|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Magnesium Technology 2017
||I-54: Grain Refining in Mg Welds with Arc Oscillation
||Tao Yuan, Shujun Chen, Sindo Kou
|On-Site Speaker (Planned)
Grain refining can improve the solidification-cracking resistance during welding and mechanical properties of the resultant weld. AZ31 Mg and AZ91 Mg alloy were welded by gas-tungsten arc welding with arc oscillation (transverse, longitude and circular) at 1 Hz frequency and 2 mm amplitude. Significant grain refining was achieved with all 3 different kinds of oscillation. The following observations were made. First, the grain refining of AZ31 Mg welds increased with increasing oscillation frequency. However, grain refining disappeared when the frequency exceeded 25Hz. Second, the grain refining of AZ91 Mg welds was more significant than AZ31 Mg welds. Third, the grain refining mechanism was identified as dendrite fragmentation, instead of heterogeneous nucleation or grain detachment. Fourth, transverse arc oscillation not only caused dendrite fragmentation but also increased constitutional supercooling.