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 335 W; 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 γ(fcc) and e(hcp) phases, and the alloy's microstructure consisted of fine equiaxed crystal and columnar crystal. The solution treatment process occurred in the γ → e 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 °C integrated with 2 h of aging at 800 °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.