A review on the laser welding of coated 22MnB5 press-hardened steel and its impact on the production of tailor-welded blanks

The current demand for vehicles with high fuel efficiency, improved safety and enhanced crashworthiness qualities is being met by making use of high strength components with tailored mechanical properties which are made using tailor-welded blanks. During their production, the surface of the blank needs to be protected against oxidation and decarburisation. Protective coatings are used to protect the steel surface, with Aluminium-Silicon or Zinc-based coatings being the most popular. This work provides a review on the state-of-the-art as well as the issues associated with the laser welding of coated 22MnB5 grade steel to be used in the production of tailor-welded blanks. The paper provides a summary of existing solutions available to overcome these issues while discussing their limitations and the potential for future work. List of Abbreviations and Symbols: AHSS: Advanced-high Strength Steel; UHSS: Ultra-high Strength Steel; UTS: Ultimate Tensile Strength; PHS: Press-hardened Steel; HS: Hot Stamping; AR: As received; LWB: Laser-welded Blank; TWB: Tailor-welded Blank; ARW: As-received Welded; ARWHS: As-received Welded then Hot-Stamped; HSW: Hot-Stamped then Welded; BM: Base Material; HSBM: Hot-Stamped Base Material; BOP: Bead-on-Plate; CR: Cooling Rate; DIC: Digital Image Correlation; DP: Dual Phase; EPMA: Electron Probe Micro-Analyzer; EDX: Energy Dispersive X-Ray Spectroscopy; FLW: Fibre Laser Welding; FZ: Fusion Zone; GI: Galvanised; GA: Galvannealed; HAZ: Heat-affected Zone; LBW: Laser Beam Welding; LME: Liquid Metal Embrittlement; PAG: Prior Austenite Grains; BIW: Body-in-white