Why are blue finishes more durable tha CC?

[Craig Budgeon]

Casehardening is not a plating, instead you are adding carbon to the the surface of the part chemically by the aid of heat ( 1375-1450F) and time. Hardening takes place when the part is quenched. Quenching solutions vary widely and are still secret when people are trying to achieve colors too. The depth of case hardening can vary from>0003" (speedcase) to as much as .030" (carburize). The purpose of cashardening is to maintain strength with a soft core and wear resistance with a hard surface. Case color provides no benefit but eye appeal to the part. An addendum to bluing: If you have a welded part and you rust blue it the weld will not show, if you chose to nitre blue it, hot blue it, or oxide it then the weld will show.