Steels for heat treatment - Standardization

To meet all these requirements, the range of special steels for heat treatments must include grades with different hardening capacities associated with different hardenability and, where applicable, with specific features relating to the conditions of use (shaping, but also particular heat treatments), so that the user can always find the steel enabling him to achieve the level of performance targeted for the part he is making.

This article describes all steels used for heat treatment, whether in bulk, localized or thermochemical treatment, taking into account the specific conditions of use. In fact, the reader will see that, around a common base, steels respond to the particularities of treatment and use conditions.

However, the full range of heat treatment steels is not yet covered by a comprehensive body of European standards. The basic grades are described in general European standards, while certain specific grades (in terms of their application or use) are still defined in national standards which have not been replaced by European standards. For this reason, in the remainder of this presentation, we will distinguish between the two origins, while retaining the classification according to basic standards. For simplicity's sake, we will refer to a French NF EN standard reproducing a European standard as a "European standard", and to an NF A standard whose subject is not yet covered by a European standard as a "French standard".

It should be noted that all these steels that have to undergo one or more heat treatments are classified as special steels.

The complete study of the subject includes the articles :

• M 4 530 – Steels for heat treatment. Properties and selection guide;

• M 4 531 – Steels for heat treatment. Standardization (this article) ;

• M 4 532 – Steels for heat treatment. Processing ;

• Doc. M 4 533 – Steels for heat treatment.