2011 年 29 巻 3 号 p. 58s-61s
In this study, hot-wire laser welding was used to develop the welding method for the lap joint of 980MPa class high-strength steel sheets (thickness: 1 mm) with a wide gap. Detailed phenomena of wire melting and bead formation during welding were understood using the high-speed camera, and then the optimum welding condition and the mechanical properties of weld joints were investigated. The fiber laser with hot wire was used for welding the lap joint with the gap of 1 mm. The welding parameters such as the laser output of 3kW, spot diameter of 1.5mmφ, welding speed of 1.5m/min and the wire feeding speed of 3.8 m/min were fixed. The welding parameters of hot wire such as wire insertion angle, wire insertion position, and current of wire were varied. Moreover, shear test of the weld joints were done. As a result, upper and lower sheets with gap of 1 mm were well joined without weld defects in the welding parameters such as the wire insertion positions (from the laser spot center) of 3mm and the wire insertion angle of 70° and the wire currents of 102∼116A. Moreover, the tensile shear strengths of weld joints were 500∼600MPa regardless of the wire current.
