Research on Microstructure and Mechanical Properties of Laser Welding of BR1500HS Joints

Abstract

In this research, BR1500HS high strength steel was laser welded under various process parameters. The welded samples were heated in a furnace for 5 min with a temperature of 900 °C and then water-quenched. The effects of process parameters and quenching process on mechanical properties and microstructure of the joints were investigated. The results show that when the heat input is 1440 J/cm, the best mechanical properties of the welded joint can be obtained. When the welding speed increases, the minimum hardness increases, and the width of the softened area decreases; while the laser power increases, the width of the softened area increases, and the minimum hardness does not change significantly. As the welding speed increases, the front-bead width A, back-bead width B, and the height of smooth segment H all decrease; while the laser power increases, the back-bead width B increases, the front-bead width A and the height of the smooth segment H increase first and then decrease. The front-bead width A reaches the maximum when the laser power is 3000 W and the height of the smooth segment H does not change much.