Evolution of microstructural and mechanical properties of fiber laser welded dual phase steels

Abstract

Over the past decade, Dual Phase steels are extensively used in the automotive industry to reduce the weight of the vehicles. The Fiber laser welding has been showing superior weld quality over other laser welding methods. DP 600 grade is most widely used grade among DP steels. Influence of heat input on microstructural and mechanical properties for the given thickness has been investigated. Widths of weld zone and Heat Affected Zone have decreased with decreasing the heat input. Rapid cooling rates in the fusion zone have resulted in martensitic structure and hardness also increased in proportional. Tensile test and notch tensile test of the welded joints have been confirmed that weld joints are stronger than that the base material. From the ensile test along the weld joint of all heat inputs, it has been observed that lower heat input weld joints have shown better properties over the others.