Effect of heat treatment on the anisotropic microstructural and mechanical properties of Co-Cr-Mo alloys produced by selective laser melting.
Effect of heat treatment on the anisotropic microstructural and mechanical properties of Co-Cr-Mo alloys produced by selective laser melting.
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DOI：
10.1016/j.jmbbm.2019.103496
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发表时间：
2020-02
影响因子：
3.9
通讯作者：
Atsushi Takaichi;Yuka Kajima;Nuttaphon Kittikundecha;Hein Linn Htat;Hla Htoot Wai Cho;T. Hanawa;T. Yoneyama;N. Wakabayashi
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文献类型：
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作者：
Atsushi Takaichi;Yuka Kajima;Nuttaphon Kittikundecha;Hein Linn Htat;Hla Htoot Wai Cho;T. Hanawa;T. Yoneyama;N. Wakabayashi
本研究的目的是评估热处理对选择性激光熔化（SLM）制备的钴-铬-钼（Co-Cr-Mo）合金的显微组织和力学性能的各向异性的影响。哑铃样品被制造成轴线偏离构建方向0°（0°-样品）、45°（45°-样品）或90°（90°-样品），并在各种温度（750 ° C、900 ° C、1050 ° C或1150 °C）下进行热处理6小时。在750、900和1050 °C下热处理的样品中，微观结构表现出柱状晶粒，其<001>沿构建方向沿着具有纤维织构，与构建状态相同。力学性能表现出各向异性; 0°-样品的0.2%偏移屈服强度（YS）低于90°-样品的0.2%偏移屈服强度（YS），0°-样品的伸长率显著高于45°-和90°-样品的伸长率。而在1150 °C保温6 h的试样中，各向异性柱状晶完全消失，均出现了取向随机的等轴晶，表明发生了再结晶。此外，SLM过程中产生的特定微观结构和织构消失了。关于拉伸性能，由as-SLM样品表现出的初始强各向异性显著降低。因此，在再结晶温度下的热处理产生具有随机织构的均匀等轴晶粒，这有助于降低SLMed Co-Cr-Mo合金的机械各向异性。
The purpose of this study was to evaluate the effect of heat treatment on the anisotropy of the microstructure and mechanical properties of cobalt–chromium–molybdenum (Co–Cr–Mo) alloys fabricated by selective laser melting (SLM). Dumbbell samples were fabricated with the axes deviating from the build direction by 0° (0°-sample), 45° (45°-sample), or 90° (90°-sample) and were subjected to heat treatment at various temperatures (750, 900, 1050, or 1150 °C) for 6 h. In samples heat-treated at 750, 900, and 1050 °C, the microstructures exhibited columnar grains with a <001> fiber texture along the build direction, the same as in the as-built state. The mechanical properties showed anisotropy; the 0.2% offset yield strengths (YS) of the 0°-samples were lower than those of the 90°-samples, and the elongations of the 0°-samples were significantly higher than those of the 45°- and 90°-samples. By contrast, in samples heated to 1150 °C for 6 h, the anisotropic columnar grains completely disappeared, and equiaxed grains with random orientations were found in all samples, indicating that recrystallization had occurred. Moreover, the specific microstructures and texture generated during SLM disappeared. Regarding tensile properties, the initially strong anisotropy exhibited by the as-SLM samples was significantly reduced. Thus, heat treatment at the recrystallization temperature produced uniform equiaxed grains with random texture, which contributed to reducing the mechanical anisotropy of the SLMed Co–Cr–Mo alloys.