The main factors affecting the stress corrosion of aluminum alloy are environmental factors, metallurgical factors and stress factors. The three are interconnected and interacted with each other.

1. Environmental factors

The environmental factors that affect the stress corrosion of aluminum alloy include ion type, ion concentration, pH value of solution, oxygen and other gases, corrosion inhibitor, ambient temperature, environmental pressure and so on.

The stress corrosion of two kinds of aluminum alloy 2A12 and 7A04 in different atmospheric environment is studied. It is found that the stress corrosion sensitivity of aluminum alloy in different environment is different, and it is more sensitive in the marine environment. A large amount of salt is contained in the marine environment, and the Cl- will pass through the protective film on the surface of the aluminum alloy to enter the interior and cause corrosion to it.

The results show that when the mass concentration of HNO3 solution is between 20%~40%, the corrosion of aluminum alloy is aggravated, and the corrosion rate of aluminum alloy reaches the highest point when the concentration is about 35%. In the concentrated HNO3 solution, the stress corrosion of the aluminum alloy is not obvious. This is due to the formation of a dense layer of oxidation on the surface of the aluminum alloy. The membrane prevented the further corrosion of HNO3.

 

2. Metallurgical factor

The metallurgical factors mainly include the casting mode, the processing mode and the influence of the thermal stress corrosion. It is found that the cathodic polarization makes the stress corrosion sensitivity of the aluminum alloy increase, and the stress corrosion sensitivity of the friction stir welding is lower than that of the fusion welding.

It is generally considered that the 6061-T6 and 3004 aluminum alloy treated by proper treatment will not change the type of the surface film of aluminum alloy with the different SCC. metallurgical factors, and cause the internal microstructure and the change of the crystal structure of the aluminum alloy, thus affecting the electrochemical behavior and mechanical behavior of the aluminum alloy, which leads to the stress corrosion sensitivity of the aluminum alloy. Same.

 

3. Stress factor

Stress factors mainly include load type, load size, loading direction, loading speed, etc. as far as SCC is concerned, the direction of stress must be perpendicular to the grain boundary so that it can be separated. One of the key factors of stress corrosion is the stress action. Different stress effects will produce different effects, alternating stress and ring. Corrosion fatigue is produced by the common effect of the environment. It is usually different from the stress corrosion cracking produced by fixed stress. Usually, the corrosion fatigue is more serious than the result of stress corrosion. In addition, the different loading speed will also affect the sensitivity of stress corrosion of aluminum alloy.