Controlled gas cementation

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gas cementation

Objective: precise control of cemented layer characteristics and depth.

Gas carburizing, a crucial heat treatment, enriches the steel's surface layer with carbon, essential for increasing wear and fatigue resistance at the surface. This process can also incorporate nitrogen for carbonitriding, increasing surface hardness while maintaining good core mechanical properties. Hardening, carried out after case-hardening, is essential to achieve high hardness performance and durability, while controlling the deformations associated with rapid cooling and martensitic transformation.

Traditionally carried out in a nitrogen-methanol atmosphere, Thermi-Lyon's innovative Thermi-Carb® gas carburizing process uses a controlled mixture of active gases (such as CH4) and air, optimizing carbon diffusion and the gaseous phase of the treatment. The process is computerized for precise parameter control, ensuring excellent control of operations and results in an industrial environment.

automatic oven line trempelec, bach oven

Our process

Depending on the number, size and configuration of parts, and the desired treatment depth, various types of furnace are used, such as pot furnaces, batch furnaces (with integrated quench tank), and conveyor furnaces. The "Thermi-Carb®" process, specially developed by the THERMILYON Group, is particularly well suited to pot and batch furnaces, optimizing carburizing and carbonitriding of mechanical components. A nitrogen-methanol atmosphere is traditionally used for belt furnaces, favoring high-precision heat treatment.

Pressure and temperature control

The treatment is carried out at slightly above atmospheric pressure, operating at high temperatures of 900 to 940°C for carburizing and 820 to 900°C for carbonitriding. These precise settings produce a high-quality case-hardened layer, increasing mechanical strength and surface hardness while minimizing the risk of inter-granular oxidation.

Continuous management

An advanced computer system continuously monitors crucial process parameters such as time, temperature and composition of the active atmosphere. The use of an oxygen probe or an infrared analyzer for CO and CO2 enables precise calculation of the carbon potential, ensuring uniformity of the surface layer and consistent quality of surface and core mechanical characteristics, tailored to each steel grade.

Recommendations

For mild and medium-hard steels (C10 to C45, A40 to A60), case-hardening is generally not recommended due to their low hardenability, which can lead to incompatibilities between core and surface hardness, as well as heterogeneities in the case-hardened layer. Carbonitriding, on the other hand, is recommended for free-cutting steels such as C10, S300 and S300 Pb, as the addition of nitrogen during this process enables higher surface hardnesses to be achieved, offering improved wear resistance.

Features and benefits

Gas carburizing significantly improves surface wear and fatigue resistance, while maintaining excellent core strength properties. This method, which focuses on enriching the surface layer of metals with carbon, also enhances the durability and performance of treated components.

Mechanical resistance

Thermi-Lyon's case-hardening and carbonitriding processes deliver high levels of wear, seizure and fatigue resistance, even in low-cost steels with good machinability. This approach guarantees high quality and reliability for a wide range of industrial applications, including demanding sectors such as automotive and public works.

Precision

We offer high precision and reliability in the reproduction of heat treatments, thanks to our mastery of advanced techniques and the diversity of technologies adapted to different types of parts, including pot, batch and belt furnaces. These technologies ensure consistent, cost-effective results, boosting competitiveness in the marketplace.

Deformation control

Uniformity of the treated layer and controlled depth of treatment are essential to maintain hardening performance. Martensitic transformation can lead to dimensional variations; however, the rigorous control of our Thermi®-Carb process, in combination with the latest generation of oil quenching devices, minimizes these deformations. This level of control is crucial to ensuring the quality and precision of processed parts, enhancing their durability and operational efficiency.

For study and order

Information to be communicated :

Type of treatment: case-hardening or carbonitriding.

- Drawing of the part, specification, weight, number of parts per shipment and per year.
- Nature of the metal. Preferred AFNOR or commercial designation.
- Conventional depth and surface hardness (core hardness results from steel grade).
- Deformation tolerance (with possible straightening and allowance for finish machining).

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business sectors concerned

Gaseous carburizing and carbonitriding are widely used for mechanical parts subjected to fatigue and friction (wear resistance and seizure).

Aerospace

Automotive

Rail energy

Machines and components

Medical

Tools

Sports and leisure

Public works

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