Microstructural and mechanical characterization of laser-welded 22MnB5 hot stamping steel

ABSTRACT

Advanced high-strength steels (AHSS) have evolved over the past decades, establishing themselves as widely used materials in the automotive industry. Among the AHSS, the 22MnB5 steel stands out, which, through hot stamping, is shaped into complex geometries, achieving high mechanical strength values. The result is a steel with a microstructure formed by martensite and traces of bainite, providing high energy absorption capacity, ideal for applications requiring high strength and durability. This study presents the mechanical and microstructural characterization of hot-stamped and laser-welded 22MnB5 steel, compared to the base material. Welding led to an increase in tensile strength, especially in the yield strength, which showed an increase of approximately 10%, while the ultimate tensile strength increased by about 3%. The hardness of the fusion zone and the base material varied around 500 HV, while the heat-affected zone exhibited softening, reaching approximately 350 HV. Despite localized changes in the microstructure and a reduction of about 50% in total elongation, the feasibility of welding 22MnB5 steel with fiber laser and two opposite passes was demonstrated.

Keywords
Advanced high-strength steel; Hot stamping; 22MnB5; Laser welding