Interfacial microstructure and mechanical properties of 316L/CuSn10 multi-material bimetallic structure fabricated by selective laser melting

摘要

Selective laser melting (SLM) is a metal additive manufacturing (AM) technique that can fabricate complex parts of any shape. In this paper, the interfacial microstructure and mechanical properties of 316L/CuSn10 bimetallic structure were studied, and the ability of self-developed multi-material SLM equipment to form multi-material bimetallic structures was described. The investigations of 316L/CuSn10 bimetallic structure involved microscopic features, phase analysis, microhardness, tensile properties and bending properties. Moreover, the mechanical properties of multi-material specimens were compared with that of single material samples. In addition, scanning electron micrograph shows that the width of the bimetallic fusion zone is about 550 mu m, and dendritic crack sources was found on the boundary between the bimetallic fusion zone and the steel region. In the direction perpendicular to the interface, the Vickers microhardness value gradually changed from 233.1 +/- 8.1 HV in the steel zone to 154.7 +/- 6.0 HV in the bronze zone. The non-standard tensile samples were printed and tested for evaluating tensile properties, the ultimate strength of 316L/CuSn10 joint was 423.3 +/- 30.2 MPa comparing with the 316L stainless steel of 673.1 +/- 4.2 MPa and the CuSn10 Tin-bronze of 578.7 +/- 30.6 MPa. Tensile stress-strain curves and fracture characteristics show that the fusion zone of steel and bronze exhibits brittle fracture mechanism. Furthermore, three-point bending test was used to evaluate the interfacial bonding strength of the bimetallic structure, and results show that the maximum flexural strength of 316L/CuSn10 bimetallic structure isn't in middle of but below that of 316L stainless steel and CuSn10 Tin-bronze. The research founding that SLM can obtain 316L/CuSn10 bimetallic structure with good joint strength by adopting island scanning strategy and inter-layer stagger scanning strategy in the interfacial layers.