In this study, ultra-fine grained (UFG) structure was produced in the stir zone (SZ) of AA6005-T6 alloy joints using friction stir processing (FSP) cooled by liquid nitrogen (N2). Conventional friction stir welding (FSW) was used to fabricate reference joints. The corrosion properties of the cooled joints were investigated by atmospheric corrosion tests. The corrosion exposures were carried out at a relative humidity (RH) of 95%, 400 ppm CO2 and at 22°C. The rapidly cooled joints exhibited exceptional corrosion resistance in both corrosion experiments as well as better mechanical properties compared to those of the FSWed joints. The better corrosion resistance of the quenched sample was attributed to the microstructural modification of the joint.