Coherency and Grain Size Effects on Solidification Crack Growth in Aluminum Welds

Abstract

A mass-balance model has been evaluated that estimates the critical conditions for sustaining continuous crack growth in the weld mushy zone. With the aid of a strain partition model, the critical local strain rate (across the weld) has been related to the critical grain boundary deformation rate needed for crack growth. In the present work, these two models are applied to aluminum welds to investigate the theoretical effects of several metallurgical factors on solidification cracking susceptibility. Calculations quantify the improved cracking resistance associated with a smaller coherent temperature range, grain refinement, high solid fraction at coherency, and rapid development of strength.