Harvey process

A process for hardening the face of steel, involving the additional carburizing of the face of a piece of low-carbon steel by heaping a solid carbon-rich fuel (such as charcoal) on the face of the steel and then subjecting this to very high heat at high pressure for a prolonged period of time, followed by a violent chilling, as by a spray of cold water. This results in a thick surface of extreme hardness supported by material gradually decreasing in hardness to the unaltered soft steel at the back.