Abstract
The effect of the electromagnetic vibration of the arc and the influence of current pulses on the microstructure of welded tantalum sheets were investigated. Optimum conditions of arc vibration and of current pulses for refined microstructure in the fusion zone and in the heat-affected zone (HAZ) were determined. At these conditions equiaxed grains in the fusion zone and a decreased grain size in the HAZ were obtained. The effect of the welding rate on the microstructure was also investigated. Mechanical properties of the welds with improved microstructure obtained by the above techniques were compared with the properties of welds obtained by conventional TIG techniques and with those of the parent metal. Slight improvement in yield stress and tensile stress and significant improvement in elongation were observed in the improved welds, compared to welds obtained by conventional techniques.
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