What Are The Solidification Methods Of Castings?

There are three main solidification modes for castings: layer-by-layer solidification, intermediate solidification, and volume solidification (paste solidification). ‌‌

‌Layer-by-layer solidification‌: In this solidification mode, the solid phase and liquid phase on the cross section of the casting are separated by a clear boundary. Common in pure metals and eutectic alloys, such as gray cast iron, low carbon steel, industrial pure copper, industrial pure aluminum, eutectic aluminum silicon alloys and some brasses. The alloys solidified layer by layer have strong filling capacity, which is convenient for preventing shrinkage cavities and shrinkage. The internal structure of the casting is dense and of high quality.

‌Intermediate solidification‌: When the crystallization temperature range of the alloy is wide, but the temperature gradient of the casting cross section is large, the width of the solidification zone is between layer-by-layer solidification and volume solidification. Common in medium carbon steel, high manganese steel, white cast iron, etc. The intermediate solidification castings are between layer-by-layer solidification and volume solidification in terms of shrinkage compensation, hot cracking tendency and fluidity.

Volume solidification (paste solidification): In this way, the solidification zone where liquid and solid coexist is very wide, even running through the entire cross-section of the casting. Common in ductile iron, high carbon steel, tin bronze and some brasses. The alloy with volume solidification has poor filling capacity, loose internal structure, poor casting quality, and it is difficult to obtain a crystallized and solid casting.