Case Hardening Steels It is used in the manufacture of parts such as gears, shafts, piston pins, sprockets and rollers, discs, guide bearings, rolling bearings, rollers, some measurement and control tools, cutting tools. Case Hardening Steels 15NiCr131.5752 Case Hardening Steels 16MnCr51.7131 Case Hardening Steels 16MnCrS51.7139 Case Hardening Steels 17CrNi6-61.5918 Case Hardening Steels 17NiCrMo6-41.6566 Case Hardening Steels 18CrMo41.7243 Case Hardening Steels 18CrNiMo7-61.6587 Case Hardening Steels 20MnCr51.7147