Compositionally graded magnetic-nonmagnetic bimetallic structure using laser engineered net shaping

Fabrication of compositionally-graded magnetic-nonmagnetic bimetallic structures was successfully completed using a laser engineered net shaping (LENS™) system. A graded magnetic functionality was implemented by directly transitioning from non-magnetic austenitic stainless steel 316 (SS316) to magnetic ferritic stainless steel 430 (SS430) in a single structure. LENS™ additive manufacturing utilizes a high-powered laser to continuously melt and bond metallic powder in successive layers to create the 3D structure. Microstructures revealed a preferred grain growth direction at the interfaces of the deposited layers. Micro-hardness values across the part's cross-section exhibited a smooth transition from the highest value of 266 ± 4 HV in the SS430 region to the lowest value at the SS316 substrate of 174 ± 3 HV. Magnetic functionality was observed on the SS430 side of the bimetallic structure, showing how LENS™ can additively combine materials of varying compositions for location-specific functionality.