Huang Hualong, Zhang Taomei, Chen Chao, Hosseini Seyed Reza Elmi, Zhang Jiaqi, Zhou Kechao
State Key Laboratory of Powder Metallurgy, Powder Metallurgy Research Institute, Central South University, Changsha 410083, China.
School of Metallurgy and Materials Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran 13114-16846, Iran.
Materials (Basel). 2022 Aug 10;15(16):5493. doi: 10.3390/ma15165493.
In this work, the anisotropic microstructure and mechanical properties of selective laser melted (SLMed) Ti-5Al-5Mo-5V-1Cr-1Fe (Ti-55511) alloy before and after aging treatment are investigated. Owing to the unique thermal gradient, the prior columnar β grains with {001} texture component grow in the building direction, and the mechanical properties of the as-fabricated Ti-55511 alloy exhibit slight anisotropy. Aging treatment creates uniform precipitation of the α phase at the boundaries as well as the interior of β grains. Due to the microstructure of the aged samples with a weak texture, the mechanical properties exhibit almost isotropic characteristics with an ultimate tensile strength of 1133 to 1166 MPa, yield strength of 1093 to 1123 MPa, and elongation from 13 to 16%, which meet the aerospace allowable specification very well. By XRD and EBSD analyses, the total dislocation density of the aged samples (134.8 × 10 m) is significantly lower than that of the as-fabricated samples (259.4 × 10 m); however, the aged samples exhibit a higher geometrically necessary dislocation (GND) density (28.5 × 10 m) compared with the as-fabricated samples GND density (2.9 × 10 m). Thus, a new approach to strengthening theory for estimating the anisotropic mechanical properties of AM alloys is proposed.
在这项工作中，研究了选择性激光熔化（SLMed）的Ti-5Al-5Mo-5V-1Cr-1Fe（Ti-55511）合金在时效处理前后的各向异性微观结构和力学性能。由于独特的热梯度，具有{001}织构组分的柱状初生β晶粒沿构建方向生长，增材制造态Ti-55511合金的力学性能表现出轻微的各向异性。时效处理使α相在β晶粒的边界以及内部均匀析出。由于时效态样品的微观结构织构较弱，其力学性能表现出几乎各向同性的特征，极限抗拉强度为1133至1166MPa，屈服强度为1093至1123MPa，伸长率为13%至16%，非常符合航空航天允许规范。通过XRD和EBSD分析，时效态样品的总位错密度（134.8×10 m）明显低于增材制造态样品（259.4×10 m）；然而，与增材制造态样品的几何必要位错（GND）密度（2.9×10 m）相比，时效态样品表现出更高的GND密度（28.5×10 m）。因此，提出了一种新的强化理论方法来估算增材制造合金的各向异性力学性能。
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