【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。更多还原

【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 ℃, 5 min+485 ℃, 9 min and subsequent aging process of 140 ℃, 6 h+150 ℃, 1 h, σ_b, σ_0.2 and δ₅ of 7A04 alloy reach 544.6 MPa, 498.8 MPa and 11.1% respectively. Metallography observation indicates that the grain size after short-time progressive solution treatment（470 ℃, 5 min+485 ℃, 39 min） 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 ℃, 5 min+485 ℃, 9 min, 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 ℃, 5 min+485 ℃, 9 min 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 ℃, 20 min, and obtains the highest mechanical properties after subsequent aging, which is equal to those got by traditional solution process.更多还原