Flame hardening

It is the simplest method used for heat treatment since ancient times. Sometimes the whole part, sometimes a part of it, is removed to the austenite field by flame and then cooled in a suitable environment.

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Today, it has different application areas, from gears that are too large to fit in ovens to hardening a part that is urgently needed in the workshop.

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Although a precise depth cannot be achieved when used as surface hardening, depths of 7-8 mm can be reached.

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The flame can be produced by acetylene, propane or natural gas. The same flame source can be adjusted and used for both the hardening and tempering phases.

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Since it is carried out in an open air environment and oxygen is needed for flame formation, it is possible to see decarburization in the parts. For this reason, it is not very suitable for high alloy materials.

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For efficient hardening to occur, there should be around 0.40-0.50% carbon in the material. If these types of materials are cooled quickly, they gain a hardness of around 60 HRC.

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