The durability of steel grinding balls is determined not only by their hardness, but also by the quality of the steel macro and micro structure. The structure of the steel from which steel grinding balls are made is studied using the fracture method. This method consists in determining the steel structure by looking at its fracturing or a specially prepared surface (in the case of Energosteel -templets). This gives an idea of the general structure of the metal and the presence of defects therein.
We would like to draw your attention to the fact that this method differs from fractography, because it does not apply magnifying instruments. Fracture method can be attributed to the first stage of fractographic analysis – visual examination. Fractography aims at determining the causes of the balls fracture, while fracture method used in our plant aims at improving the grinding balls quality, thus preventing splits during the use of grinding balls.
What is a fractis? The fractis is the surface of the sample split when it breaks. In order to get the split of the steel grinding ball, the «Energosteel» plant uses an impact drop machine. But the destruction of our grinding balls is not so easy, since our production is aimed to the increased impact resistance of grinding balls, which guarantees high operational properties of steel grinding balls and the absence of destruction (splitting).The split is prepared from a hardened grinding ball that has not passed its self-tempered. This ball is easily destroyed.
The resulting split makes it possible to visually determine the hardenability depth (martensite). This is very convenient, especially on large-diameter balls, where it takes several days to made templetes for measuring hardness. This method has a slight error, as the martensitic layer depth decreases after self-tempered. In any case, this method occurs because, in a short period, it makes it possible to adjust technological production regimes and to obtain products of the high quality.