... Element Cold-rolling roller and roller blankworking roller 210-665mm middle roller 300-700mm backup roller 400-750mm smoothing roller 400-8509Cr2,9Cr2Mo, ... ≤3 Genter porosity≤3 Segregation≤3 Hot-rolling roller and roller blank 400-850mm 45Cr,55Cr,42CrMo,50CrMo, 60CrMo ... ≤0.25 Crack,shrinkage, flake and bubble without visualization Continous casting roller and roller blank180-500mm Hz102f R73 BCR01 20 ...