Research 2205 Resistance Spot Welding Joints Microstructure And Mechanical Properties

Duplex stainless steels (DSSs), such as2205, have become importantalternatives to austenitic stainless steels in chloride environments because oftheir combination of high strength, resistance to localized corrosion, and stresscorrosion cracking. Their good properties rely on the duplex microstructure,which consists of approximately equivalent amounts of γ and α without otherundesirable precipitates. At present, the research on duplex stainless steelwelding performance is focused on the microstructure and performance offusion welding joints, but the overall performance of resistance spot welding ofduplex stainless steel joint research related reports are very few. This kind ofsheet material has a very wide range of applications. So research on theperformance of resistance spot welding of duplex stainless steel is urgentlyneeded. This paper focuses on2205duplex stainless steel plate as the researchobject, the resistance spot welded joint fracture microstructure andcharacteristics, influence of process parameters on the properties of spot weldingjoints and optimization of welding parameters by the Taguchi method have beenstudied, results show that:The fracture of2205duplex stainless steel spot welding joints mainlycontains two types, namely button fracture and joint fracture, the button fractureis the main fracture type. The fracture starting position of button fracture mainlyshows characteristics of the plastic deformation, distributing some dimple. Whenthe welding pressure is0.6MPa, the welding current is9.5kA, the welding timeis200ms, the fracture shape of weld joints is button fracture which torn alongthe base metal region, micro fracture shows the emergence of a large number ofdimples, which belongs to the ductile fracture.Welding pressure, welding current and welding time are the mainparameters which influence2205duplex stainless steel welding joint properties：When welding pressure increases from0.5MPa to0.6MPa, welding currentincreases from7.4kA to9.5kA, welding time increases from180ms to200ms,the joint structure grains become smaller, joint shear strength become stronger and the nugget diameter become large, the microhardness decreases. But whenthe welding pressure is too large (0.7MPa), welding time is too long (220ms),the joint shear strength decreases, when the current is too large (11.6kA), thejoint shear strength decreases and the welding process produces a large splash,resulting in joint tissue shrinkage defects.The Taguchi experimental analysis shows, the effects on the joint bearingcapacity of1mm thickness2205duplex stainless steel from big to small arewelding current、welding time、welding pressure, the welding current has asignificant effect on the joint bearing capacity, welding time and weldingpressure on the joint bearing capacity are not significantly effect. Optimizationof Taguchi method results for the welding current9.5kA、welding time200ms、welding pressure0.6MPa,3groups2205duplex stainless steel were welded byusing three-phase inverter resistance welding machine with the welding current9.5kA、welding time200ms、welding pressure0.6MPa, and then measured thejoint maximum shear for15.028kN, the optimal results increased2.27%thanbefore.