Premium
Prediction of Shrinkage Microporosity in Gravity‐Cast and Low‐Pressure Sand‐Cast Mg–6Gd–3Y–0.5Zr Magnesium Alloys
Author(s) -
Zhou Bo,
Wu Di,
Chen Rongshi,
Han En-Hou
Publication year - 2019
Publication title -
advanced engineering materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 114
eISSN - 1527-2648
pISSN - 1438-1656
DOI - 10.1002/adem.201900755
Subject(s) - shrinkage , materials science , dimensionless quantity , casting , volume fraction , volume (thermodynamics) , magnesium , composite material , ultimate tensile strength , mass fraction , metallurgy , thermodynamics , physics
The Niyama criterion and the dimensionless Niyama criterion are used to predict shrinkage microporosity in Mg–6Gd–3Y–0.5Zr magnesium plates processed by gravity casting and low‐pressure sand casting. Instead of the Niyama evaluation condition recommended by commercial ProCAST software and precious studies, the most appropriate Niyama evaluation condition is suggested as fraction solid of 0.7 for the investigated alloys. With consideration of the actual distribution of shrinkage microporosity and the definition of unsound samples (shrinkage microporosity volume fraction is higher than 1% based on the tensile test), the corresponding threshold Niyama values are qualitatively determined as 0.44 and 0.3 °C 0.5 s 0.5 mm −1 for gravity‐cast and low‐pressure sand‐cast plates, respectively. It indicates that exerting pressure contributes to the decrease in the threshold Niyama value. In addition, exerting pressure can reduce the amount of shrinkage microporosity. For the dimensionless Niyama criterion, it is capable to quantitatively predict the shrinkage microporosity volume fraction in low microporosity‐containing regions, but not in high microporosity‐containing regions.