Home Ion nitriding

Heat treatment and ion nitriding

Objective: Resistance to fatigue, wear and seizure

Nitriding is a thermochemical treatment involving the diffusion of atomic nitrogen N onto the surface of steel parts previously hardened and tempered. 

The insertion of nitrogen N into the steel (or N and C for nitrocarburizing treatment) and the formation of nitrides with the steel's alloying elements cause surface hardening. This transformation results in a high-quality nitrided layer, offering a hardness of between 750 and 1100 HV, particularly suited to industrial applications where fatigue and wear resistance are crucial.

Ion nitriding, in particular, uses a process where nitrogen ions are accelerated and bombard the metal surface in a vacuum or gaseous environment, carried out at a controlled treatment temperature. This process achieves greater diffusion layer uniformity through improved ion etching and optimized layer thickness for each specific application. Advantages include a significant improvement in the mechanical strength and durability of treated parts, making this technique particularly popular in most mechanical engineering sectors.

This technology is particularly well-suited when process savings are required.

The ion nitriding process at Thermi Lyon

Ion nitriding is carried out in a vacuum furnace using a controlled flow of active gases, dissociated by plasma.

Vacuuming the oven chamber

Beforehand, the parts are carefully washed in dedicated machines. Ion nitriding is carried out in a vacuum furnace in an air-free environment to avoid contamination by external elements such as oxygen. This preliminary step ensures that the environment remains neutral and conducive to top-quality nitriding.

Gas injection

Injection of the active gas mixture, under reduced pressure, is carefully controlled to maintain optimum mass flow. These gases, often a mixture of nitrogen or hydrogen, are used to facilitate the formation of atomic nitrogen on the metal surface.

Plasma creation

By creating a plasma ionizing the furnace atmosphere, nitrogen ions are generated, helping to pickle and heat parts. Modern furnaces, often equipped with additional heating by resistors or active grids, optimize this process to reach the required temperatures without overheating the material.

The nitrided layer comprises :

- on the surface, a combination layer, often referred to as the white layer, from 5 to 25 µm in thickness, in which the nitrogen is combined in the form of iron nitride (γ, ε or γ +ε), conferring very high hardness. This layer promotes sliding, thus increasing resistance to wear and seizure.

- an underlying diffusion layer, generally between 0.1 and 0.5 mm deep, which ensures good fatigue resistance and also enhances wear resistance. The composition and thickness of this layer depend on the steel grade and the specific treatment parameters used.

Cooling

At the end of the diffusion cycle, cooling is achieved by forced circulation of neutral gas, such as nitrogen, to ensure uniform, controlled cooling. All treatment parameters, including temperature, time, mass flow rates and plasma characteristics, are rigorously managed by an advanced computer system.

    Features and benefits of ion nitriding

    Ion nitriding offers numerous advantages for all types of steel and stainless steel parts, particularly those subject to wear, seizure and fatigue.

    fatigue resistance

    Improved surface hardness

    For parts subject to high mechanical stress, nitriding is a recommended heat treatment. This process improves surface hardness and corrosion resistance, in the case of post-oxidation, while extending the service life of treated materials.

    limited deformations

    Low processing temperature

    Thanks to the moderate treatment temperature of around 500°C, part deformation is minimized, which is crucial for maintaining the precise geometry of your components. This level of control is particularly important for parts made of stainless steel and other special alloys.

    processing on finished parts

    No re-machining required

    Ion nitriding can be carried out on parts in the hardened-tempered state, at final dimension, or with a small grinding allowance. This feature makes ion nitriding ideal for final applications where dimensional accuracy is critical. In some cases, it may be necessary to first stabilize the blank or allow for a slight machining allowance.

    Versatility

    Choosing the right steel grade

    Ion nitriding can be applied to all steel grades, including stainless steels, offering a solution for a wide range of industrial needs. This method is suitable for a variety of applications without compromising essential mechanical properties.

    savings

    Localized treatment possible

    The ease and reliability of metal shielding during ion nitriding means that specific areas are effectively protected from nitriding, ensuring that only the desired surfaces are treated. This technique is particularly useful for complex parts where certain areas must remain untreated for functional or assembly reasons.

    Information for study and order

    - Drawing of the part (possibly including: area to be protected).
    - Number of parts per shipment per year.
    - Type of steel: standard (or commercial) designation
    - Specification of the layers to be produced (with machining allowance, if any).
    - Previous treatments (pre-treated, quenched and tempered, stabilized, annealed).

    Ask for a quote

    business sectors concerned

    Typical applications: cams, extrusion screws, tooling, slides, gears and all stainless steel parts

    Our various documentations

    Heat treatment white paper

    The ion nitriding process

    See all our documentation

    Our FAQs

    Why nitriding/nitrocarburizing?

    Diffusion of nitrogen on the surface of the part to considerably improve mechanical strength and wear resistance on the surface, while maintaining good core strength. This treatment greatly improves wear resistance, but as the temperature is low (500°C), it causes very little deformation and can be applied to a finished part.

    How is heat treatment carried out? 

    Heat treatment is carried out using furnaces. There are air, atmosphere, vacuum, plasma and induction furnaces.

    What are the main types of heat treatment?

    There are two main types: softening treatments to improve the shaping or machining of parts, modify or improve the metallurgical structure or defragilize certain mechanisms. Hardening treatments in the mass or on the surface to improve the mechanical performance of components.

    What do I need to know when requesting or placing an order for heat treatment?

    Type of steel, desired steel characteristics (hardness), quantity of parts per shipment and per year, part drawings and specifications. If possible, the operating mode of the part and its final use.

    See all FAQs

    Do you have a question or a need?

    Our dedicated team can handle any ion nitriding project.

    Contact us

    Our latest news

    Discover Thermilyon Group news and our best articles on heat treatment.

    mechanical parts with vacuum coating
    How to choose the right vacuum coating to improve the performance of mechanical parts?
    In high-tech sectors such as aeronautics, automotive, medical and precision industries, the performance expectations of mechanical components have never been higher. Resistance to wear and seizure, protection against corrosion, reduction of the coefficient of friction: these technical requirements are driving manufacturers to seek out surface treatments capable of [...].
    July 1, 2025
    How to choose the right vacuum coating to improve the performance of mechanical parts?
    man on a car parts assembly line
    Heat treatment and part lightening: what solutions for the automotive industry?
    Today, lightweighting is a strategic lever for the automotive industry, at the crossroads of environmental, technological and economic challenges. Meeting these challenges without compromising the mechanical performance of components requires perfect mastery of heat and surface treatments. Why is lightweighting a key issue for the automotive industry? Regulatory and economic pressure [...]
    June 2, 2025
    Heat treatment and part lightening: what solutions for the automotive industry?
    image of a red leather belt with a metal buckle to illustrate PVD treatments for the luxury and decorative sectors
    PVD treatment: a revolution for the luxury and decorative sectors
    In a world where aesthetics is a fundamental criterion, the luxury and design industries are looking for technical solutions capable of enhancing their creations while guaranteeing durability and precision. PVD treatments, once the preserve of technical fields such as aeronautics and medicine, are now becoming a strategic asset in the most [...]
    May 16, 2025
    PVD treatment: a revolution for the luxury and decorative sectors
    impact of medical certifications on heat treatment
    What is the impact of heat treatment certification in the medical sector?
    In the medical sector, every component, every device, every material is subject to stringent requirements. When it comes to heat treatment, these requirements are not limited to surface quality or mechanical resistance. They encompass traceability, process reproducibility and compliance with international standards. This is where [...]
    May 7, 2025
    What is the impact of heat treatment certification in the medical sector?
    aeronautical supply chain challenges in île-de-france
    The challenges of the aeronautical supply chain in the Paris Region
    Aeronautics is one of the world's most demanding sectors, and the Paris Region is one of its most dynamic industrial hubs. At the crossroads of innovation, precision and performance, the region's aeronautical supply chain plays a key role in the competitiveness of the French industry. To meet the needs of manufacturers [...]
    April 15, 2025
    The challenges of the aeronautical supply chain in the Paris Region
    Electric car being charged
    Mechanical components of an electric car
    Electric cars have profoundly transformed the automotive industry by rethinking traditional mechanical principles. Unlike internal combustion vehicles, which rely on a combustion engine, these vehicles run on an electric motor powered by a battery. This change has led to a major evolution in the design of mechanical components, which must be adapted to the new [...]
    March 4, 2025
    Mechanical components of an electric car