1, the principle of forming steel ball hardness is different. Hot-rolled ball is through the unique quenching process to make the hot state steel ball rapid cooling, prompting the metal microstructure of austenite turn quickly into martensite organization with considerable wear-resistant hardness, so it is through the quenching of hardness, its hardness can reach 63 ~ 65HRC. Casting ball is mainly dependent on the addition of a certain amount of alloying elements chromium (Cr) to make steel balls produce a certain degree of hardness and wear resistance, the higher the content of Cr The higher the Cr content, the better the hardness and wear resistance of the ball, but the higher the cost of the steel ball; domestic high chromium ball containing Cr is generally 8-12%, hardness of 55-59HRC; the newly introduced a high alloy cast ball containing Cr up to 18%, but also add a small amount of tungsten (W) and molybdenum (Mo) and other rare metals, hardness of 60-62HRC, wear resistance is better, but the production cost is higher, the ton sales price Reach 14000 yuan or more.
2, density size is different.
Hot-rolled balls due to the use of square steel billet hot-rolled extrusion production of round steel as raw materials, while the production process of hot-rolled balls and through the roll forming extrusion, so the density of hot-rolled balls are generally greater than 7.85g/cm3 or more.
Casting ball due to the traditional sand casting process, so the internal and surface of the steel ball will inevitably produce porosity and sand trapping, there are also casting waste edge, so the density is generally below 7.75g/cm3.