Annealing  [ Return towards  Metal Fabrication Industries  ]

To avoid oxidation and/or decarburization during the process, a protective atmosphere is required in the furnace.

ALNAT Atmosphere solutions for annealing are mainly based on Nitrogen / Hydrogen / Hydrocarbon or Nitrogen / cracked Methanol mixtures. Nitrogen, the main component for such an ALNAT atmosphere, provides the inert base and prevents oxidation from occurring, and hydrogen, a reducing agent, will ensure a clean and bright surface, whilst the presence of carbon species will enable the decarburization to be controlled. Depending on the metal and required properties, the hydrogen level will be ajusted between 5% (non ferrous) and 100% (stainless steel).

Nitrogen and Hydrogen can be delivered from standard liquid or gaseous storage, but also from a FLOXAL unit, an on-site production system incorporating the latest technology available within the Air Liquide Group.

The atmosphere composition and flow rates will be adjusted close to the requirements of the metal being annealed and the furnace characteristics with the help of Air Liquide's heat treatment experts. Further services can also be provided on request.

The atmosphere is delivered to the furnace by a flow control panel, which includes all necessary safety controls. When the furnace is running continuously, atmosphere zoning solutions can be put in place to optimize gas consumption, especially hydrogen, while ensuring the highest quality product.

To be even more cost effective, Air Liquide has developed the ALNAT Endo concept, a flexible ready-to-use atmosphere containing hydrogen, carbon monoxide and nitrogen.

Benefits of the ALNAT solutions include improved safety, low-maintenance operation and a reliable and competitive atmosphere at low capital cost.