Brief analysis of heat treatment process of chromium alloy casting ball (2)
2.The structure and properties of the treated cast grinding ball were analyzed
After quenching and tempering, the 30mm cast grinding ball’s microstructure is M(back)+(CrFe)7C3 + little residual Austenite. The matrix structure and carbides form Austenite mechanical integral body. The martensite matrix supports the carbides well so that both eutectic and hypereutectic carbides are covered and protruded on the wear loss surface. Not only does the matrix possess high hardness, but it also effectively exerts the anti-abrasive effect of the carbides. The wear resistance of the alloy increases with the increase of the amount of carbonized material, which increases the wear resistance of the cast ball. Besides, the presence of Austenite small amount of residual A is also helpful to improve the impact of toughness.
3.Cast grinding balls industrial test
In order to verify the wear resistance of SR cast ball, the SR cast ball produced by this technique and other square cast grinding ball produced by this technique are selected to conduct a comparative test in the same mill. 280pcs of 90mm cast balls were selected, and two small holes were punched in each ball as marks. 290pcs of 90mm cast balls produced in other ways were selected, and one hole was punched in each ball as marks. Put them in a 3800×13500mm ball mill for a comparative test. The mill’s ball loading capacity is 56t, and the test period is from May 14, 1996, to February 17, 1997. The transportation time is 5537h, and the ore-handling capacity is 371147t. The data of the two balls in the whole test process is shown in the attached table.
It can be seen from the attached table that the grinding rate of SR cast ball is nearly 1 time lower than that of other cast balls produced by other techniques, and the efficiency and benefit of sR cast ball is relatively obvious.
(1) It is the key to improving the high chromium cast grinding ball’s wear resistance that the correct thermal treatment technique can obtain the appropriate substrate organization.
(2) As the cast grinding ball’s size is different, its heat treatment process should be adjusted accordingly.
(3) By increasing the content of CR, it is beneficial to form a large amount of M7C3 type carbides and martensite matrix so as to improve the hardness and wear resistance of the cast ball