Influence of titanium–boron additions on grain refinement of AA6082 gas tungsten arc welds

Grain refinement of weld metal plays a vital role in improving mechanical properties (ductility and toughness) as well as weldability. The present study has investigated the influence of Tibor (TM) additions on the structure and mechanical properties of AA6082 gas tungsten arc (GTA) weldments. Controlled amounts of Tibor (TM) grain refiner (containing Ti and B in a ratio of 5: 1) were introduced into the molten pool of AA6082 by pre-deposited cast inserts (AA4043 and AA5356) under different welding conditions by GTA welding. Full penetration GTA welds were prepared using alternating current (AC). It was observed that grain size was decreased with increasing amounts of Tibor (TM). The grain refinement is mainly caused grain nucleation associated with constitutional undercooling during solidification. It has been shown that welds prepared with 5356 cast insert exhibited high strength and ductility when compared with other welds. The observed grain refinement was shown to result in an appreciable increase in fusion zone hardness, strength and ductility. (C) 2012 Elsevier Ltd. All rights reserved.