Interface evolution and mechanical properties of 17-4 PH/316L dissimilar stainless steel by laser forming repairing

Laser forming repairing technology has been widely used in the industrial field. However, there are limited studies on the interface evolution in dissimilar materials by laser repair technology. This study uses laser solid forming technology to deposit 17-4 PH martensitic stainless steel onto a 316L austenitic stainless steel substrate. The heat-affected zone (HAZ) and the compositionally diluted region were analyzed as key repair interface areas. The effects of laser power on phase components and elemental macro-segregation in the interface region were investigated, and interfacial bond strength was evaluated through a shear experiment. The experimental results reveal that rapid solidification and substrate dilution lead to the formation of distinct interface regions: the unmixed zone (UMZ), visible streak zone (VSZ), and composition mixed zone (CMZ), with epitaxial grain growth at the interface. As laser power increases, shear stress initially rises before declining. This behavior is attributed to melt pool convection, at optimal laser power, which enhances dilution and improves interfacial bonding. These findings provide valuable insights into the laser repair of dissimilar stainless steels, offering guidance for optimizing repair parameters to enhance interface performance.