Mechanical Properties of Cobalt Chromium Alloy Manufactured by Direct Energy Deposition Technology

Abstract

Cobalt chromium (CoCr), a well-known biocompatible material, is additively manufactured using direct energy deposition (DED) technology in this study. This study investigates some important mechanical characteristics of the additively manufactured CoCr using two different numerical simulation methods in addition to mechanical tests and experiments. Mechanical experiments such as hardness, wear, and flexural bending test were conducted on DED-processed samples. All experiments were also conducted on conventionally processed CoCr specimens for comparison purposes. DED-processed CoCr samples exhibited a complex microstructure with a variety of features such as cellular, columnar, and equiaxed grains within their melt pools. While the DED-processed sample had a lower hardness compared to the conventionally processed one, it exhibited a higher wear resistance. The tensile strength obtained from resonance frequency testing was higher for the DED-processed CoCr sample compared to the conventionally fabricated one. The out-of-plane mechanical strength of CoCr samples was measured by conducting flexural bending test, and the conventional sample showed a higher flexural modulus than the DED sample. The bend tests were also numerically simulated using two different finite element analysis (FEA) procedures. The FEA results for the conventionally processed samples are in good agreement with the ones obtained from the experimental flexural bending test. The results of the FEA studies on the DED-processed samples were within 10-20 % of the experimental ones, showing the potential of numerical methods in estimating this property without the need of mechanical testing.