Takaichi Atsushi, Kajima Yuka, Kittikundecha Nuttaphon, Htat Hein Linn, Wai Cho Hla Htoot, Hanawa Takao, Yoneyama Takayuki, Wakabayashi Noriyuki
Removable Partial Prosthodontics, Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan.
Removable Partial Prosthodontics, Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan; Department of Dental Materials, Nihon University School of Dentistry, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo, 101-8310, Japan.
J Mech Behav Biomed Mater. 2020 Feb;102:103496. doi: 10.1016/j.jmbbm.2019.103496. Epub 2019 Oct 17.
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.
本研究的目的是评估热处理对通过选择性激光熔化（SLM）制造的钴铬钼（Co-Cr-Mo）合金微观结构和力学性能各向异性的影响。制备了哑铃形样品，其轴线与构建方向的偏差分别为0°（0°样品）、45°（45°样品）或90°（90°样品），并在不同温度（750、900、1050或1150 °C）下进行6小时的热处理。在750、900和1050 °C下热处理的样品中，微观结构呈现出沿构建方向具有<001>纤维织构的柱状晶粒，与原始状态相同。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，且0°样品的伸长率显著高于45°和90°样品。相比之下，在加热至1150 °C持续6小时的样品中，各向异性的柱状晶粒完全消失，所有样品中均发现了取向随机的等轴晶粒，这表明发生了再结晶。此外，SLM过程中产生的特定微观结构和织构消失。关于拉伸性能，SLM态样品最初表现出的强烈各向异性显著降低。因此，在再结晶温度下进行热处理产生了具有随机织构的均匀等轴晶粒，这有助于降低SLM制备的Co-Cr-Mo合金的力学各向异性。
