Investigation on laser welding of a novel hot-stamped steel with 2000 MPa

Abstract

This present work is the first investigation on the laser welding of the novel hot-stamped steel with 2000MPa (HSS2000). Softening was present in mixed-grain HAZ and tempered zone, due to martensite transformation, precipitated carbons and partial recovery of martensite lath. Tensile strength of welded joint was ∼1500 MPa, 80% of base metal, due to the presence of soften zone. However, the softening cannot be eliminated with decreasing laser heat input but it did not influence the tensile strength of welded joints. Thus, the laser welding of HSS2000 is acceptable in the heat input range of 67∼86 J/mm because the tensile strength can reach 1500 MPa, which is superior to other ultra-high strength steels at present. HSS2000 has a potential application in the automotive manufactures in the future.

Keywords

• Hot-stamped steel
• Laser welding
• Softening
• Tensile strengtrh
• Martensite