Transformation of Mechanical Performance and Corrosion Susceptibility of Al-Zn-Mg Alloy through Varied Flame Rectifications

The mechanical properties and corrosion performance of Al-Zn-Mg alloy through varied flame rectifications was studied based on the intergranular corrosion, exfoliation corrosion experiment. The results showed that the flame rectification accelerated the corrosion susceptibility of Al-Zn-Mg alloy. And the maximum intergranular corrosion depth are detected with the value of 89 mm after three time of flame rectification. The tensile strength of Al-Zn-Mg alloy increased to 383 MPa after one time of flame rectification in 300 °C. Then there is no significant change of tensile strength of Al-Zn-Mg alloy with the increase of flame rectification times. The change of corrosion resistance of Al-Zn-Mg alloy with varied flame rectifications is mainly associated with the transformation of precipitates and grains. There is a notable increase in the precipitation of phases within the grains after one time of flame rectification at 300°C. However, after two times of flame rectification, a phenomenon of "redissolution" of precipitated phases occurs. After three times of flame rectification, small-sized new grains appear at the grain boundaries of the elongated grains within the correction area, which is the result of incomplete recrystallization in the alloy.