A permanent magnet stirrer was built to study the effect of different magnetic field stirring modes on the solidification quality of Sn-20 wt-% Pb alloy ingots. The internal quality of the ingot can be improved by adjusting both the stirring speed and the modes. When the continuous magnetic stirring mode was adopted, the higher the stirring speed, the higher the flutter height at the ingot edge. When the stirring speed was 200 rpm, the flutter height reached 4.12 mm. The rotating magnetic field can significantly refine the grain size of the ingot. When the stirring speed of the magnetic field was increased from 0 rpm to 200 rpm, the grain size of the ingot reduced from 301 μm to 241 μm. By fixing the magnetic field stirring speed to 200 rpm and adjusting the mode to the alternate stirring process, the flutter height at the ingot edge reduced to 1.86 mm, which stabilized the liquid level of the molten alloy in the crucible. In addition, the grain size of the ingot was shortened to 223 μm, and the elemental homogeneity within the ingot was optimized.
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