Microstructure evolution, martensite transformation and mechanical properties of heat treated Co-Cr-Mo-W alloys by selective laser melting

The influence of laser energy density and heat treatment on the microstructure and properties of Co-Cr-Mo-W alloys fabricated by selective laser melting (SLM) are investigated symmetrically. When the laser power, the scanning speed, and the scanning space are set as 160 W, 400 mm/s, and 0.07 mm, respectively, the SLM-ed Co-Cr-Mo-W alloys display high strength and good ductility simultaneously. The precipitates ranging from nano-to macro-scale are finely distributed in SLM-ed Co-Cr alloys grains and/or along the grain boundaries in the heat treated alloys. Co-Cr-Mo-W alloys with an excellent combination of strength and ductility can be achieved by tailoring the microstructure and morphology of SLM-ed alloys during the heat treatment. The tensile strength, yield strength, and elongation are 1221.38 +/- 10 MPa, 778.81 +/- 12 MPa, and 17.2 +/- 0.67%, respectively.