Preparation and properties of Co-Cr alloy denture by selective laser melting

The selective laser melting (SLM) process of cobalt-chromium alloy and the effects of heat treatment were examined in this study to aid in the development of Co-Cr alloy personalized medical products. The Taguchi test was performed to determine the laser power, scanning speed, and hatch distance. The best process parameters were selected by using the highest density: the optimum hatch distance was 0.08 mm; the scanning speed was 1110 mm s(-1); the laser power was 335W; the energy density at this time was 4.8 J mm(-2); and the density reached 99.18%. The hardness, tensile strength, and elongation of the Co-Cr alloys formed by SLM were 41.0 HRC, 1032 MPa, and 10%, respectively. Their original phases were mainly composed of gamma(fcc) and epsilon(hcp) phases, and the alloy's microstructure consisted of fine equiaxed crystal and columnar crystal. The solution treatment process occurred in the gamma -> epsilon phase transition, and the solution-aging process also produced a strengthening phase M23C6 (M = Co, Cr, Mo, W). With the treatment in solution for 1 h at 1150 degrees C integrated with 2 h of aging at 800 degrees C, the hardness, tensile strength, and elongation were increased by 6.1%, 35.9%, and 17.6%, respectively, and fully met the requirements of ASTM F75. The bonding strength of the metal-ceramic joint was determined to be 94.3 MPa in a three-point bending experiment.