Localized corrosion and stress corrosion cracking resistance of friction stir welded aluminum alloy 5454

The susceptibility of welded and unwelded samples of Al 5454 (UNS A95454) i n the -O and -H34 tempers to pitting corrosion and stress corrosion crackin g (SCC) in chloride solutions was studied. Welded samples were fabricated u sing the relatively new friction stir welding (FSW) process as well as a st andard gas-tungsten are welding process for comparison. Fitting corrosion w as assessed through potentiodynamic polarization experiments. U-bend and sl ow strain rate tests were used to determine SCC resistance. The FSW samples exhibited superior resistance to pitting corrosion compared to the base me tal and are-welded samples. U-bend tests indicated adequate SCC resistance for the FSW samples. However, the FSW samples exhibited discontinuities tha t probably were associated with remnant boundaries of the original plates. These defects resulted in intermittent increased susceptibility to pitting and, particularly for Al 5454-H34 samples, poor mechanical properties in ge neral.