... : <=0.050% 3.grade: G4 Low carbon steel ball is magnetic, it must be plated when it is out of surface,it ... can be plated with zinc,glod,nickle,chrome and so on.The frictional ... frictional resistance and hardness is worse than bearing steel ball(the HRC of GCR15 steel ball is 60-66).Detailed Product Description ... more ,please be free to contact us Small Low Carbon Steel Balls