Fibre laser welding of dual phase steels

Abstract

The fibre laser welding of two different dual phase steels HCT980X and HCT600X was evaluated. The sheets with thickness of 1.2 mm were welded using the solid-state fibre laser IPG type YLR 4500 with maximum output 4.5 kW and wave length 1060 nm at graduated beam powers and welding speeds. The microstructure of welded samples was analysed, microhardness and tensile strength were measured. The heat input influenced the microstructure of the fusion zone and heat affected zone. The microhardness increased in the fusion zone and even more in the heat affected zone of HCT980X steel, which was the consequence of martensite and bainite formation in these areas. The tensile strength of joints achieved the strength of the HCT600X steel and all joints fractured in the HCT600X base metal.