Grain Refinement of Aluminum Weld Metal Titanium and zirconium microadditions have a strong influence on grain size, solidification rate and nucleation time

Abstract

ABSTRACT. The influence of titanium and zirconium microadditions on the grain refinement in aluminum weld metal was investigated. These grain refiners significantly altered the morphology of the solidification structure. The time to nucleate the first grain in the weld metal, the weld metal solidification rate and the columnar grain size were all characterized as a function of the grain refiner content. Increasing the zirconium and titanium contents altered the weld pool shape, which increased the solidification rates, increased the nucleation rate and promoted grain refinement. A grain refinement model based on heterogeneous nucleation on second-phase particles is introduced