Experimental and numerical analysis of grain refinement effect on hot tearing susceptibility for Al–Mg alloys

Results of finite element method (FEM) thermal stress analyses during solidification of an Al–Mg alloy with different grain sizes revealed the contribution of the macroscopic strain to the reduction of hot tearing susceptibility by the grain refinement. This study used an elasto-creep model to describe the mechanical behavior of the alloy in the semi-solid state. The grain size–dependence was described using the experimentally determined two parameters of n (=dlogε ̇ ^c /dlogσ) and A in the power-law creep model in earlier work. Results showed that grain refinement makes the creep strain distribution more uniform and suppresses the maximum strain value during solidification, which in turn should contribute to reducing the hot tearing susceptibility. This result demonstrates that the grain size–dependence of the two creep parameters during the solidification is a key factor for the quantitative prediction of hot tearing tendency with the consideration of grain size.