Effects of different backing gases on 2404 duplex stainless steel welds

Abstract

In our research butt welds were made on newly developed LDX 2404 lean duplex stainless steel grade with gas metal arc welding. For root protection three different backing gases were used: pure argon, 95 vol% nitrogen + 5 vol% hydrogen and pure nitrogen. In case of pure nitrogen backing the effect of different gas flow rates was also investigated. Based on our research, the nitrogen content in the backing gas resulted in increasing austenite content. The increasing nitrogen content in backing gas and the increasing austenite content resulted in increasing pitting corrosion resistance. The flow rate of the backing gas also has significant effect on the evolving microstructure and pitting corrosion resistance.