Annealing heat treatment of ductile iron gearbox casting

- May 16, 2019-

In the process of using the ductile iron gearbox casting, its comprehensive performance is close to that of steel. In operation, it has developed a cast iron material which is second only to gray cast iron and widely used. Gearbox ductile iron castings are widely used in the mechanical manufacturing industry due to their excellent performance and can sometimes be used in place of cast steel and forged steel.


The annealing heat treatment of the gear box ductile iron parts is to improve the overall performance of the cast iron parts. Common processes include annealing, normalizing, quenching, and the like. Ductile castings require higher hardness as bearings, and the cast iron parts are often quenched and tempered at low temperatures. The specific method is to heat the casting to a temperature of 860-900 ° C, heat the original matrix to austenitize and then quench in oil or molten salt to achieve quenching, then heat and temper at 250-350 ° C, the original matrix is converted into The tempered martensite and the retained austenite structure have the same shape of the original spheroidal graphite.


The castings processed by the gearbox ductile iron castings have high hardness and certain toughness, retaining the lubricating properties of the graphite and improving the wear resistance. Ductile iron parts are used as shaft parts, such as crankshafts and connecting rods of diesel engines, which require high-strength mechanical properties with high toughness and good toughness. The tempered sorbite structure is obtained, and the shape of the original spheroidal graphite is unchanged. After treatment, the strength and toughness are well matched, and it is suitable for the working conditions of the shaft parts.