spheroidal ink casting

(1) Chemical composition is strictly required, and the content of carbon and silicon required for the original iron solution is higher than that of gray iron, so as to reduce the content of manganese, phosphorus and sulfur in ductile iron.

(2) The temperature of molten iron is higher than that of gray casting, and is higher than that of compensated spheroidization.

(3) Spheroidization, that is, adding spheroidizing agent to iron solution.

(4) Inoculation treatment.

(5) Less fluidity and larger shrinkage of spheroidal ink castings require higher casting temperature and larger size of casting system. The principle of sequential solidification is adopted in most cases, such as riser and cold iron.

(6) Heat treatment

As bearings, ductile iron castings require higher hardness and are often quenched and tempered at low temperature.Process are: all kinds of casting temperature, heated to 860-900 ?? heat preservation to the original matrix all austenitizing after cooling achieve quenching in oil or molten salt, after 250-350 ?? heat insulation tempering, the original matrix into tempered martensite and retained austenite, the original spheroidal graphite morphology is constant.