运用 Gleeble-1500D 热模拟试验机对铸态 Al-Zn-Mg-Cu 高强铝合金进行高温拉伸实验，利用光学显微镜（OM）观察断口附近的微观组织，用扫描电子显微镜（SEM）观察断口形貌。结果表明，变形温度在340℃～420℃，应变速率为0.01 s -1时，随着温度升高，峰值应力、峰值应变、断裂应变、断面收缩率、延伸率均下降；变形温度为360℃，应变速率为0.1 s -1～1 s -1时，随着应变速率的增大，峰值应力、峰值应变均增大，断裂应变减小，断面收缩率和延伸率有下降的趋势。该合金高温拉伸过程中的软化机制主要为动态回复。高温拉伸的断口形貌为韧性断裂。断口表面的粗大脆硬相对材料的性能有严重影响。%Hot tensile experiments of as-cast Al-Zn-Mg-Cu high strength alloy were carried out by means of a Gleeble-1500D thermo-mechanical modeling simulator. Microstructures near the fractures and fractography were an-alyzed by Optical Microscope(OM)and Scanned Electron Microscope(SEM). The results indicate that peak stress,peak strain,fracture strain,area reduction and elongation rate decrease with increasing temperatures in the tempera-ture ranges of 340 ℃ ~ 420 ℃ and strain rate of 0. 01 s - 1 . Peak stress and peak strain increase with increasing strain rates;Fracture strain,area reduction and elongation decrease with increasing strain rates. Dynamic recovery dominants during the hot tensile. The mixed fracture of ductile fracture and brittle fracture was observed by ana-lyzed the hot tensile fractography. Coarse and brittle hard phases in the alloy have an important effects on hot ten-sile properties of the alloy.
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