Effect of Heat Treatment on the Corrosion Behavior of Welded 7075 T6 Aluminum Alloy Without Filler Material

A study on the effect of heat treatment and welding condition on the corrosion behavior of 7075T6 Al alloy without material contribution has been investigated in 3.5% NaCl solution. Electrochemical techniques included potentiodynamic polarization curves, linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) measurements. Heat treatments included solubilized, retrogression and re-aging (rra), and T73. After that, specimens were welded by the Tungsten inert gas (TIG) method without filler. Corrosion tests showed that the corrosion rates were very similar for both the base metal and welding. However, for the base metal, the highest corrosion rate was exhibited for the solubilized condition, whereas for the welding it was for the T6 condition. All specimens were highly susceptible to localized type of corrosion where the second phases acted as cathodes and the surrounding matrix acted as active anodes.