Enhancement of mechanical properties of alloy steel by GTAW with different purge/shielding gases

Abstract

Welding of ferritic steel tube material T91 (9Cr-1Mo), was used because of high temperature withstanding, mechanical properties, compatibility with chemicals and adequate weldability. The main objective of this project is to find out near optimum welding parameters with appropriate shielding gas in gas tungsten inert gas welding (GTAW) of T91 tube. The quality and productivity of the weld joint strongly depends on welding parameters. The perfect arc during welding is produced when the welder uses the optimum welding parameters. The composition of shielding gas plays an important role ensuring sound quality of welds. The composition of shielding gas with the molten pool has a marginal influence in the depth of penetration. The optimized parameters with three samples were prepared with different purging gases Viz. 100% helium, 100% Argon, Argon 50% plus Helium 50% for welding of 2.9 mm thick T91 tube with ER 505 filler wire.

Taguchi Grey Relational Analysis of Mechanical Properties of Structural Steel Welding Made by Gas Tungsten Arc Welding

“…The failure at the edge of the welding region due to the softening of HAZ is believed to be caused by increased heat input, which led to increased strains in the welding area, even if the dilution wasn't higher for the experiments that were exposed to lower heat input. It was stated that HAZ has larger residual stresses than the welding area [28] , and its softening is the cause of the hardness loss [29] .…”

Specifities of application of activating fluxes in electrical welding in protective atmosphere

“…For conventional arc welding process the composition of shielding gas plays an important role ensuring the quality of welds, but has a marginal influence on the depth of arc penetration [1]. The application of activating flux during welding increases the depth of penetration 2-3 times without increasing the heat input of welding [2][3][4][5][6][7][8].…”