Wire arc additive manufacturing of ER70S-6/S355 bimetal component

Abstract

Among the various fusion-based additive manufacturing processes, wire arc additive manufacturing (WAAM) has the highest deposition rate, which is beneficial for fabricating large volume components. The WAAM process usually begins with printing on a substrate, that could act as a functional part of the component. To study the possibilities of fabricating multimaterial structure, a highly dense ER70S-6 was directly fabricated on an S355 substrate using the WAAM process. Microstructural studies revealed a good fusion and bonding at the interface. Equiaxed grains were observed in the plasma WAAM process fabricated ER70S-6 and the interface. For the as-built condition, the WAAM-built ER70S-6/S355 bimetal joint has a yield strength of 349 MPa; a UTS of 503.5 MPa; and an elongation of 30%. The yield strength and UTS of WAAM-built ER70S-6 and as-received S355 are close. The fracture occurs on the S355 side of the as-built ER70S-6/S355 bimetal joint because the as-built ER70S-6 has a higher elongation than S355 (40.2% vs 33.2%). After quenching heat treatment, the WAAM-built ER70S-6/S355 bimetal joint has a yield strength of 511.6 MPa; a UTS of 740.7 MPa; and an elongation of 20.1%. The fracture occurs on the ER70S-6 side because it has a low yield strength and UTS. This work demonstrates that dissimilar substrate can be used for WAAM process to fabricate multimaterial structures.