Abstract
This work focuses on the analysis of the compositional variation made during stir casting of Al-B4C metal matrix composite (MMC) and the properties of GTA weldments. Pulsed current gas tungsten arc (GTA) welding, a novel variant of traditional GTA weld process, was tried on two different composites, viz. 2 % and 4 % B4C particulates in aluminium matrix. For a chosen current and voltage, two different pulsing frequencies (2Hz & 5Hz) were combined with three different pulse on time periods (40%, 50 % & 60%) and the weldments were compared with that of constant current weldments. An attempt has been made to study the time-temperature effect of pulsed GTA welding process parameters on microhardness in as-welded condition. Pulsed current resulted in better grain refinement and the same is reflected in the microhardness values. The increase in the reinforcing composition showed increased effect on the fusion zone weld hardness levels. Increase in Pulse on time and pulse frequency of PC weldments resulted in increased hardness of both the compositions.
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