A quantitative hot tearing criterion for aluminum alloys

Abstract

In this study, a new hot tearing criterion was proposed to quantitatively predict open and segregated hot tears in aluminum alloys. In the suggested model, the displacement of grains at a grain boundary near the solidus temperature was considered as the main reason for crack formation. In this model, it is assumed that when the distance between two neighbor grains exceeds the distance between those grains at the coherency temperature, the enriched liquid can penetrate to the root of the dendrites and form segregated and open hot tears. The main parameters of the model are microstructure (grain size and number of grain boundaries), critical strain, applied strain, and width of generated cracks. The index was verified by the solidifying shell tensile (SST) test of an Al alloy containing 0.95 wt% Cu and 0.12 wt% Fe. Also, the critical strain for crack formation in the test was calculated by using accumulated strain theory and load-time curves. The results revealed that the proposed model can suitably predict the number of open and segregated hot tears generated in the SST test samples.