Effect of pouring and mold temperatures on hot tearing susceptibility of AZ91D and Mg–3Nd–0.2Zn–Zr Mg alloys

Abstract

Pouring and mold temperatures are two important parameters during casting magnesium components. The present study examined their influence on hot tearing susceptibility (HTS) of commercial AZ91D and newly developed Mg–3Nd–0.2Zn–Zr (mass fraction, %; NZ30K) magnesium alloys in gravity permanent mold casting condition. The results indicate that mold temperature shows much more significant influence on the HTS of both alloys than pouring temperature whose influence only can be distinguished at low mold temperature (341 K for AZ91D alloy and 423 K for NZ30K alloy). Hot tearing susceptibility prediction model concerning feeding parameters, grain size and solidification range, is more suitable to estimate the HTS of different magnesium alloys than the model only concerning feeding parameters. In order to achieve better hot tearing resistance, the ranges of pouring and mold temperatures are suggested to be 961–991 K and ≥641 K for AZ91D alloy, 1003–1033 K and ≥623 K for NZ30K alloy, respectively.