Optimization of welding process of heterogeneous high strength steel based on PLC control

Based on the investigation of the welding behavior of the heterogeneous high strength steel under the coupling of multi factors of welding parameters, PLC was used to control the laser welding process, the welding process of HC550/DP780 high strength steel was optimized by orthogonal experiment. The results showed that, the laser power is the most important influence on the weld width, the width and the tensile strength of the HC550/DP780 heterogeneous high strength steel, followed by welding speed and defocusing amount; The optimum welding parameters of HC550/DP780 unequal thickness and high strength steel are A2B2C2, which the laser power is 1200 W, the welding speed is 2000 mm/min, the defocusing amount is −0.5 mm; tensile strength and elongation of HC550/DP780 welding joint under optimized welding parameters are 998.6 MPa and 11.9%, the fracture location in the HC550 base metal heat affected zone, which shows ductile fracture characteristics. Keywords: HC550/DP780, PLC control, Laser welding, Welding proces