Hardening of Metals: 4 Methods | Metallurgy
The most extensively used method is conventional hardening for quenching in a single medium. The disadvantage of this method, however, is that the cooling rate in the martensitic transformation range will be very high. It will differ only slightly from the rate on the upper zone of super-cooled austenite of low stability and, therefore, cracks, distortion and other defects may [...]