3. Heat treatment

3.1 Implementation

Steels used for mechanical applications are rarely used in their equilibrium state. Their properties are modified by heat treatment, either before the steel is delivered – or in its "pretreated" state –, or after rough machining and before finishing. Using "pretreated" steels is advantageous: the manufacturing range does not include heat treatment, which risks deforming the parts and requires reworking for precise parts. The mechanical properties of "pretreated" steels are limited by the need to be able to machine the steel: the order of magnitude for easy machining is 35 HRC, which corresponds to a strength value of $R_m$...