Characterization of Dissimilar Joints Between Hastelloy C276 Nickel Alloy and AISI 316L Austenitic Stainless Steel

Abstract

Abstract In this study, the microstructural features and mechanical properties of dissimilar joints between Hastelloy C276 and AISI 316L by gas tungsten arc welding were characterized. ERNiCrMo-4, a Ni-Cr-Mo based filler metal, was used and the welding was performed by multi-pass. Both macro and microstructural features of joints were examined using microscopic techniques. Macrostructural characterization revealed no defects like cracking, pores and undercuts within the joints. The microstructure of weld metal had several forms of solidified austenitic matrix and P phases embedded in dendritic structure. Partially melted zones were observed at the fusion line between the weld metal and AISI 316L and grain growth was determined within the fusion line between the weld metal and Hastelloy C276. In mechanical characterization, not only the variation of hardness but also mechanical properties under tensile and impact loadings were investigated as a function of microstructural features of the joint. The hardness profile throughout the dissimilar joint had a gradual increase from AISI 316L to Hastelloy C276, both having polygonal grains and hardness values of the weld metal strongly affected its solidified form. Due to the superior mechanical properties of Hastelloy C276, failure under tensile loading occurred within AISI 316L. Under impact loading, heat affected zone of Hastelloy C276 showed the highest impact strength.