Study of Microstructure and Mechanical Properties of Dissimilar Friction Welded Martensitic Stainless Steel 410 to Austenitic Stainless Steel 304

With regard to the industry demand for welding dissimilar metals, which are not possible to be welded by conventional welding, friction welding process can be a proper approach. In this study, friction welding of two stainless steels, martensitic 410 to austenitic 304, with variable parameters of friction time (40, 50, and 40 s), friction force (90, 100, and 120 kN), and forging force (130, 150, and 180 kN), under the constant rotating speed (850 RPM) and forge time (60 s), was investigated. Microscopic characterization using optical and scanning electron microscopes, and elemental analysis using energy dispersive X-ray spectroscopy were carried out on the welds. Soundness of the weld joints was evaluated using tensile and microhardness tests. Fracture surfaces of the tensile specimens were examined as well. The structure of the welded samples composed of acicular and rough martensite and elongated grains adjacent to 410 and 304 stainless steels, respectively. Tempering heat treatment locally caused converting rough martensite to lath martensite. The results showed that the tensile strength of the samples was in the range of 400-520 MPa, and the fractography revealed the occurrence of a brittle fracture. Microhardness measurement revealed that the highest hardness value was obtained in 410 stainless steel, at the heat-affected zone close to the interface. An appropriate friction weld joint with a tensile strength of 751 MPa was obtained after heat treatment of the weld location, and with the aid of selecting optimal parameters of 50 s friction time, 120 kN friction force, 180 kN forging force.