Thermal treatment of nitriding: characteristics and applications

febbraio 14, 2023

Nitriding is a heat treatment that is performed on some types of steel to improve their resistance to fatigue and wear. Today, we will explore the specific characteristics of nitriding, the reference standard and its main applications.

What is nitriding and what is it for?

Nitriding is a heat treatment that is performed on steels to increase their surface hardness, improving their resistance to fatigue and wear. It occurs at lower temperatures than case hardening, which makes it very suitable in gear construction to limit deformation during the heat treatment process.

Increase the surface hardness of the steel, improving its resistance to fatigue and wear. This is achieved through the addition of nitrides, which give the material greater mechanical resistance.

Peculiar characteristics of nitriding

Nitriding is a heat treatment that can reach typical depths of up to 0.6-0.7 mm with surface hardness even up to 600-650 Hv1. There are 3 different types of hardening thicknesses: the total nitriding thickness, which represents the distance between the external surface and the point beyond which the hardness remains the same as it is at the heart, the effective nitriding thickness, which is the distance from the surface to the point where there is a hardness of 100 Hv more than that at the heart (hence the hardness not changed by the heat treatment), and the thickness of the white blanket, which is the outermost layer of the piece, usually often a few µ.

Applications and reference standard of nitriding

Nitriding is a heat treatment widely used in the world of gears, where surface hardness and wear resistance are particularly important. We often use it in shafts, bushings and pinions, where we try to limit heat treatment deformations.

The reference standard used for the nitriding treatment is UNI EN 5478. This establishes the technical specifications for the nitriding of ferrous metals and defines the minimum requirements for the treatment process. Its compliance guarantees the effectiveness and quality of the nitriding heat treatment.

Efficacy of nitriding

In conclusion, nitriding is an effective heat treatment to increase the surface hardness of some types of steel, improving wear resistance and fatigue resistance. Thanks to its particular characteristics, such as the low processing temperature, it is very suitable for the construction of gears and machine parts that require high resistance to wear and fatigue. Ensuring compliance with the UNI EN 5478 reference standard is essential to ensure the effectiveness and quality of the nitriding process.

Thermal treatment of nitriding: characteristics and applications

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