Mn Content And Thermomechanical Processing Of 2519a Aluminum Alloy Microstructure And Properties

This paper combines "aluminum alloy Impact Dynamic behavior of the structure and characteristics of micro-down" which is belong to the 973 Project "efficient utilization of high-performance aluminum and aluminum resources in basic research". By scanning electron microscopy (SEM), transmission electron microscopy(TEM), x-ray diffraction (XRD) analysis, optical microscopy, the tensile test, and hardness testing method, the content of element Mn and thermomechanical treatment affect 2519A aluminum alloy on the microstructure and mechanical properties of the experimental results showed:1. The element Mn puts effect on the age hardening behavior of 2519A aluminum alloy, when the content of Mn is 0.18%, the effect of age hardening is weak; while the content of Mn is 0.29%, it is at the peak, its peak hardness is 127HV; as the content of Mn is 0.44%, the effect of aged hardening decreases. Appropriate content of Mn is in favor of the increase of thernal stability of theθ' phase. The hardening effect is accelerated with the increases of Mn, simultaneously, the time up to the peak of age hardening reduces.2. When the content of Mn of 2519A aluminum alloy is 0.29%, after solution heat treatment at 525℃for 1.5h and ageing heat treatment at 165℃for 9h, the mechanical properties of alloy at room temperature areσb=459MPa,σ0.2=405MPa,δ=13.6%.3. The observation of SEM showed that, after the T6 heat treatment of the 2519A aluminum alloy containing 0.29% Mn, a large amount of even and fineθ' phase were precipitated in intergranular, whileθphase on grain boundaries was distributed and precipitation-free zone was narrow.4. The orthogonal experimentd indicate that, the best thermomechanical treatments process of the 2519A aluminum alloy containing 0.29% Mn are:solution treatment at 525℃for 1.5h,50% pre-deformation and aging at 140℃for 6 hours.5. The mechaical properties of 2519A aluminum alloy containing 0.29% Mn areσb=551MPa,σ0.2=507MPa,δ=7.8%, after solution treatment at 525℃for 1.5h, water-cooling,50% deformation, spent 6 hours at 140℃.6. The observation of SEM demonstrates that, the 2519A aluminum alloy containing 0.29% Mn after solution heat treatment at 525℃for 1.5h,15% pre-deformation and aging at 140℃for 6 hours, finedθ' phase distributes homogenously in intergranular, the size ofθ'phase is 20-30nm,while precipitation-free zone at grain boundaries was narrow, only about 30 nm.