Neutral Annealing

Linde's CARBOFLEX™ annealing atmospheres are available in various mixtures of nitrogen and endothermic gas or methanol. In some cases other hydrocarbons such as natural gas or propane can be used.

These atmospheres are normally used for bright or neutral annealing with strong requirements on control over decarburization of high alloy steels. For continuous annealing of steel coils, Linde has developed the CARBOFLEX-RHF system.



Pure Nitrogen is preferred for annealing of some steels, cast irons, copper and aluminum. Linde has the knowledge to optimize nitrogen flow and minimize oxidation and discoloration of aluminum strip coils.

Linde's HYDROFLEX is suitable for stainless steel where either 100% hydrogen is used when the high surface quality is required or a mixture containing nitrogen or argon to precisely match the quality demands with the most cost effective gas composition.

100% hydrogen is also used to minimize annealing time in bell furnace annealing of mild steels or brass strip coils. Bright annealing of mild steels is done in HYDROFLEX with low hydrogen concentration, typically 10% (by volume). In decarburization annealing water is added to the mixture of nitrogen and hydrogen.