On the quantitative characterization of weld microstructures

A new technique to calculate spatial variations of grain shape, grain size, and grain boundary curvature in the fusion zone (FZ) of refractory metal alloys has been developed. This technique was applied to quantitatively evaluate changes in microstructures of simulated molybdenum welds available in the literature. Use of this technique showed that a 50% increase in weld speed more than doubled the fraction of grain segments oriented between 0° and 30° to the normal to the weld direction along with a decrease in grain size from approximately 120 µm to 84 µm in the weld direction at the FZ centerline. [Display omitted]