DEVELOPMENT AND APPLICATION OF CR25 HIGH CHROMIUM CAST IRON GRINDING BALL (3)

(4) Properties of cr25 high chromium cast iron ball grinding products

Metallographic structure: The metallographic structure of CR25 high chromium cast iron grinding ball is tempering, eutectic carbide (Ke) and primary carbon, carbide (K1) are homogeneously embedded in the matrix of fire Martensitic (m), and the particles, grains, second and Secondary Carbides (K2) are uniformly distributed, there is also a small amount of residual austenite (A,).

Hardness: HRC63 -68, central hardness, surface hardness difference < HRC3.

Corrosion resistance and wear resistance: the 25% CR content ensures the corrosion resistance of the grinding ball, the performance is in the second mutation point of the n/8 law, the actual use effect is ideal, and the content of the matrix, medium carbide, is about 5% higher than that of the CRL5 casting ball, the hardness of the carbide is also increased, which makes the grinding ball more wear-resistant

3.Client using situation

Yangquan II power plant has coal mills, four, model d-100. Ball load 62.7 tset.

Ball loading operation time: October 28, 1996- March 7, 1997, the average operation of each mill 554 hours, a total of 92,000 tons of coal production, the average output of 41.5 tons per hour. In the running period, the four grinding machines have not made up the ball. But before uses the forging ball every day, each mill must fill the ball about 600g; its attrition is 210g/t coal.

According to the usage, the grinding ball of CR25 high chromium cast iron is calculated according to the hardest grindable system, its wear is about 60g/t coal, and no broken ball is found.

4.Conclusion

(1) Cr25 high chromium cast iron grinding ball has the hardness of hrc63 ~ (68), low wear, small breakage, no ball, no loss, round phenomenon, and strong anti-corrosion ability. It is a new type of product of high quality, suitable for wet process production and mine grinding and coal grinding

(2) Some professional wear-resistant material factories, such as Ningguo wear-resistant Material Factory, have also begun to study further the high chromium cast iron grinding ball with high chromium content developing to the diversification direction of Taijin. A new type of high chromium cast iron containing 23%-28% CR and W and B has also been studied in this plant and has achieved initial success. Its chemical composition is: c 2.4%-3.0% , SI ≤1% , MN 0’6%-10% , CR 23%-28% , b 0.05%-0.16% , w 0.8%-2% , p ≤0.1% , s ≤0.06% .

The series of high chromium cast iron products will be the next step of grinding ball research and development of important development direction.

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