Heat Treatment
Safe, reliable and customised solutions
Most metal parts made of steel or other alloys used in industry have been subjected to one or more heat treatment cycles in order to improve their surface and structural mechanical properties.
Steels and metal alloys in general need to be protected against oxidation and decarburisation (for carbon steels) during heat treatment. Our solutions are designed to deliver parts with mechanical properties (hardness, toughness, wear and corrosion resistance, etc.) that meet customer specifications.
Which is your key Heat Treatment industrial priority?
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Designed for Strict Quality Control
Tailor-made Solutions
Our gas, equipment and range of services help you generate, use and control the atmosphere in industrial furnaces for heat treatment processes.
Reliability
We deliver safe, reliable and tailored gas solutions up to the point of use with maintained gas quality. Our robust LIN infrastructure comprises of cryogenic services to support deep cooling and we work with you to achieve custom atmosphere conditions that will give you the desired metal surface finish quality.
Quality Standards
We also help you comply with the strict rules and safety requirements that apply in heat treatment. You may engage our furnace atmosphere checking services to be CQI-9 industry standard compliant.
Specific Expertise
Our experts have extensive technical knowledge of your processes and are ready to help analyse problems, offer support for safe installations and increase productivity.
Carburising
Surface hardening processes for steels via gas carburising need to be increasingly competitive, environmentally friendly and ensure more consistent and uniform results — all the while achieving uniform surface hardness of the entire part.
Atmospheric carburising
Classic heat treatment
Carbon is used to obtain a martensitic surface layer on the steel after quenching.
➜ ALNAT™ Heat Treatment Solutions
Low pressure carburising (LPC)
Also known as case hardening or carburisingThe process increases surface concentration of carbon in the treated steel part, thereby increasing surface hardness. Vacuum heat treatment is carried out under low pressure in vacuum ovens with acetylene as the most common carbon source.
➜ ALNAT™ Heat Treatment Solutions
Nitriding
Automotive, mechanical and aerospace industrial sectors are registering a growing demand for functional parts with specific mechanical properties. Gas nitriding of Steels and Iron alloys comes in various forms: plama-assisted ionic nitriding, salt baths, gas at atmospheric pressure or in low pressure ovens.
Quenching and tempering
After carburising or carbonitriding process, the metal parts must be cooled quickly and in a controlled manner. Gas quenching enhances efficiency and safety with a faster cooling rate, eliminating the constraints of oil quenching tanks and the associated risks of oxidation. It also eliminates the need to wash the parts on the surface after treatment.
Quenching with conventional fluids (oil baths, polymers, molten salt baths, water, etc.) after heat treatment may not yield satisfactory results. To obtain quality and highly consistent results, gas quenching is recommended.
Subzero treatment
Cryogenic or Subzero treatment is an additional operation during the Hardening process of steel parts after quenching and before tempering. The main effect of this treatment is to complete the transformation of residual austenite into martensite. Main benefits are: Improved dimensional and structural stability, Increased hardness and wear resistance, Possible suppression of one tempering cycle.
Subzero treatment is realized inside a cryogenic chamber operating with liquid Nitrogen as the cooling medium and working at a temperature range of -80°C to -120°C. The chambers are usually fed by a liquid Nitrogen tank and a vacuum insulated pipe to avoid cooling losses. Some chambers will have integrated electrical heating to reheat the parts directly inside the same equipment after the subzero treatment.
Stainless steel, carbon steel and non-ferrous metals undergo annealing (with Nitrogen, Hydrogen or Forming Gas) to reduce stress, restore structure after machining and achieve desired material properties.
Sintering
Metal powder sintering is very versatile and requires a lot of attention at each stage:
- the choice of metal powders
- the binder
- the tools to make the preform
- the debinding method (thermal or chemical)
- working parameters to control the dimensional variation of the material
- the rate of residual porosity
The different atmospheres in sintering
| Zone | Debinding | Hot sintering | Cooling |
|---|---|---|---|
| Gas used | N₂ + H₂ with injection of an oxidising element such as H₂O (humid gases) | N₂ + H₂ + CH₄ | N₂ |
| Purpose | Increase the dew point and promote the elimination of the binder | Avoid oxidation. The controlled addition of methane makes it possible to adjust the carbon flow and avoid decarburisation. |
Prevent oxidation to obtain a shiny surface. |
Our recommended gas and equipment solutions for heat treatment
We are proud to provide customers with competitive gas solutions that are safe, reliable and fine-tuned to their needs. Air Liquide ALNAT™ solutions are robust and repeatable, adaptable to furnace operations and guarantees optimisation of the Heat Treatment Atmosphere. As a customer, you will benefit on how to work safely with flammable, toxic and inert gases. Master your quality by understanding the furnace atmosphere and improve productivity by knowing your furnace performance.
Related Gases
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