Effect of Quenching Rate and Pre-strain on the Strain Ageing Behaviors of 7075 Aluminum Alloys

Abstract

The mechanical properties of aluminum alloys are strongly dependent on the thermo-mechanical process so, the strain ageing behavior of 7075 Al-alloy was investigated in this study. A set of test pieces was solution heat treated at 480 °C for 2 h, water quenched (SHTWQ) then pre-strained for 8% in tension. The test samples were aged at 140 °C for 0.5, 1,2,3,4,6,8,10,12,24, 48, 72 and 96 h in a furnace. The other set of test samples were solution heat treated at 480 °C for 2 h, quenched in sand (SHTSQ) then pre-strained for 8% in tension. They were also aged at 140 °C for same intervals. The effect of strain ageing, on the mechanical properties of Al-alloy, was investigated by mean of hardness, and tensile tests. The results shown that, the quenching rate after solution heat treatment, ageing time and temperature, as well as pre-strain, play a very important role in the precipitationhardening associated with ageing process of the 7075 Al-alloy.

Effects of Aging Temperature, Time During Transition from Brittle to Ductile on Fracture Behavior of Zinc Coated AA7075

“…Karaaslan et al [19] have performed heat treatment on AA 7075specimens by quenching them in water for 6 seconds and aging at 130°C for 12 hrs and noticed decrement in hardness and ultimate strength and increment in impact toughness. Kaç ara and Guleryuzb [20] have studied the effect of quenching during solution heat treatment, ageing time, temperature of ageing and pre-strain on the mechanical properties of 7075 Al-alloy samples at 480°C for 2 h and then pre-strained for 8% in tension. Sato et al [21] have noticed an increase in the strength, yield strength, tensile strength and hardness of 7075 aluminum alloys when heat-treated at different aging durations at 140°C.…”

AA7075 Yaşlandırılmasında Farklı Ön Gerinmelerin Mekanik Özelliklere Etkilerinin İncelenmesi

“…Bunun nedeni ise ön gerinmenin artması halinde pekleşmenin de artmasından dolayıdır [30]. 7075 alüminyum alaşımına %8 ön gerinme uygulanıp 140 ºC sıcaklıklarda farklı sürelerde yaşlandırma işlemi yapıldığında ön gerinmenin çökelme sertleşmesinde önemli bir katkısı olduğu görülmektedir [31]. Mg-Zn-Y alaşımı, %3-5 ön gerinme işlemiyle 150 ºC yaşlandırma sıcaklığında farklı sürelerde yaşlandırmaya tabi tutulmuş ve ön gerinmenin artmasıyla mukavemet ve sertlik değerleri de artmıştır [32].…”

Effects of Pre-Strain on the Aging Behavior of Al 7075 Alloy for Hot-Stamping Capability

“…In practice, Kaçar and Güleryüz examined that aging time and temperature, quenching rate, and pre-strain show a critical influence on the strength of Al 7075 alloy [12]. Keci et al demonstrated that faster quenching rate provides higher yield strength without applying aging treatment, and the highest achieved yield strength was equivalent to the T6 strength of 528 MPa [13].…”