Stainless steel to titanium bimetallic structure using LENS™

Laser Engineered Net Shaping (LENS™) is a commercially available additive manufacturing technique that was used for one step manufacturing of bimetallic structures of stainless steel and Ti6Al4V (Ti64) alloy. Two approaches were adopted for manufacturing these bimetallic structures. In the first approach, direct deposition of Ti64 on SS410 substrate and compositionally graded bimetallic structures were attempted without any intermediate bond layer. In the second approach, an intermediate NiCr bond layer (of thickness ∼750 μm) was deposited to minimize thermal and residual stresses for these bimetallic structures. Direct deposition of Ti64 was successful only for a couple of layers before the structures were delaminated. Compositionally graded bonding was unsuccessful with the formation of brittle intermetallics and related residual stresses causing delamination. Using an intermediate NiCr layer, bimetallic structures were successfully fabricated. Our work is focused on LENS™ based processing approach and related microstructural evolution towards bimetallic structures.