Characteristics of Butt Welding on Al–Si Coated Boron Steel and Hot-Stamped Steel Using Disk Laser

The hot-stamping process has continuously been studied in an effort to reduce the weight of the finished products by increasing the strength and reducing the thickness as part of the effort to achieve better fuel efficiency and reduce environmental pollution in the transport industry. In this study, a specimen was welded with a disk laser before and after the hot-stamping process of 1.2 mm Al–Si-coated boron steel. After butt welding was performed with a disk laser at a maximum power of 4 kW as a heat source, the characteristics of the weld and the base metal were compared through hardness measurements and the microstructures were observed. There was a difference in the critical speed in that full penetration could be obtained at the time of butt welding due to the difference in the structures of the two different materials. For the hot-stamped steel, there was a sharp reduction of the hardness in the heat-affected zone. It was found that the hardness was reduced due to the intermetallic compound which formed after the Al–Si coating layer on the surface of the specimen flowed into the weld zone during the welding process.