Laser Welded Blanks applications for Al – Si coated Hot Stamped parts (HS – LWB) are significantly increasing in modern car designs. Mass savings are reached thanks to the higher strength level of the hot-stamped materials and parts integration with the reduction of thickness and joining overlap.
Two different steels are coated with an Al – Si protective layer. This very thin layer protects them from corrosion and improves the paint adhesion. They are joined by laser welding, without locally removing the Al – Si coating prior welding. During this process, aluminum contained in the coating layer may mix into the weld pool.
In this study, multi scale microstructural charac-terization of the weld seam using SEM – EDX analysis were performed to analyze deeply the metallurgical transformations during hot stamping. The EDX method is used to investigate the local chemical composition and weld mixing, especially the effect of aluminum content on phases ratio. Combining nano indentation of those phases, the hardness of each phase can be measured and those phases can be identified.
Additionally, mechanical properties of the weld are investigated drawing a micro hardness profile in the weld seam. Charpy testing is also used to determine energy absorption, with the V – notch in the weld.