Recent advances in mitigating fusion zone softening during laser welding of Al-Si coated 22MnB5 press-hardened steels

Abstract

The automotive industry is seeking reduced vehicle weight and improved safety of newer generation vehicles to meet global zero-emission targets. Tailor-welded blanks offer a solution to meet this demand by producing lightweight yet strong components, such as the B-pillar, using laser-welded press-hardened steels. The laser welding of Al-Si coated PHSs causes the coating to be diluted into the melt pool which can cause premature failure due to the presence of a softer ferrite phase in an otherwise martensitic joint. Currently, laser ablation is used to remove the Al-Si layer prior to welding, but other techniques have been proposed which can potentially bypass the need to remove the coating and instead, welding directly through the coating. This study examines the problem of fusion zone softening during the laser welding of Al-Si coated 22MnB5 and discusses recently proposed novel solutions that can solve the issue without the prior removal of the Al-Si coating before welding or using expensive filler materials during welding. The paper concludes with several viable recommendations for future work that can be used as potential directions for further research.

Keywords

• automotive industry
• tailor-welded blanks (TWBs)
• laser welding
• press-hardened steels (PHSs)
• Al-Si coated 22MnB5
• surface-modification techniques