Mechanical properties and microstructural features of rotary friction welded UNS S42000 martensitic stainless-steel joints

Abstract

Abstract The main objective of this investigation is to study the mechanical properties and microstructural features of rotary friction welded (RFW) UNS S42000 martensitic stainless-steel joints. The welded joints were stress relieved at 316 °C for 1 h holding followed by air cooling. The joints welded using the friction pressure of 60 MPa, forging pressure of 64 MPa, friction time of 18 s and forging time of 4 s exhibited superior tensile properties. Microstructure showed carbide precipitates and strain induced and partial strain induced martensite in weld zone for heat treated condition and coarser martensite and retained austenite for non-heat treated condition. Fractography for tensile tested samples reveals predominantly ductile mode of fracture for heat treated samples than non-heat treated condition. The Microhardness showed a higher value of hardness for the weld zone due to strain induced martensite and lesser hardness at PDZ due to partial strain hardened martensite.