Study on temperature field simulation and mechanical properties of laser welded DP980 steel joints

Abstract:

High strength steel DP980 was welded using fiber laser, and the temperature field was evaluated via numerical simulation. The results reveal that the peak temperature of weld center reached 3204 ℃ and then cooled rapidly。The fusion zone contained mainly martensitic microstructure with hardness 30% higher than that of the base metal. The ultimate tensile strength of the fusion zone reached 1115.7 MPa, while the elongation was 49.1% of the base metal. The stress-strain curve of the softened zone exhibited obvious yield platform, and the ultimate tensile strength (850.7 MPa) was lower than the base metal (986.9 MPa) significantly. The ultimate tensile strength of the welded joint reached 87.1% of base metal, while the elongation reached 32.7%. All the tensile and Erichsen test samples failed at the softened zone. The major strain of the base metal was higher than the welded joint.