时效制度对AA6156铝合金拉伸性能和断裂韧性的影响

Effects of Aging Treatments on Tensile Properties and Fracture Toughness of AA6156 Aluminum Alloy

摘要:

研究了AA6156铝合金在不同时效状态下的拉伸性能和平面应力断裂韧性。结果表明：AA6156合金薄板在自然时效态下断裂韧性最好，但强度偏低；在190 ℃单级峰时效和175 ℃/6 h+190 ℃/13 h双级过时效态下强度较好，但断裂韧性偏低；而在175 ℃/2 h+200 ℃/0.5 h双级时效态下达到较理想的强韧性匹配。由透射电镜和扫描电镜观察其微观组织及断口形貌得出：双级时效时，第一级预时效处理能增大GP区的析出数量，从而在后续第二级时效时极大地促进β″相更密集、更均匀地析出。时效制度对AA6156合金断裂韧性的影响主要取决于晶内析出相β″，而受晶界微观组织结构的影响较小

Abstract:

The tensile properties and plane-stress fracture toughness of AA6156 aluminum alloy with different aging treatments were studied. The results show that the natural aged AA6156 alloy obtains perfect fracture toughness, while a lower strength. The AA6156 alloy in single peak aging at 175 oC and in 175 oC/6 h+190 oC/13 h duplex over aging can both offer preferable strength, while lower fracture toughness. The property of the alloy can achieve the superior combination of the strength and toughness under 175 oC/2 h+200 oC/0.5 h aging conditions. Microstructure observations indicate that pre-aged treatment can increase the quantity of GP-zones, thus promoting homogeneous precipitation of β″ phase in the following aging treatments. The effect of aging treatments on fracture toughness of AA6156 alloy mainly depends on the strengthening phase β″ in the matrix, whereas grain boundary microstructures have less effect on it