Analysis of Dissimilar in Metal Weld Formed by Transition Graded Method

Abstract

Dissimilar metal weld (DMW) joints found significant use in many applications such as power generation, nuclear reactors, chemical and petrochemical industry, cryogenic operations, automobile industry etc. This helps in getting tailor-made properties in components that are required in heterogeneous working conditions. Indeed joining of dissimilar metals has drawn to itself a great deal of interest in recent years due to difference in composition and properties of joining metals under common welding conditions. The stresses generated at the weld interface result in premature failure of joint in many applications. The present research investigates dissimilar metal welds of SA335 P11 and SA312 TP304 formed by conventional Gas Tungsten Arc Welding (GTAW) and Gas Metal Arc Welding (GMAW) processes. In order to understand the effect of heat treatment on these joints, one set each was heat-treated. The tensile test, hardness measurement and microscopic observations were carried out on as welded and heat-treated samples to understand the behavior of joints. newlineThe finite element analysis was carried out on three-dimensional model of transition-graded joint using Ansys software. The geometry of transition graded joint was kept same as the conventionally welded joint. The linear grading of properties in transition zone was based on novel layered deposition technique, Laser Engineered Net Shaping (LENS). The effect of number of layers of deposition and width of transition zone on the residual stresses was investigated at different mechanical loads and temperatures. newlineThe results indicate that GTAW process produced high strength, defect free joint of these alloys. The decrease in ultimate strength was observed in GMAW joint due to lack of fusion during welding. FEA of transition graded joint showed significant decrease in the stresses developed compared to the welded joint formed by GTAW and GMAW processes. The significant decrease in stresses in transition zone was observed with increase in number of layers of deposition at 25oC