Effect of laser rescanning on microstructure and mechanical properties of direct energy deposited AISI 316L stainless steel

Abstract

Laser direct energy deposition (LDED) process has gained substantial relevance owing to their capability of manufacturing complex parts via the layer-by-layer joining of materials. AISI 316L stainless steel is one of the most widely investigated materials for use in the LDED process. The aim of this study is to explore the effect of laser rescanning (i.e. additional laser scanning on solidified layers prior to depositions of next layers) on microstructure and mechanical property of direct energy deposited 316L alloy. A 316L alloy was fabricated by LDED with laser rescanning and its microstructure and mechanical properties were compared to those of the same alloy fabricated without the laser rescanning process. The results revealed that the laser rescanning improves significantly the mechanical properties of the 316L alloy produced by the LDED. In comparison to the alloy without laser rescanning treatment, the yield strength was improved by more than 1.2 times and the ultimate tensile strength was increased by 1.1–1.15 times with the laser rescanning treatment. The alloy treated by the laser rescanning showed also superior ductility than that without the treatment. Thus, the laser rescanning process seems very promising as a way of improving the mechanical properties of the 316L alloy fabricated by the LDED.