Effect of Grain Aspect Ratio on Quenching Sensitivity and Corrosion Resistance of 7475 Aluminum Alloy

Hot-rolled 7475 aluminum alloy plates with different thicknesses (3, 6, 18 mm) were subjected to water quenching (cooling rate of 480 °C · s⁻¹) and air quenching (cooling rate of 2 °C · s⁻¹), followed by aging treatment, and the specimens with different grain size were obtained. The effect of grain aspect ratio on quenching sensitivity and corrosion resistance of specimens was investigated. The results show that under different quenching cooling rates and different thicknesses, the grains on the rolled surface of the test alloy core exhibited elongated morphology. With the increase of the thickness of the hot-rolled plate or the decrease of quenching cooling rate, the grain aspect ratio on the rolled surface of the core and the number of fine phases formed around the second phases increased. With the increase of grain aspect ratio, the electrical conductivity of the alloy was improved, the hardness decreased, and the quenching sensitivity index increased; the maximum corrosion depth increased, indicating the deterioration of intergranular corrosion resistance.