Effect of non-isothermal aging on mechanical properties, corrosion behavior and microstructure of 7075 aluminum alloy

The effect of the maximum temperature of non -isothermal aging on the properties of 7075 aluminum alloy was investigated by hardness, friction and wear, as well as intergranular and electrochemical corrosion tests. The results show that when the maximum temperature is 190 degrees C, the hardness of the alloy is the highest when cooled to 100 degrees C, which is 183.5 HV. The wear rate is minimal at 4.5 x 10 -3 mm 3 m -1 , the mechanical properties exceed that of T6 tempering. The TEM images show that in the high -temperature stage, as the temperature increases, the large -size precipitated phases increase, resulting in a decrease in the mechanical properties of the alloy, and in the cooling stage, "secondary precipitation" as well as the phenomenon of back dissolution occurs. At the same time, the grain boundary precipitation phases of T max 190 sample were intermittently distributed and staggered, forming the appropriate width of the precipitation -free zone (PFZ). The depth of intergranular corrosion is only 20.1 mu m, i corr and V corr are 0.61 x 10 -3 mA/cm 2 and 0.0198 mm/a, respectively, and the corrosion resistance exceeds that of T73 tempering, while the time is greatly shortened to improve efficiency.