Investigation on microstructure and properties of dissimilar joint between TRIP800 and QP980 fabricated by laser welding

Abstract

Dissimilar weld joints of QP980 and TRIP800 were fabricated by a fibre laser. The microstructure and mechanical properties of dissimilar weld joints were studied. The tensile properties of weld joints were not influenced by the narrow softening zone with a less reduction in hardness of ∼25 HV from the QP980, which contributed to fracture in TRIP800. The DIC images showed that the location of maximum strain was changed from the QP980 side to TRIP800 side during the tensile test of QP980 (1.2 mm)–TRIP800 (1.4 mm) joints. The dissimilar weld joints were characterised by the limited dome height test (LDH). The LDH values were varied with the punch pole location, as a result of the softening zone and non-uniform microstructure on the heat-affected zone of joints.