A study on influence of shielding gas composition on toughness of flux-cored arc weld of modified 9Cr–1Mo (P91) steel

In the present study, flux-cored arc welds of modified 9Cr–1Mo (P91) steel were produced using four types of shielding gases with rutile based flux-cored wire. Artificially prolonged post-weld heat treatment and GTAW surface melting methods improved the toughness of welds having high inclusion content. Fusion zone toughness was correlated with inclusion size and its distribution, shielding gas composition, chemical composition and post-weld heat treatment process parameters. It was found that 95% argon + 5% CO2 was the ideal shielding gas medium for FCA process to meet the toughness requirements with better process characteristics.