Grain Refinement Enhanced Tensile Strength, Fracture Toughness and Fatigue Crack Propagation Resistance of a High Zn-Containing Al-Zn-Mg-Cu Alloy

Q4 Physics and Astronomy Defect and Diffusion Forum Pub Date : 2023-05-08 DOI:10.4028/p-pzkzok

Haibo Lin, Kai Wen, Xi Wu Li, Hua-Min Zhou, Ya Nan Li, B. Xiong

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Abstract

In present work, a high Zn-containing Al-Zn-Mg-Cu alloy with different grain sizes was fabricated by extrusion and related precipitation characteristics and mechanical property were investigated after uniform heat treatments. The results showed that precipitation characteristics for the three alloys were almost the same. Matrix precipitates were GPII zone and η' phase and possessed small size and dense distribution while grain boundary precipitates exhibited discontinuous distribution. The rank of strength and fracture toughness for the three alloys are SG>MG>LG. Tearing ridges had been found on all the fracture surface while only LG alloy possess obvious dimple characteristics. The a-N curve showed that crack length list is MG>LG >SG under a same cycle number. The da/dN-ΔK curve also proved that fatigue crack propagation (FCP) rate of MG alloy is slightly larger than that of LG alloy, both were apparently larger than that of SG alloy. The width of fatigue striations on FCP fracture surface also backed it. Besides, obvious transgranular cracking characteristics and apparent secondary cracks were found on the FCP fracture surface.

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晶粒细化提高了高含锌Al-Zn-Mg-Cu合金的抗拉强度、断裂韧性和抗疲劳裂纹扩展性能

采用挤压法制备了不同晶粒尺寸的高含锌Al-Zn-Mg-Cu合金，并对其均匀热处理后的析出特性和力学性能进行了研究。结果表明，三种合金的析出特征基本相同。基体析出相为GPII区和η相，尺寸小，分布致密，晶界析出相呈不连续分布。三种合金的强度和断裂韧性等级分别为SG、>、MG、>、LG。所有断口表面都有撕裂纹，只有LG合金具有明显的韧窝特征。a- n曲线显示，相同循环次数下，裂纹长度表为MG>LG >SG。da/dN-ΔK曲线也证明MG合金的疲劳裂纹扩展速率略大于LG合金，两者均明显大于SG合金。FCP断口上疲劳条纹的宽度也支持了这一结论。此外，FCP断口表面有明显的穿晶开裂特征和明显的次生裂纹。

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Defect and Diffusion Forum Physics and Astronomy-Radiation

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1.20

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0.00%

发文量

127

期刊介绍： Defect and Diffusion Forum (formerly Part A of ''''Diffusion and Defect Data'''') is designed for publication of up-to-date scientific research and applied aspects in the area of formation and dissemination of defects in solid materials, including the phenomena of diffusion. In addition to the traditional topic of mass diffusion, the journal is open to papers from the area of heat transfer in solids, liquids and gases, materials and substances. All papers are peer-reviewed and edited. Members of Editorial Boards and Associate Editors are invited to submit papers for publication in “Defect and Diffusion Forum” . Authors retain the right to publish an extended and significantly updated version in another periodical.