Case-hardening steel

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Among the hardening steels include carbon and low alloy steels . They have a carbon content of 0.10% to 0.20%. Since case- hardening steels have too little carbon to produce significant increases in strength during martensitic hardening , they are "used" in a carbon-containing atmosphere ( case hardening ) and heated to temperatures between 880 ° C and 1050 ° C ("annealed"). The carbonaceous agent is in a solid , liquid or gaseous state of aggregation added. At the high temperatures , the carbon diffuses from the outside into the surface layer of the steel (depending on the carburizing agent 0.1-0.3 mm per hour , strongly dependent on the temperature) and increases the carbon content of the surface layer to around 0.8%, see above that the hardening on the surface of the component is more effective than inside. The result is a component that has a high level of toughness on the inside and a considerably greater hardness on the surface and thus a high level of resistance to wear .

Case-hardening steel is used for gear wheels , shafts and bolts, among other things .

Machinability

See machinability of steel .

Examples of case-hardening steels

  • C15E: mild steel 0.15% C; soft annealed (only recognizable by the outdated standard designation "Ck 15 G"); unalloyed
  • 20MnCr5 (EC100)
  • 17CrNiMo6
  • 16MnCr5 (European standard: EC80)
  • 15CrNi6
  • C10 unalloyed case-hardening steel with 0.1% carbon

literature

  • DIN EN 10084 Case hardening steels - Technical delivery conditions; German version EN 10084: 2008 , June 2008.