| 總結: | The present study has investigated the influence of scandium additions on the structure and mechanical properties of AA2219 gas tungsten arc (GTA) weldments. Controlled amounts of scandium modified AA2319 fillers were introduced into the molten pool of AA2219 by predeposited cast inserts under different welding conditions in GTA welding. Full penetration GTA welds were prepared using alternating current. It was observed that grain size decreased with increasing amounts of scandium and gradual transformation from columnar to equiaxed grain morphology. The observed grain refinement was shown to result in an appreciable increase in fusion zone hardness, strength, and ductility. Room temperature hardness and tensile properties at different temperatures (room temperature, 100, 150, 200 and 250 C) of weldments in the as-welded condition were observed and correlated with microstructure. The results show that the welds subjected to post-weld aging treatment have displayed superior hardness and tensile strength. © 2012 Springer-Verlag London Limited.
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