( 1. 中南大学材料科学与工程学院， 长沙 410083;
2. 邵阳学院 机械工程系， 邵阳 422004;
3. 西南铝加工厂， 重庆 401326)
摘 要: 研究了分级固溶对7A04铝合金组织与性能的影响。 结果表明： 7A04铝合金在470℃, 5min+485℃, 9min固溶和140℃, 6h+150℃, 1h时效后的σb， σ0.2和δ5分别达到544.6MPa， 498.8MPa和11.1%。 金相观察发现， 短时分级固溶（470℃, 5min+485℃, 3~9min）的晶粒尺寸较485℃单级固溶的细小。断口扫描电镜观察表明： 分级固溶获得了典型的韧窝型断口。 X射线衍射分析结果表明： 470℃, 5min+485℃, 9min分级固溶后， 除少量Al2Cu外， MgZn2已完全溶解。 能谱分析表明：未溶相主要为富Fe和Cu的杂质相。 由于470℃， 5min+485℃， 9min分级固溶的晶粒比485℃单级固溶的细小，溶质过饱和度达到了500℃， 20min单级固溶的水平， 使得时效后的试样获得了最高的力学性能，达到了常规固溶工艺的性能水平。
关键字: 高强铝合金； 分级固溶； 组织； 性能
and mechanical properties of 7A04 aluminum alloy
（ 1. School of Materials Science and Engineering,
Central South University, Changsha 410083, China;
2. Department of Mechanical Engineering, Shaoyang Institute, Shaoyang 422004, China;
3. Southwestern Aluminum Ltd.Co., Chongqing 401326, China）
Abstract: The effects of progressive solution treatment on microstructure and mechanical properties of 7A04 aluminum alloy were investigated. Results indicate that after solutionized under condition of 470℃, 5min+485℃, 9min and subsequent aging process of 140℃, 6h+150℃, 1h, σb， σ0.2 and δ5 of 7A04 alloy reach 544.6MPa， 498.8MPa and 11.1% respectively. Metallography observation indicates that the grain size after short-time progressive solution treatment（470℃, 5min+485℃, 3-9min） is smaller than that after single-stage solution at 485℃. SEM observation indicates that the progressively solutionized sample in tension test behaves as typical dimpled fracture. X-ray diffraction analysis indicates that after progressive solution under the condition of 470℃, 5min+485℃, 9min, MgZn2 as main strengthening phase is totally dissolved except a small amount of Al2Cu. EDAX analysis indicates that the main undissolved phases are inclusions rich in Fe and Cu. Because the grain size of the sample progressively solutionized at 470℃, 5min+485℃, 9min is smaller than that of single-step solutionized at 485℃, the supersaturation degree of the progressivly solutionized sample reaches that of the sample single-step solutionized at 500℃, 20min, and obtains the highest mechanical properties after subsequent aging, which is equal to those got by traditional solution process.
Key words: high strength aluminum alloy; progressive solution; microstructure; property
