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通过对7075铝合金进行不同温度(450~495℃)的固溶处理,研究了固溶温度对该合金的硬度、室温拉伸性能及高周疲劳性能的影响,并用光学显微镜和扫描电镜对合金显微组织及疲劳断口进行观察。结果表明,随着固溶温度的升高,合金组织发生不同程度的静态再结晶和晶粒长大,合金硬度和拉伸强度均先升高后降低,480℃固溶处理后达到最高;疲劳极限随着固溶温度的升高先降低后升高,495℃固溶处理后达到最高。疲劳裂纹主要起源于粗大残留相处,扩展过程中产生的二次裂纹可降低裂纹扩展的驱动力,进而降低合金的裂纹扩展速率,提高合金疲劳性能。
The effects of solution temperature on the hardness, tensile properties at room temperature and high cycle fatigue properties of 7075 aluminum alloy were investigated by solution heat treatment at different temperatures (450 ~ 495 ℃). The microstructure of the alloy Microstructure and fatigue fracture were observed. The results show that with the increase of solution temperature, the static recrystallization and grain growth occur in different degrees. The hardness and tensile strength of the alloy first increase and then decrease, reaching the highest after solution treatment at 480 ℃. Fatigue The limit first decreases and then increases with the increase of solution temperature, reaching the highest after solution treatment at 495 ℃. The fatigue crack mainly originated from the coarse residual phase. The secondary crack generated during the expansion process can reduce the driving force of crack propagation, and then reduce the crack propagation rate and improve the fatigue properties of the alloy.