Abstract
Wrought aluminum alloy, A6016, was welded to cast aluminum alloy ADC12 by a friction stir welding (FSW) technique to fabricate dissimilar welds. A6016 was set on the advancing side, while ADC12 was on the retreating side. The tool offset was set to be ±1 mm from the join line. Fatigue strengths of dissimilar welds were lower than that of A6061, but higher than that of ADC12. Fatigue strength increased when the tool was offset into ADC12, which could be attributed to the decrease of risk volume containing casting defects. When ADC12 was set on the advancing side, the fatigue strength of dissimilar weld decreased. Microstructural observation revealed that the macroscopic structure in the stir zone (SZ) drastically changed by putting ADC12 on the advancing side, resulting in the lower fatigue crack initiation resistance and lower fatigue strength.
