Microstructure and mechanical properties analysis of S30408 joints by PAW plus GTAW hybrid welding

The S30408 austenitic stainless steels were welded by the plasma arc welding (PAW) and the gas tungsten arc welding (GTAW), the microstructure evolution of the welded joint was characterized and analyzed by the scanning electron microscope (SEM) and the electron backscatter diffraction (EBSD). In order to research the mechanical properties of the welded joints, tensile and low-temperature Charpy impact tests were carried out, the impact fractures were studied by SEM; the grain sizes of the weld seam (WS) were fine, consisting primarily of the austenite and the ferrite; under the low heat input, the high tensile strength and elongation were achieved due to the fine grain strengthening; the fracture of hybrid welded joints attributed to the mixed mode of the ductile also brittle fracture.