Mechanical properties and microstructure of TIG+MIG welded joint of T91 steel

The mechanical properties, creep strength and high temperature ageing of TIG+MIG welded joint of T91 steel were tested. Microstructure and fracture morphology of the joint was analyzed. The creep strength of 625℃ for 17958 h is 70 MPa, which can deduce that the sustained strength after 10⁵ h is 46.5 MPa and the FATT is -13℃. It is proved that the properties of TIG+MIG welding joint at high temperature is determined by the change of microstructure. Furthermore, M₂₃C₆ plays an important role.