Austempered Ductile Iron (ADI) is a new generation of ductile iron material developed in the past four decades, and is known as "high-tech in the field of materials." It is a high value-added casting product based on bainite ferrite and carbon-rich austenite obtained by austempering ductile iron with a certain composition. It has excellent comprehensive mechanical properties:

(1) High strength and high toughness: According to the American ADI standard (ASTMA897/897M-06), the σb of ADI can reach 750~1600Mpa, and the elongation rate can reach more than 11%. Compared with ordinary nodular cast iron, under the same elongation, the σb of ADI is about twice that of ordinary nodular cast iron; and for the same σb, the δ of ADI is more than twice that of ordinary nodular cast iron.

(2) Lightweight The density of ADI is 7.1g/cm3, while the density of steel is 7.8g/cm3. This means that for parts of the same volume, ADI is about 10% lighter than steel parts.

(3) Low noise The graphite balls present in ADI have strong sound-absorbing properties. At the same time, the elastic modulus of ADI (E=1700Mpa) is about 20% lower than that of steel (E=2100Mpa), which has good shock absorption. .

(4) Good wear resistance. There are a large number of graphite balls in ADI, which has a good lubricating effect and can reduce the friction coefficient and operating temperature. At the same time, there is a large amount of retained austenite in the matrix, some of which will be transformed into stable crystal or microcrystalline martensite due to external force, which increases the surface hardness of the material, resulting in a higher life of ADI in the middle and late stages.

(5) Low price and cost Improve the strength of the component, make it tougher, lighter and more wear-resistant, so that the amount of material required for the production of the component can be reduced. Using fewer materials means lower raw material costs for parts. In addition, ADI is a relatively cheap material compared to steel, aluminum, magnesium and other materials.

Carbdic austempered ductile iron with carbides (Carbdic austempered ductile iron, referred to as CADI), is based on ADI by adding a part of carbide forming elements, such as chromium, etc., to obtain a part of carbides, making it with high toughness at the same time It also has high abrasion resistance.