Gas solutions for heat treatment processes
Air Liquide offers gas and equipment as well as a range of services to help you generate, use and control the atmosphere in industrial furnaces for your hearth process, all to help you optimize your business and your costs. We also offer support from our experts who have extensive technical knowledge of your processes.
Our tailor-made solutions are safe and reliable with maintained gas quality up to the point of use. We also help you comply with the strict rules and safety requirements that apply in heat treatment.
With our service ALNAT™ Audit, where we analyse gas composition in the process and perform temperature uniformity measurement, you get, for example, a third-party analysis to meet the CQI-9 standard.
Carburising / Low pressure caburizing (LPC)
In carburising and carbonitriding, carbon is used to obtain a martensitic surface layer on the steel after quenching.
Low pressure carburising, or low pressure carburising (LPC), is a further development of the classic heat treatment, usually referred to as case hardening or carburising. The purpose of the process is, just as before, to increase the surface concentration of carbon in the treated steel part, and thus the surface hardness.
As the name suggests, the treatment is carried out under low pressure, 5-30 mbar, and is carried out in vacuum ovens. The carbon source used is usually acetylene, which is released in small pulses into the furnace chamber during treatment.
Low-pressure carburising is often combined with a final quenching in gas at high pressure (15-30 bar). Nitrogen (N 2 ) is the most common gas used, but helium (He), together with a recycling system, also occurs.
The advantages of low-pressure carburising and gas cooling include:
- Cleaner and environmentally more sustainable process
- Reduced and smoother shape change
- Better carburisation of hole geometries
Air Liquide has good experience in both installations and gas delivery to furnaces with low-pressure carbonisation.
Extinguishing / cooling with gas
Carburizing, annealing and nitriding are all heat treatment processes that are usually finished with a quench. The rapid cooling can be carried out using gas, usually nitrogen, but helium can also be used. Extinguishing with gas is an environmentally friendly alternative to extinguishing with oil or salt solution.
In processes such as carburizing, annealing and nitriding, quenching with gas provides a better opportunity to control the process and reduces the need for subsequent machining/adjustment.
Air Liquide's application for deep cooling, Nexelia Cryogenic Treatment, cools the product down to below -180 °C and increases resistance to abrasion, pitting damage and cracking and reduces residual stresses in the material. The application provides a controlled process with a high degree of safety, efficiency and reliability.
Our ALNAT™ solutions for annealing are mainly based on gas mixtures containing nitrogen, hydrogen and hydrocarbon or nitrogen and cracked methanol. The advantages of ALNAT are safety, reliability, less maintenance and lower investment costs. Stainless steel, carbon steel and non-ferrous metals are annealed to reduce stresses, restore the structure after machining and to achieve desired properties in the material.
Air Liquide offers ALNAT™ which includes the gases, gas equipment and services you need for your inerting process.
Air Liquide offers our own EGAL (Expanding Gas Air Liquide) process which uses liquid gas (argon or nitrogen) to limit contact between the molten metal and the surrounding atmosphere. Air Liquide's SPAL technology for inerting the melt results in fewer defects and improved mechanical properties of the metal as well as reduced cassation during casting.
Extrusion Dies Inerting and cooling the mold in aluminum extrusion processes can increase productivity and reduce defects caused by oxidation.
Service for heat treatment
Heat treatment of steel and metal is one of Air Liquide's major areas of competence where we assist with gas deliveries, equipment and knowledge regardless of the type of heat treatment involved.
ALNAT™ Audit is a service program containing annual gas and temperature analyzes of heat treatment furnaces.