Microstructure and mechanical properties of A-TIG welded AISI 316L SS-Alloy 800 dissimilar metal joint

TLDR: In this article, the microstructure and mechanical properties of dissimilar metal weld joints between AISI 316L SS-Alloy 800 developed by activated TIG (A-TIG) welding are discussed.

Abstract: The present work discusses the microstructure and mechanical properties of dissimilar metal weld joint between AISI 316L SS-Alloy 800 developed by activated TIG (A-TIG) welding. The evolution of fusion zone microstructure and solidification temperature range were investigated through equilibrium calculation and Scheil-Gulliver equation. Electron probe micro-analysis revealed the micro-segregation of Ti and Si in the inter-dendritic arms of the fusion zone. The presence of secondary phases (Ti(C,N) and FeSi2) in the fusion zone was confirmed with X-ray diffraction technique and transmission electron microscopy of electrochemically extracted precipitates. The A-TIG weld joint showed a decent combination of tensile strength and impact toughness. Tensile testing with digital image correlation revealed a transfer of strain localization from Alloy 800 side heat affected zone to the fusion zone due to lower hardening capacity of the fusion zone. During tensile loading, the formation of micro-cracks along the solidification grain boundaries reduces the peak tensile strength of the fusion zone.