Flame hardening steel involves heating the steel part and then cooling it. The first step of the process changes the molecular structure of the steel and makes it hard, but brittle. If dropped or struck hard, it could actually shatter. The second part of the process, known as annealing, involves reheating the steel and re-cooling it. Once this second part of the process is complete, the steel is hardened and yet malleable enough that it can still be worked.
The Flame Hardening Process
- The steel part is heated until it glows red-hot. As the part is heated it goes through several different color changes until it passes blue-hot and finally becomes red-hot
- The red-hot steel part is then immediatly submerged into a vat of room-temperature water, which is called quenching. At this stage the part will be hard and extremely brittle
- The part is then reheated and when it’s blue-hot it is once again submerged into the vat of water. The part is now fully hardened.
For more information see DIECUT’s Flame Hardening Services
This video shows an example of the Flame Hardening process
references: ehow, youtube, wikipedia