... quality control system, various types of machining, forging, heat treatment, physical and chemical testing equipment.we produce work roll,back up roll,straightening ... , finished roll,casting,forging,oil drilling tools,etc . back-up rollDiameter:240-900Material:70Cr3MoR,9cR2mOr,86CrMoV7,MC3 Note:GB/T13314-91 GB/T15547-1995