What is the difference between case hardening and hardening?
Mild steel cannot normally be hardened due to its low carbon content. In order to increase the hardness of mild steel to improve wear characteristics the process used increases the carbon content of the treated surface. The part being treated is either locally or completely covered with a high carbon compound which will give up some carbon when subjected to heat. This free carbon will then be absorbed by the surface of the steel to increase its carbon content and allow it to be hardened. This thin layer of high carbon steel encases the low carbon steel core, hardening this encasement is called case hardening. It has the advantage of using easy to machine and relatively low cost material to create a part with high local hardness where required. High carbon steels can be through hardened by heating beyond their transition temperature ( where the steel crystal structure changes) and then cooling rapidly to keep the crystal structure from the high temperature state. The problem with this i
