锻压技术

应变速率对7050铝合金性能的影响及强化机理

英文标题：Influence of strain rate on properties for 7050 aluminum alloy and strengthening mechanism

作者：张鹏1 陈诚2 袁武华2

分类号：TG146.2

出版年,卷(期):页码：2021,46(10):225-232

摘要：

通过压机进行双道次压缩工艺，结合热处理，利用室温拉伸测试和微观组织表征方法，研究了应变速率对7050铝合金力学性能的影响，并在微观组织定量分析的基础上，研究了不同应变速率压缩时合金的强化机理。第1/2道次的应变速率由0.003 s-1/0.006 s-1增至0.1 s-1/0.2 s-1，平均晶粒尺寸由52 μm减小至36 μm，小角度晶界分数由47%降至37%，位错密度由2.50×1014 m-2降至1.68×1014 m-2，大角度晶界强化对屈服强度贡献值均为11 MPa，小角度晶界强化对屈服强度贡献值分别为5和4 MPa，位错强化对屈服强度贡献值由88 MPa降至69 MPa。结果表明：合金固溶时效后的强度随着应变速率的增加而减小；应变速率引起的合金强度变化主要由位错强化主导，大、小角度晶界对合金的强度变化影响不明显，且随着应变速率的增大，位错、大角度晶界、小角度晶界对合金屈服强度的贡献值之和减小，从而导致合金强度降低。

Through the double-pass compression process of press, combined with the heat treatment, the influences of strain rate on the mechanical properties of 7050 aluminum alloy were studied by room temperature tensile test and microstructure characterization method, and based on the quantitative analysis of microstructure, the strengthening mechanism of alloy during the compression at different strain rates was investigated. As the strain rates of the first/second pass increased from 0.003 s-1/0.006 s-1 to 0.1 s-1/0.2 s-1, the average grain size decreased from 52 μm to 36 μm, the small-angle grain boundary fraction decreased from 47% to 37%, the dislocation density reduced from 2.50×1014 m-2 to 1.68×1014 m-2, the contribution value of the large-angle grain boundary strengthening to the yield strength was 11 MPa, the contribution values of the small-angle grain boundary strengthening to the yield strength was 5 MPa and 4 MPa, respectively, and the contribution value of the dislocation strengthening to the yield strength decreased from 88 MPa to 69 MPa. The results show that the strength of alloy after solution-aging treatment decreases with the increasing of the strain rate, the strength change of alloy caused by the strain rate is mainly dominated by the dislocation strengthening, and the large-angle and small-angle grain boundaries have no obvious influence on the strength of alloy. As the strain rate increases, the sum of the contribution values for dislocations, large-angle grain boundary and small-angle grain boundary to the yield strength of alloy decreases resulting in a decrease in the strength of alloy.

基金项目：

作者简介：张鹏（1977-），男，博士研究生，高级工程师 E-mail：ezwhzp@163.com 通信作者：袁武华（1973-），男，博士，教授，博士生导师 E-mail：yuan46302@163.com

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