Prediction of Shrinkage Microporosity in Gravity‐Cast and Low‐Pressure Sand‐Cast Mg–6Gd–3Y–0.5Zr Magnesium Alloys

Abstract

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 °C0.5 s0.5 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.

Evaluasi Efisensi Riser Untuk Bentuk Riser Samping yang Berbeda Menggunakan Metode Simulasi Casting

“…Selain simulasi langsung, berbagai kriteria digunakan untuk memperkirakan pembentukan shrinkage berdasarkan parameter termofisika dari proses solidifikikasi [14]. Salah satu kriteria yang sering digunakan adalah Niyama kriteria [14]- [16]. Niyama kriteria adalah kriteria paling penting untuk prediksi porositas akibat shrinkage [15].…”

Study on the evolution of the microstructure, phase composition, three‐dimensional morphology, and hardness in the solution treatment of Mg−7.80Gd−2.43Y−0.38Zr alloy

“…Therefore, a deep understanding of the phase behaviour of the Mg−Gd−Y−Zr alloys under different solution treatment conditions will provide useful guidance for optimizing the heat treatment. Currently, there have been many studies on as‐cast and T6‐treated Mg−Gd−Y−Zr alloys under various conditions [16–24]. However, there have been few comprehensive studies on the solution treatment of Mg−Gd−Y−Zr alloys.…”