Quenching consist of heating the steel above the critical point( austenite temperature) and holding at that temperature for enough time to change the crystalline structure. Following this operation, the steel rapidly coolied and obtained. martensitic microstructure. After this process steel is very brittle and fragile structure in order to achieve the desired hardness and toughness values of tempering (tempering) process is applied. This process is at least 2 times steels, cold work, hot work steels, should be at least 3 times.

Hardening process in vacuum furnaces, heating under inert atmosphere at room temperature is done in a balanced way of a heat treatment process allows a very homogeneous. Materials under high pressure in a balanced way austenite rapidly cooled from the temperature. The vacuum furnace can also apply isothermal waiting for different dimensions which allows cooling in marquenching technique for these tools.

The most important advantages of the vacuum furnace heat treatment are as follows:

• End of the hardening process is obtained brilliant surface
• With heating and cooling a homogeneous, low distortion,
• Keeping records of computer-controlled heat treatment process management and history,
• Does not create pollution in the environment,
• Constantly checking the temperature with thermocouples placed in the core,