EFFECT OF CONTROLLED QUENCHING ON THE AGING OF 2024 ALUMINUM ALLOY CONTAINING BORON

The presence of alloying elements, sometimes in a very small amount, affects mechanical properties; one ofthese elements is boron. in aluminum industries, boron master alloy is widely used as a grain refiner in this research,the production process of aluminum –boron master alloy was studied at first; then, it was concurrently added to 2024aluminum alloy. after rolling and homogenizing the resulting alloy, the optimal temperature and time of aging weredetermined during the precipitation hardening heat treatment by controlled quenching (t6c). then, in order to findthe effect of controlled quenching, different cycles of heat treatment including precipitation heat treatment bycontrolled quenching (t6c) and conventional quenching (t6) were applied on the alloy at the aging temperature of110°c. mechanical properties of the resulting alloy were evaluated after aging at optimum temperature of 110°c byperforming mechanical tests including hardness and tensile tests. the results of hardness test showed that applying thecontrolled quenching instead of conventional quenching in precipitation heat treatment caused reduction in the timeof reaching the maximum hardness and also increase in hardness rate due to the generated thermo-elastic stressesrather than hydrostatic stresses and increased atomic diffusion coefficient as well. tensile test results demonstratedthat, due to the presence of boride particles in the microstructure of the present alloy, the ultimate tensile strength inthe specimens containing boron additive increased by 3.40% in comparison with the specimens without such anadditive and elongation (percentage of relative length increase) which approximately increased by 38.80% due to therole of boron in the increase of alloy ductility.