Microstructure of conventional/PBF-LB/M 316L stainless steel hybrid joints brazed with nickel-based brazing alloys

Abstract

Due to the additive manufacturing principle, laser-melted materials (PBF-LB/M) such as the austenitic chromium-nickel steel 316L have a different microstructure compared to materials produced by conventional continuous casting. The PBF-LB/M-produced 316L has a thermally metastable, anisotropic microstructure with epitaxially grown grains in which a cellular substructure is located. When brazing hybrid joints from the conventional and additive manufacturing routes with nickel-based brazing alloys, different diffusion mechanisms occur simultaneously in both joining partners. This occurs due to the different microstructural characteristics of the parent materials. The altered diffusion mechanisms lead to a new distinct microstructure in the joining zone, which influences the achievable quality of the brazed joint in a previously unknown way.