Microstructure and Mechanical Properties of the Friction Welded Joint between X53CrMnNiN219 and X45CrSi93 Stainless Steel

Dissimilar metals friction welding of austenitic–martensitic stainless steels is commonly used for manufacturing engine valves in automobile industry. In this study, X53CrMnNiN219 (austenitic stainless steel) and X45CrSi93 (martensitic stainless steel) valve steel rods were welded by friction welding. The welded joint was then heat treated at 760 ◦C for 60 min. Mechanical properties of the welded and heat treated samples were identified by means of micro-hardness and tensile tests. Microstructure of the weld and the fracture surface of the tension samples were investigated by optical and scanning electron microscopies. Fractographic evaluations were also performed by using scanning electron microscopy. According to the findings, due to the higher thermal conductivity and lower strength of the martensitic stainless steel, a larger upset and a broader heat affected zone are observed in the martensitic side. Furthermore, formation of non-tempered martensite with the maximum hardness of 880 HV in the heat affected zone (HAZ) of the martensitic stainless steel side makes the as-welded material susceptible to brittle fracture as detected by fractographic examinations. Nevertheless, a successful transition from brittle to ductile behavior is observed by the post-weld heat treatment at 760 ◦C for 60 min.