Effect of building direction on the mechanical anisotropy of biocompatible Co-Cr-Mo alloy manufactured by selective laser melting process

초록

The present study investigated the effect of building direction on the microstructure and mechanical anisotropy of Co-Cr-Mo alloys fabricated via selective laser melting process. When manufactured vertically to the initial base plate (BD sample), yield strength and tensile strength were found to be relatively low, but elongation high. By contrast, when produced horizontally to the base plate (PD sample), the yield strength and tensile strength were relatively high, but elongation was as low as 3%. In the BD sample, (001)[001] texture tilting 3-20 degrees from the building direction was mainly observed. The PD sample showed random texture. To interpret the effect of texture on strength, yield strength was estimated and compared using Taylor factor concept and extreme lower bound concept. As a result, the extreme lower bound model (representative Schmid factor) was found to give a more accurate yield strength value for the highly textured microstructure (BD sample). Since the BD sample had crystallographic direction that could accept plastic deformation easily, the sample showed significant strain induced martensitic transformation. Based on these, the plastic elongation of the BD sample had a greater value than that of the PD sample, where the strain hardening rate remained constant. (c) 2020 Elsevier B.V. All rights reserved.

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