ارتقاء خواص مكانيكي و مقاومت به خوردگي تنشي آلومينيوم 7075 به وسيله نورد و عمليات پيرسازي دو مرحله اي

Improvement of Mechanical Properties and SCC Resistance of Al-7075 by Rolling and Two Steps Aging

Two steps aging is a novel heat treatment for 7000 series a Aluminum which improves the stress corrosion cracking (SCC) resistance of these alloys without any considerable influence on their strength. The heat treatment included a post - quenching pre - strain of 5%, a high - temperature aging at 200 C for several minutes and a subsequent low - temperature aging at 120°C for 24 h as conventional T6 treatment. This research concentrates on improvement of this heat treatment for Al-7075 alloy. One stage rolling prior to high temperature aging and also one stage before the second step of aging resulted in simultaneous increasing the strength and SCC resistance of the alloy similar to those obtained by T6 and T73 treatments respectively. Strain induced at the first step of rolling caused more forming r| phase particles and the second rolling led to breaking the grain boundary precipitates and increasing the anodic surfaces which subsequently reduced the dissolution of the particles.