文章摘要
王思军,李宁,郗学奎.2024-T3铝合金的动态断裂韧性[J].精密成形工程,2017,9(4):72-78.
WANG Si-jun,LI Ning,XI Xue-kui.Dynamic Fractural Toughness of 2024-T3 Aluminum Alloy[J].Journal of Netshape Forming Engineering,2017,9(4):72-78.
2024-T3铝合金的动态断裂韧性
Dynamic Fractural Toughness of 2024-T3 Aluminum Alloy
投稿时间:2017-05-02  修订日期:2017-07-10
DOI:10.3969/j.issn.1674-6457.2017.04.013
中文关键词: 铝合金  加载速率  动态断裂韧性  断面分析
英文关键词: aluminum alloy  loading rate  dynamic fracture toughness  fracture analysis
基金项目:国家重点基础研究发展计划(973)(2011CB012806)
作者单位
王思军 华中科技大学 材料科学与工程学院武汉 430074 
李宁 华中科技大学 材料科学与工程学院武汉 430074 
郗学奎 中国科学院物理研究所北京 100190 
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中文摘要:
      目的 实现2024-T3铝合金动态断裂韧性的测量,揭示加载速率对动态断裂韧性的影响机理。方法 采用屏蔽措施避免电磁干扰,测量2024-T3铝合金在不同加载速率下的动态断裂韧性,采用扫描电子显微镜(SEM)观察断口形貌,理论分析加载速率对动态断裂韧性的影响机理。结果 当加载速率小于103 MPa•m1/2•s-1时,2024-T3铝合金的动态断裂韧性约为35 MPa•m1/2;当加载速率高于105 MPa•m1/2•s-1时,动态断裂韧性超过40 MPa•m1/2,且随加载速率的增加而不断增大至101 MPa•m1/2。断口分析表明,加载速率较低时,断口形貌为微孔聚集型;当加载速率超过105 MPa•m1/2•s-1时,断口特征由延性韧窝向准解理形态转变。理论分析表明,上述现象主要是由于裂纹尖端的无位错区域尺寸随加载速率的增大而减小,位错对裂纹尖端应力场的屏蔽效应增大,从而导致裂纹起裂后迅速由韧窝状态向准解理状态转变。结论 电磁屏蔽后的电阻应变片法,能够准确测量电磁环境下2024-T3铝合金的动态断裂韧性,且动态断裂韧性表现出明显的应变率敏感性;2024-T3铝合金的微观断裂机制在准静态下为微孔聚集型,加载速率超过105 MPa•m1/2•s-1时,材料的断裂表现为由延性韧窝形态向准解理形态转变。
英文摘要:
      The paper aims to measure the dynamic fracture toughness of aluminum alloy, probe effects of loading rate on dynamic fracture toughness and understand the corresponding mechanism. The dynamic fracture toughness of 2024-T3 aluminum alloy under various loading rates was systematically measured by shielding the electromagnetic interference. The fractural morphology was characterized by Scanning Electron Microscope (SEM), and the effect of loading rate on dynamic fracture toughness was understood through theoretical analysis. The dynamic fracture toughness was about 35 MPa•m1/2 when the loading rate was less than 103 MPa•m1/2•s-1. As the loading rate was higher than 105 MPa•m1/2•s-1, the dynamic fracture toughness was over 40 MPa•m1/2, and increased with increasing loading rate up to 101 MPa•m1/2. The fracture morphology was microporous aggregation at low loading rate. The fracture feature changed from ductile dimple to quasi-cleavage morphological when the loading rate exceeded 105 MPa•m1/2•s-1. The above phenomenon was mainly caused by that the crack tip of the dislocation area size decreased with the increase of loading rate, the dislocation of the crack tip stress field shielding effect became larger, resulting in crack initiation rapidly changing from the dimple state to the quasi-cleavage state. The dynamic fracture toughness of 2024-T3 aluminum alloy can be measured accurately by shielding the electromagnetic interference, and the dynamic fracture toughness is sensitive to the loading rate. The fracture morphology is microporous aggregation at low loading rate, but it transfers from ductile dimple to quasi-cleavage morphological when the loading rate exceeds 105 MPa•m1/2•s-1.
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