R V College Of Engineering, India
Title: Investigation on weldability behavior of chromium-free nickel filler with stainless steel AISI-304
Biography: Nataraj J R
Two novel Cr-free nickel based welding filler rods were fabricated and used to weld austenitic grade stainless steel 304 (SS304) by tungsten inert gas (TIG) welding. Two welding wires designated as 3S (without Mn) and 4N (with 2% Mn) of %wt composition 43.499Ni, 25Fe, 10Mo, 10Cu, 10Co, 0-2 Mn, 1Ti, 0.5Al and 0.001C were fabricated and welded to SS304. Comparative studies of the joints welded by these two filler rods are presented. The weld joints were characterized for microstructure, mechanical and fracture properties. The microstructure of the weld interface showed presence of TiC and MoC precipitates within the grains and along the grain boundaries which is attributed for its strength of the weld joints. The Unmixed zone in the joint welded by 3S filler rod is wider than that welded with 4N filler rod. Presence of 2% Mn in 4N filler rod promotes the formation of γ' (gamma prime) precipitates and hence may be responsible for better joint strength than joints welded by 3S filler rod. Tensile tests results showed joint strength due to 4N filler rod is marginally superior (by 3.5%) to joints welded by 3S filler rod. However the ductility of the joint welded by 4N filler rod was lower by 6% compared to the joint welded by 3S filler rod. The hardness across the weld joints showed softer heat affected zone (HAZ) and hence is susceptible for failure during mechanical loading. The joint welded with 4N filler rod underwent significant amount of plastic deformation before failure. The joints welded with both the filler rods showed ductile mode of failure.