Pulsed Laser Weldability of the Third Generation Advanced High Strength Steel

Abstract

In order to meet the demands of vehicular safety and greenhouse gas emission reduction, the automotive industry is increasingly using Advanced High Strength Steels (AHSS) in the production of the components. With the development of the new generation of AHSS, it is essential to study their behavior to manufacturing processes used in the automotive industry. For this purpose, the welding capability of newly developed third-generation Gen3 980T steel was investigated using the Nd:YAG laser welding with different parameters conditions. The analysis was made by uniaxial tensile tests, micro-hardness Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). The criteria used to evaluate the quality of the weld were the distance between the fracture and the weld bead and the surface finish. It was observed a relationship between the quality of the weld and the energy density, expressed by a partial penetration for values below the optimal, and by irregularities in the weld bead and a high number of spatters for the values above the optimal. During welding, the phase transformation occurs, leading to a high amount of martensite. This fact leads to an increase of 53.7% of hardness in the fusion zone. Further analyses need to be done in order to quantify the amount of each phase, but this is a topic for future research.