The Effects of Gas Tungsten Arch Welding on the Corrosion and Mechanical Properties of AA 6061 T6

Corrosion of welded and un-welded Aluminum Alloy 6061 T6 was investigated by immersing specimens in 3.5% (wt) NaCl solution. Potentiodynamic and open circuit potential measurements were conducted. The mechanical properties were investigated using tensile strength, hardness, and torsion tests. Optical Microscopy and Scanning Electron Microscopy were used to investigate the microstructure evolution and the failure pattern of the specimens. Results revealed that corrosion current of the heat affected zone (HAZ) was higher than the base metal (BM). Corrosion potential for HAZ was more negative than the BM. Significant pitting corrosion was observed on the HAZ compared to the BM. Welding was found to weaken the mechanical properties of the alloy. Welded tensile specimens were failed at the welded area whereas not welded ones were failed at the centre. Welded torsion specimens were failed at the HAZ but not welded ones failed at the centre. The hardness of HAZ was decreased as a result of the heat generated during the welding process. Hardness values were increased as we moved away from the welded region.