Ductile iron castings are used as shaft parts, such as crankshafts and connecting rods of diesel engines, with high mechanical strength and high mechanical resistance, and quenching and tempering of cast iron parts. The ductile iron castings are heated to a temperature of 860-900 ° C to keep the matrix austenitized, and then quenched by cooling in oil or molten salt, and then tempered at a high temperature of 500-600 ° C to obtain a tempered sorbite arrangement. The original spherical graphite shape is unchanged. After treatment, the resistance is excellently matched and adapted to the working conditions of the shaft parts.
Ductile iron castings, as a bearing with higher hardness, often quench the cast iron parts and temper at low temperatures. The technology is: the casting is heated to a temperature of 860-900 ° C, the original substrate is austenitized and then quenched in oil or molten salt, and then heated and tempered at 250-350 ° C, the original matrix is converted back to The fire martensite and the retained austenite arrangement have the same shape of the original spheroidal graphite. The treated casting has high hardness and certain tolerance, retaining the smooth function of graphite and improving the wear resistance.
As a kind of highly cast iron material, ductile iron castings have close comprehensive performance to steel. It is based on its excellent performance and has been successfully used to cast some parts with high requirements, high degree of toughness and wear resistance. Ductile iron castings have rapidly developed into cast iron materials that are second only to gray cast iron and are widely used.