Performance Evaluation and Application of the Laser Welded Joint with Filler Wire for Al-Si Coated Press-Hardened Steels

Abstract

Laser welding of Al-Si coated press-hardened steel (PHS) is considered as a challenge in its practical application due to the possible formation of bulk blocky ferrite in the weld metal (WM). In the present study, the relationship between the mechanical properties and the microstructure was investigated. The tensile test results showed that the tensile strength for the specimens ruptured in the gauge length were all over 1450 MPa accompanied with the elongation over 4%. Based on the fatigue tests, the fatigue strength by up-and-down method was around 9.2 × 10 3 N. The Charpy impact tests showed that the average obtained impact energy were all around 19 J for the welded joints at room temperature and decreased temperature as low as −40 °C. In particular, no obvious ferrite could be traced in the WM. In addition, the negligible microhardness fluctuation was considered as the main factor devoting to the superior comprehensive properties of the laser welded joint of Al-Si coated PHS. In this case, the automotive safety component of door ring with satisfied quality has been successfully fabricated.