Melting Method for Reducing Shrinkage Defect of Heavy Wall Ductile Iron Parts
Updated：2018-12-14
Furan resin sand is generally used as moulding material for large ductile iron castings produced in our country. It has a large amount of casting attention and complex structure. It requires a high quality and performance of castings. Some casting defects, especially shrinkage defects, often occur in the melting process, will lead to casting scrap, resulting in significant economic losses, especially for QT400-18AR material, which has high strength and high elongation. There are also shock value requirements. It is not easy for such heavy parts to avoid graphite floating and shrinkage defects while guaranteeing the mechanical properties of products.
The effects of chemical composition and pouring temperature on graphite floatation and shrinkage of 180 mm solid sample were studied by designing small sample experiment and using Eckens analytical equipment. Then it is applied to the production of thick-walled ductile iron castings, and good quality castings are obtained.
Firstly, 500 kg iron was produced to tundish, 1.3-1.5% high magnesium nodulizer, 0.3-0.4% inoculant and 0.8% covering agent were embedded in the nodulizing ladle, and the inner surface of the ladle was spheroidized. After the spheroidizing treatment was completed, the flow inoculant was poured into the inner surface of the ladle, and the samples were analyzed and detected by EPIC instrument.
1.2% Eken spheroidizing agent, 0.8-1.0% covering agent and 0.4% glass crushing were embedded in the spheroidizing ladle. Iron was directly discharged into the spheroidizing ladle and 0.5% Eken inoculant was injected. After the spheroidization was completed, the Ecken inoculant sprayed on the surface was sampled and analyzed by EPIC instrument.
1.2% Eken spheroidizing agent, 0.8-1.0% covering agent and 0.4% glass crushing were embedded in the spheroidizing ladle. Iron was directly discharged into the spheroidizing ladle and 0.5% Eken inoculant was injected. After the spheroidization was completed, the Ecken inoculant sprayed on the surface was sampled and analyzed by EPIC instrument.
