Study on Microstructure and Properties of AA2024-T6I4 with Deep Cryogenic Treatment

This paper proposes a combined treatment of secondary aging (T6I4) and deep cryogenic treatment (DCT), which includes initial aging, DCT, and re-aging, to improve the limitations of secondary aging (T6I4) treatment on enhancing the mechanical properties of AA2024. The scanning electron microscopy and transmission electron microscopy (TEM) are used to observe the alloy's microstructure, and hardness measurements, tensile tests, friction and wear tests, intergranular corrosion tests, and electrochemical corrosion tests are used to determine the alloy's properties. On comparison with T6I4, AA2024-T6I4 with DCT for 1 h increases its hardness, tensile strength and wear resistance, as well as its corrosion resistance. A TEM analysis of AA2024-T6I4 with DCT for 1 h reveals uniform distribution of fine matrix precipitates, a small size difference, and discontinuous and fine grain boundary precipitates within the alloy.