The evaluation of mechanical properties of dissimilar welded AISI 347 stainless steel to ASTM A335 low alloy steel

In this study, the mechanical properties of dissimilar welding of austenitic stainless steel AISI 347 to low alloy steel ASTM A335 prepared by gas tungsten arc welding process using direct current electrode negative polarity have been investigated. For this purpose, two filler metals including ER309L and ERNiCr-3 were used. In order to achieve suitable structure and excellent mechanical properties in the mentioned joints, controlling of the heat input and preheating were among the effective and controllable parameters. The microstructure of the base metals and weld metals, were evaluated using optical microscopy and scanning electron microscopy was used to analyze fracture surface. Microstructural evaluations showed that a two-phase structure consisting of dendritic and inter-dendritic regions with primary austenite solidification in ERNiCr-3 weld metal, and the primary skeleton-shaped ferrite with austenitic matrix in the 309L weld metal was observed. Also mechanical properties including the bend test, ultimate strength, impact resistance and hardness were investigated. All the specimen underwent ductile fracture in HAZ in the tension test. The maximum fracture energy related to the ERNiCr-3 the welded specimen. The maximum and minimum hardness corresponded to the ERNICr-3 and ER309L, respectively. Finally, it can be calculated that for the joints, between the austenitic stainless steel AISI 347 to low alloy steel A335, the ERNICr-3 filler provided the optimum qualities.