... :2.0-2.8,si:<1.0,mn:0.5-1.5,cr:22-30,mo:0-1.0,cu:0-2.0 ... .10,s<0.06middle chrome casting steel ball:c:2.1-3.2,si:0.5-2.2,mn:0.5 ... -1.5,cr:7-15,mo:0-1.0,cu:0-0.8,ni:0 ... -1.5,p:<0.10,s<0.06low chrome ... casting steel ball:c:2.2-3.6,si:<1.2,mn ... :0.5-1.5,cr:1.5-3.0,mo:0-1.0,cu:0-0 ...