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TC21钛合金拉伸和冲击韧性的内在控制机理研究
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1.长江大学物理与光电工程学院;2.长江大学机械工程学院;3.长安大学材料科学与工程学院

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国家自然科学基金资助(项目号52101122);湖北省高等学校优秀中青年科技创新团队计划项目(项目号T2020008)


Intrinsic control mechanism of tensile and impact toughness of TC21 titanium alloy
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1.School of Physics and Optoelectronic Engineering,Yangtze University,Jingzhou;2.School of Material Science and Engineering,Chang’an University,Xi’an

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    摘要:

    TC21合金具备较高的强度和断裂韧性,然而其拉伸和冲击韧性的内在控制机理差异还不明确。本文通过调控固溶温度和冷却速率制备出不同显微组织,研究其拉伸和冲击性能。结果表明,拉伸和冲击韧性表现出不同的变化规律,塑性较好的双态组织的冲击韧性比塑性最差的全片层组织的冲击韧性低,说明拉伸性能和冲击韧性的内在控制机理有所不同,时效后的性能(时效后塑性无明显变化但冲击韧性显著下降)进一步证实了这一点。拉伸变形时,试样在发生颈缩前整个区域均发生塑性变形,双态组织中αp和βt之间发生的协调变形得以充分发挥,而全片层组织集束尺寸较大且其内部片层α取向一致,位错滑移长度较大,易发生塑性应变局域化,造成其强塑性匹配差于双态组织。冲击时,高应变速率作用下裂纹在缺口根部快速萌生和扩展,塑性变形集中在裂纹尖端附近小范围内,造成双态组织中αp和βt之间的协调变形不能充分发挥,而全片层组织的集束尺寸较大,导致集束界面对塑性变形的影响较小,此时片层α和β成为控制塑性变形的有效单元,粗片层α和β具有较好的塑性变形能力,造成其获得较高的萌生功,和拉伸表现出较差的塑性相悖,此外,大角度α集束界面造成裂纹偏转而形成曲折的路径,最终造成其冲击韧性高于双态组织。为获得拉伸性能和冲击韧性的良好匹配,可通过热处理调制出由含量较少的αp和内部形成粗大片层α和β的βt所构成的双态组织。

    Abstract:

    TC21 alloy has high strength and fracture toughness, however, the mechanism of crack initiation and propagation during impact is not clear, and the relationship between impact toughness and tensile properties is yet to be studied. In this work, different microstructures are prepared by regulating the solid solution temperature and cooling rate to study the tensile and impact properties. The results show that tensile performance and impact toughness exhibit different variation laws. The impact toughness of the bimodal structure with better plasticity is lower than that of the full lamellar structure with the worst plasticity, indicating that the intrinsic control mechanisms of tensile properties and impact toughness are different, which is further confirmed by the post-aging properties (no significant change in plasticity but significant decrease in impact toughness after aging). During tensile deformation, plastic deformation occurs in the whole region of the specimen before necking occurs, and the coordination deformation between αp and βt in the bimodal structure is fully developed, while the full lamellar structure has a larger colony size and its internal lamellar α orientation is uniform, and the dislocation slip length is larger, making it susceptible to plastic strain localization, resulting in a poorer strength plasticity matching than that of the bimodal structure. Under the influence of high strain rate, the crack initiation and propagation at the notch root are rapid, and the plastic deformation is concentrated in a small range near the crack tip, resulting in the coordination deformation between αp and βt cannot be fully played. In this case, the colony interface of the full lamellar structure has little influence on the plastic deformation, and the lamellar α and β become the control units of plastic deformation. The coarse lamellar α/β has better plastic deformation ability, resulting in higher crack initiation energy, contrary to the poor plasticity exhibited by stretching. In addition, the large angle interface of α colony causes the deflection of cracks and forms a tortuous path, resulting in higher impact toughness than the bimodal structure.

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引用本文

雷磊,朱琦玮,赵秦阳,赵永庆. TC21钛合金拉伸和冲击韧性的内在控制机理研究[J].稀有金属材料与工程,2024,53(5):1449~1457.[Lei Lei, Zhu Qiwei, Zhao Qinyang, Zhao Yongqing. Intrinsic control mechanism of tensile and impact toughness of TC21 titanium alloy[J]. Rare Metal Materials and Engineering,2024,53(5):1449~1457.]
DOI:10.12442/j. issn.1002-185X.20230266

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历史
  • 收稿日期:2023-05-06
  • 最后修改日期:2023-06-12
  • 录用日期:2023-06-26
  • 在线发布日期: 2024-05-28
  • 出版日期: 2024-05-22