GH4169合金与S31042钢线性摩擦焊接头组织及力学性能

S31042 steel is a typical 25Cr-20Ni type austenitic heat-resistant steel with excellent resistance to oxidation and creep rupture strength near 600^oC. This austenitic steel is widely used as a super-heater or re-heater in ultra-super critical plants with steam specifications as high as 600^oC and 25 MPa. To reduce CO₂ emissions and improve power generation, the application of advanced ultra-super critical plants (steam parameters 700^oC and 30 MPa) can be promoted. Owing to its excellent mechanical properties as well as good corrosion resistance at elevated temperature above 650^oC, GH4169 alloys have the potential to be used in advanced ultra-super critical plants. Practically, it is meaningful to investigate the welding process of GH4169/S31042 dissimilar materials. In this work, the joint between dissimilar materials (S31042/GH4169) was studied by linear friction welding, and the microstructures and mechanical properties of the joint were investigated by OM, SEM, TEM, hardness testing, tensile testing, and creep testing at 700^oC. Good metallurgic bonding was obtained under the optimized welding process parameters of 25 Hz (frequency), 2 mm (amplitude), 100 MPa of frictional pressure, and 150 MPa of forging pressure. Dynamic recrystallization occurred and the secondary phase particles precipitated within the weld zone. The microhardness of the welded joint was higher than that of the base metal, and the tensile properties of the joint were higher than S31042 steel, which is attributed to both fine grain and dispersion strengthening.