... ) Noxious Element Noxious Element Cold-rolling roller and roller blankworking roller 210-665mm middle roller 300-700mm backup roller 400-750mm smoothing roller 400-8509Cr2,9Cr2Mo,9Cr2W ... General porosity ≤3 Genter porosity≤3 Segregation≤3 Hot-rolling roller and roller blank 400-850mm 45Cr,55Cr,42CrMo,50CrMo, 60CrMo,60CrNiMo,H13 ...