Effect of solid fraction, grain misorientation and grain boundary energy on solidification cracking in weld of Al–Cu aluminum alloys

Abstract

Solidification cracking is one the most common types of cracking in the weld of the aluminum alloys. Although some numerical models have been developed for investigation of the solidification cracking, the effect of the grain misorientation on the solidification cracking susceptibility (SCS) of a weld has rarely been considered. This work studies the effect of the angle between the primary arms of the dendrites on the SCS. Hence, a solidification cracking model was developed given the grain misorientation in the convergence condition. The model was investigated for Al–Cu alloys. When the grain boundary energy was considered in the model, there was an increase in the SCS for misorientation angle between 7° and 22°. However, for misorientation angle less than 7° and more than 22°, there was a slight decrease in the SCS with enhancement of the misorientation angle. The SCS was also influenced by the solid fraction range in which the model was evaluated. As the solid fraction changed from fs = 0–0.98 to fs = 0.87–0.94 (brittle temperature range), the peak of the SCS curve shifted from Al-1.5Cu to Al-3.5Cu. The latter composition is in agreement with the experimental results in the literature.