Microstructure evolution and mechanical properties of linear friction welded S31042 heat-resistant steel

S31042 heat-resistant steel was joined by linear friction welding (LFW) in this study. The microstructure and the mechanical properties of the LFWed joint were investigated by optical microscopy, scanning electronic microscopy, transmission electron microscopy, hardness test and tensile test. A defect-free joint was achieved by using LFW under reasonable welding parameters. The dynamic recrystallization of austenitic grains and the dispersed precipitation of NbCrN particles resulting from the high stress and high temperature in welding, would lead to a improvement of mechanical property of the welded joint. With increasing the distance from the weld zone to the parent metal, the austenitic grain size gradually increases from ∼1 μm to ∼150 μm, and the microhardness decreases from 301 HV to 225 HV. The tensile strength (about 731 MPa) of the welded joint is comparable to that of the S31042 in the solution-treated state.