New Type grindig Balls -CADI Grinding balls

1. Origin of ADI

Austempered ductile iron is a kind of material with high strength, plasticity, toughness and hardness. Because the materials used are mainly silicon and manganese, Its production cost is relatively low, and it is a kind of wear-resistant material with market competitiveness. Because of its excellent comprehensive mechanical properties, ADI  has been regarded as one of the important achievements in iron metallurgy in recent 30 years and has been widely used in various industrial sectors. For austenite + bainite matrix was the shell body of the ductile iron (ADI), the United States have research results in the 1950 s, but it was not until the 70 s application in the industry, our country in the 80 s by the tsinghua university professor de-hai wu research the shell body nodular cast iron and application in the industry, but because of the technology and equipment conditions not widely promoted.

There are still some problems of technical control during the mass production. such as molten iron casting time control,  isothermal quenching  or continuous quenching equipment, cooling medium, quenching temperature and cooling speed etc, if it is not strict control of each links of  professional manufacturers, easy to cause unstable performance , waste products. Therefore, there are not many Chinese domestic manufacturers with production conditions, which have not been widely popularized. Now the market is mainly composed of chrome steel balls and forged steel balls.

In the past 20 years , the casting output of industrial developed countries has been declining continuously, accounting for 70% to 80% of the casting output. Only ductile iron casting output has been increasing. In ADI bainite, retained austenite matrix contains any number of free carbide ADI, called CADI, carbide role is mainly to improve the hardness of ADI, increase the wear resistance of materials, anti-wear performance of high alloy wear-resistant cast iron, and plastic toughness is better than high alloy wear-resistant cast iron, very suitable for mining and other anti-wear performance requirements of the parts.

 2. Characteristics and advantages of  (ADI)

（1）High hardness and good wear resistance

Except the spheroidal graphite distributed uniformly in the microstructure of ADI steel ball, the matrix is the bainite + residual austenite containing a certain amount of carbide. The existence of residual austenite makes the grinding ball form a high hardening layer on the surface through impact and friction during use. With the constant wear of the grinding ball, the high hardness layer on its surface will be generated continuously and automatically, thus greatly improving the wear resistance of the grinding ball.

（2） Hard outside and tough inside, not broken

While ADI steel ball has high hardness, its impact toughness is generally ak= 12-21j /cm2. According to the current national standard, the surface hardness of Chrome  grinding ball is HRC45~HRC58, but its impact toughness is only ak=2.5~3J/cm2. Although the impact value of forged grinding ball (ak=12J/cm2) is close to that of ADI ball, its surface hardness is HRC56~60 degrees, and its inner hardness is HRC40~56 degrees, but its price is high, its price is unstable, its material and material are mixed, and its service cost is relatively high. Therefore, the perfect combination of hardness and toughness makes ADI  steel ball truly reach the external hard and internal toughness, and reduces the direct and indirect economic loss caused by the crushing factor of grinding ball for users.

（3）   Regular appearance and increased production

The ADI steel ball produced by our factory is formed on the automatic production line of iron mould sand overlaying, and heat treatment is carried out through the computerized automatic heat treatment system. The production process of each stage is stable, which ensures that the shape of the grinding ball is regular (the same as that of the forging ball). In the process of using, these grinding balls always keep a good shape and do not lose roundness, so as to improve the production of the mill stand.

（4）  Light weight and obvious energy saving effect

  ADI BALLS

ADI ball is ductile iron, in which there is a lot of spheroidal graphite. Graphite is a non-metallic element, so the proportion of this kind of ADI grinding ball is 8% lighter than that of ordinary low chromium grinding ball, high chromium grinding ball and forged grinding ball (the density of ADI  grinding ball is 7.3t/m3, the density of low chromium grinding ball, high chromium grinding ball and forged grinding ball is 7.7t/m3). The load of the mill is reduced, so start and running load of ball mill is less, can save energy above 10% , at the same time also make equipment related parts wear loss, reduce the noise in the process of ball mill operation, at the same time, ADI  ball without polluting  chromium element, not pollution of ores and recycling water, achieve the goal of the environmental protection.

Review, the steel ball (ADI) life is ordinary low chromium grinding balls with the operating conditions of 2-3 times,  is 1-1.5 times of high chrome casting balls and forging balls ,save grinding mechanical and electrical consumption of 10-15%, increase the output capacity more than 5%, reduce 5 db noise, impact toughness ak = 12-21 j/cm2, is an ideal grinding balls for large ball mill and  SAG in the future.

3.  ADI grinding balls comparing with Forged Grinding balls