Issue 24

H. S. Patil et alii, Frattura ed Integrità Strutturale, 24 (2013) 151-160; DOI: 10.3221/IGF-ESIS.24.16 158 the corrosion resistance is very poor. The poor pitting corrosion resistance of weld joint is due to difference in pitting potentials across the weld region or stir nugget because of inhomogeneity of microstructures in those regions. With AA6082 on the advancing side, the corrosion rate is higher with respect to increasing welding speed of the tool while corrosion rate decreased in case of AA6061 on advancing side (Tab. 5). Such dependence of the corrosion behaviour on the material position was observed. All FSW samples show passivation after longer time of exposure to corrosion media. AA6082-61 at 62mm/min has highest active potential (-1.16V). The active E corr increased with increasing the weld speed in case advancing and retreating side of 6082T6-6061T6. Figure 10 : SEM images of tensile fracture surface of 6061-6082 at 62mm/min. Material of FSW Joint I corr (µA/cm 2 ) E corr (mV) Corrosion Rate (mpy) 6082T 6 -6061T 6 55.00 -938 25.14 6082T 6 -6061T 6 3.33 -1160 1.520 6061T 6 -6082T 6 836nA -732 382 e -3 6061T 6 -6082T 6 1.590 -920 726.60 e -3 AA6082-T 6 4.270 -1380 1.95 AA6061-T 6 1.820 -1160 832.1 e -3 Table 5: Result analysis of corrosion test. Figure 11 : Polarization curves of base metals AA6082 and AA6061