Middle Carbon ball, Material:55SiMov, Used for oil Drilling tools and ore drilling tools 55 SiMoVA(AISI S2) ball , this product mainly used ... ; and drill bits parts,stamping parts, plastic parts, turning parts, casting and forging parts. bolts and nuts ,non-standard parts , stainless ... :86-574-88473666 AISI UNS T41902 steel Ball for drilling tools