Steel Grind Ball: high hardness, no breakages, good wear resiscance, even wearing Steel Grinding Ball Forged Steel Grind Balls:1) Diameters: dia. 20mm - dia. 150mm2) Hardness: HRC50-633) Chemical elements: C: 0.52-0.65, Si: 0.15-0.37, Mn: 0.6-1.2, P: 0.04 max., S: 0.04 max.4) Cr: 0.25 max.RCAB-I forged grinding balls:1) Diameters: dia. 40 - dia. 150mm2) Hardness: HRC58-653) Chemical elements: C: ...