Evaluations of Surface Integrity and Mechanical Performance in Laser Melting of Stainless Steel Powders with Heterogeneous Metal Substrates

Abstract

This paper outlines advances in the processing technology of layer manufacturing in conjunction with laser melting metallic powders (stainless steel 316L) on heterogeneous metal substrates (stainless steel 316). Elemental migration of chromium and nickel in the fusion/dilution zone which led to possible strengthening mechanisms was analysed. Two-phase austenitic microstructures in the body were found to dilute into the stainless steel 316 substrate matrixes leading to the strengthening in the conjunction. Laser power was shown to be particularly significant (Fcal: 6.03, PCR: 47.9%) to produce high microhardness (~268 HV0.1) depending on the increase in ferrite content. In the confirmation runs, high tensile strength was achieved (834 MPa) with high density (7.64 g/cm3) due to the smoothened elemental migration of chrome and nickel, the strengthened matrix in the duplex structure, and the enhanced microhardness under the input high energy density.