Improving the strength-ductility synergy and impact toughness of dissimilar martensitic-austenitic steel joints by A-TIG welding with wire feed

Abstract

Activated flux-tungsten inert gas (A-TIG) weld joint of dissimilar martensitic-austenitic steel possesses low strength-ductility synergy and poor impact toughness due to the formation of hard and brittle martensitic structure in the weld zone (WZ). In the present work, a pathway is proposed to improve the strength-ductility synergy and impact toughness of such dissimilar weld joints by feeding the ErNiCrMo-3 wire into the weld pool during welding. ‘A-TIG welding with wire feed’ (patent pending*) successfully modified the WZ chemical composition (Creq: 15.01 and Nieq: 28.16), which altered its microstructure from hard and brittle martensite to Fe-Ni-Cr rich soft austenite. As a result, a superior strength-ductility synergy (ultimate tensile strength: 684.9 MPa and elongation: 45.8%) and unprecedented impact toughness (89 ± 2.4 J) was achieved.