高培洪 许道奎 王硕 王东亮 吕鑫. 高密度超细孪晶结构对轧制态AZ80镁合金力学各向异性的影响[J]. 金属学报, DOI: 10.11900/0412.1961.2025.00160.

摘要 相关文章 Metrics 全文: PDF(3159 KB)   摘要: AZ80镁合金在室温多向锻压过程中所形成的高密度超细孪晶可显著提升合金的力学性能，但其对合金力学各向异性的影响仍有待研究。本工作基于微观组织表征、力学性能测试和失效分析等方法，本工作研究了室温多向锻压技术对轧制态AZ80镁合金中高密度超细孪晶的形成及力学各向异性的影响规律。微观组织观察结果表明，轧制态样品RD (轧向)-TD (横向)、ND (法向)-TD和ND-RD取向表面测得的平均晶粒尺寸分别为15.7、16.2和18.5 μm。室温下经在单道次6%应变条件下多向锻压6道次后，基体晶粒内形成了大量高密度超细孪晶，合金样品RD-TD、ND-TD和ND-RD取向表面上测得的平均晶粒尺寸分别减小至3.1、2.8和3.5 μm。同时，高密度超细孪晶的形成不仅弱化了合金的基面织构强度，还可使晶粒的c轴向RD的偏转角度大于TD。力学性能测试结果表明，高密度超细孪晶的形成可显著提升轧制态合金样品的力学性能，但表现出明显的力学各向异性。其中，轧制态合金样品沿RD的屈服强度、抗拉强度和延伸率分别为132 MPa、303 MPa和15.4%，沿TD分别为138 MPa、302 MPa和14.5%。经多向锻压后，合金样品沿RD的屈服强度、抗拉强度和延伸率分别为259 MPa、357 MPa和8.8%，沿TD则分别为361 MPa、459 MPa和6.4%。失效分析结果表明，轧制态合金样品沿RD和TD拉伸时，微裂纹主要萌生于孪晶界，多向锻压态合金样品的微裂纹主要萌生于晶界。 关键词 ： 变形镁合金,  多向锻压,  超细孪晶,  力学各向异性,  裂纹萌生     Abstract：Magnesium alloys, as low-cost commercial metallic materials with light weight, low density, good castability, and dimensional stability, are widely used in lightweight industries such as transportation and aerospace. However, the traditional hot deformation process limits the performance enhancement of magnesium alloys, significantly restricting their industrial applications. Through a novel multidirectional forging (MDF) process, tensile twins can be introduced to the maximum extent, effectively refining the grain structure and markedly improving mechanical strength. However, the twin structure may alter the texture, further affecting mechanical anisotropy. In this work, microstructural characterization, tensile testing, and failure analysis were conducted to investigate the effects of high-density ultrafine twins, formed via the MDF technique, on the mechanical anisotropy of as-rolled AZ80 Mg alloy. Microstructural observation shows that the average grain sizes of the rolling direction–transverse direction (RD–TD), normal direction (ND)–TD, and ND–RD surfaces for the as-rolled sample are 15.7, 16.2, and 18.5 μm, respectively. After six passes of MDF under a single-pass strain of 6% at room temperature (25 ℃), high-density ultrafine twins were formed within the grains, and the average grain sizes of the RD–TD, ND–TD, and ND–RD surfaces of the MDF-processed sample were reduced to 3.1, 2.8, and 3.5 μm, respectively. The formation of high-density ultrafine twins not only weakens the basal texture intensity but also causes the c-axis of grains to deflect by a larger angle with respect to RD than to TD. Tensile testing demonstrates that the introduction of such twins significantly improves mechanical properties but induces pronounced mechanical anisotropy. For the as-rolled samples, the yield strength (YS), ultimate tensile strength (UTS), and elongation (EL) along RD are 132, 303 MPa, and 15.4%, respectively, whereas along TD they are 138, 302 MPa, and 14.5%. After MDF, the YS, UTS, and EL along RD are 259, 357 MPa, and 8.8%, while along TD they are 361, 459 MPa, and 6.4%, respectively. Failure analysis indicates that, in the as-rolled samples tested along RD and TD, microcracks preferentially initiate at twin boundaries, whereas in MDF-processed samples, microcracks mainly occur at grain boundaries. Key words： Mg alloy    multi-directional forging    ultrafine twins    mechanical anisotropy    crack initiation 收稿日期: 2025-06-09      基金资助:国家自然科学基金 服务 把本文推荐给朋友 加入引用管理器 E-mail Alert RSS 作者相关文章 高培洪 许道奎 王硕 王东亮 吕鑫 44.8K 链接本文: https://www.ams.org.cn/CN/Y0/V/I/0 [1] 周雯慧, 熊锦涛, 黄思程, 王鹏昊, 刘勇. AZ31镁合金双峰组织形成机制及其变形行为[J]. 金属学报, 2025, 61(3): 488-498. [2] 王升, 朱彦丞, 潘虎成, 李景仁, 曾志浩, 秦高梧. Yb含量对Mg-Gd-Y-Zn-Zr合金微观组织与力学性能的影响[J]. 金属学报, 2025, 61(3): 499-508. [3] 程福来, 罗雪梅, 胡炳利, 张滨, 张广平. 锂离子电池用微米厚度超薄集流体Cu箔和Al箔疲劳强度及损伤行为[J]. 金属学报, 2024, 60(4): 522-536. [4] 李景仁, 谢东升, 张栋栋, 谢红波, 潘虎成, 任玉平, 秦高梧. 新型低合金化高强Mg-0.2Ce-0.2Ca合金挤压过程中的组织演变机理[J]. 金属学报, 2023, 59(8): 1087-1096. [5] 常立涛. 压水堆主回路高温水中奥氏体不锈钢加工表面的腐蚀与应力腐蚀裂纹萌生：研究进展及展望[J]. 金属学报, 2023, 59(2): 191-204. [6] 李细锋, 李天乐, 安大勇, 吴会平, 陈劼实, 陈军. 钛合金及其扩散焊疲劳特性研究进展[J]. 金属学报, 2022, 58(4): 473-485. [7] 王慧远, 夏楠, 布如宇, 王珵, 查敏, 杨治政. 低合金化高性能变形镁合金研究现状及展望[J]. 金属学报, 2021, 57(11): 1429-1437. [8] 王晋, 张跃飞, 马晋遥, 李吉学, 张泽. Inconel 740H合金原位高温拉伸微裂纹萌生扩展研究[J]. 金属学报, 2017, 53(12): 1627-1635. [9] 张子龙, 夏爽, 曹伟, 李慧, 周邦新, 白琴. 晶界特征对316不锈钢沿晶应力腐蚀开裂裂纹萌生的影响*[J]. 金属学报, 2016, 52(3): 313-319. [10] 王莉,周忠娇,张少华,降向冬,楼琅洪,张健. 镍基单晶高温合金冷热循环过程中圆孔周围裂纹萌生与扩展行为[J]. 金属学报, 2015, 51(10): 1273-1278. [11] 余龙, 宋西平, 张敏, 李宏良, 焦泽辉, 于慧臣. 高铌TiAl合金在疲劳蠕变作用下的裂纹萌生及扩展[J]. 金属学报, 2014, 50(10): 1253-1259. [12] 王志英 王俭秋 韩恩厚 柯伟 闫茂成 张峻巍 刘楚威. 涂层剥离条件下X70管线钢的应力腐蚀裂纹萌生行为[J]. 金属学报, 2012, 48(10): 1267-1272. [13] 洪友士 赵爱国 钱桂安. 合金材料超高周疲劳行为的基本特征和影响因素[J]. 金属学报, 2009, 45(7): 769-780. [14] 陈竹兵 黄志伟 王中光 朱世杰. 涂覆Ni--Cr--Al--Y涂层的镍基高温合金热机械疲劳行为[J]. 金属学报, 2009, 45(7): 820-825. [15] 钱桂安 洪友士. 环境介质对40Cr结构钢高周和超高周疲劳行为的影响[J]. 金属学报, 2009, 45(11): 1356-1363. Viewed Full text Abstract Cited   Shared      Discussed