(1. 中南大学 轻合金研究院，长沙 410083；
2. 中南大学 材料科学与工程学院，长沙 410083)
摘 要: 为了研究6082铝合金锻件亚结构组织演变对力学性能的影响，本文在不同应变速率下，对6082铝合金进行锻造试验，通过EBSD和TEM表征，探讨不同热处理条件下锻件的亚晶体积分数和位错密度对析出强化的影响。结果表明：变形温度为490 ℃时，随着应变速率的增加，6082铝合金变形组织内亚晶和位错密度不断增加，再结晶程度却不断下降。在后续热处理过程中，亚结构作为析出相的有利形核点诱导形核，析出相直径随着位错密度的增加而减小，且间距变小，数量密度增加。同时，位错密度和亚晶体积分数对析出强化的贡献呈线性关系，共同影响着析出相的强化效果，二者达到平衡时总强化效果最好，即在 为0.3 s-1热变形时，(550 ℃、1 h固溶)+(180 ℃、12 h)人工时效热处理后，锻件的屈服强度达到331.4 MPa，伸长率为9.9%。
关键字: 6082铝合金；锻压；位错密度；亚结构；析出强化
（1. Research Institute of Light Alloy, Central South University, Changsha 410083, China;
2. School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:To study the influence of substructure evolution on mechanical properties of 6082 aluminum alloy forgings, the forging tests of 6082 aluminum alloy were carried out at different strain rates. By means of EBSD and TEM characterization, the effects of subgrain volume fraction and dislocation density on precipitation strengthening were investigated under different heat treatment conditions. The results show that, when the deformation temperature is 490 ℃, the density of subgrain and dislocation in the deformed microstructure of 6082 aluminum alloy increases with the increase of strain rate, while the degree of recrystallization decreases continuously. During the subsequent heat treatment process, the substructure acts as the favorable nucleation point to induce the nucleation of the precipitated phase, and the precipitation diameter decreases with the increase of dislocation density, and the spacing becomes smaller, and the quantity density increases. At the same time, the contribution of dislocation density and subgrain volume fraction to the precipitation strengthening is linear, which affects the strengthening effect of the precipitation. When both two strength contributions reach the balance, the mechanical properties are the best after (550 ℃, 1 h solid solution)+(180 ℃, 12 h) artificial aging heat treatment, the yield strength reaches 331.4 MPa, and the elongation is 9.9%.
Key words: 6082 aluminum alloy; forging; dislocation density; substructure; precipitation strengthening
