat input and hardness of the microstructure in the fusion zone and HAZ and increased the possibility of defects formation and propagation in weld zone.

کلیدواژه ها:

Laser Welding ، Fiber Laser ، Microstructure ، Microhardness ، ۱.۷۲۱۹ steel