Why does vacuum heat treatment always use nitrogen?

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Vacuum heat treatment usually requires the use of nitrogen as the treatment atmosphere, mainly for the following reasons:
Prevent oxidation: Nitrogen can form a protective oxide layer at high temperatures to protect metal products during heat treatment from chemical reactions such as oxidation and carbonization.

At high temperatures, metal products easily react with oxygen in the air, leading to the formation of surface oxide layers and affecting product quality and performance. Nitrogen can replace air to form a protective nitrogen atmosphere, thereby effectively preventing oxidation reactions from occurring. In other words, it can reduce oxidation and degassing, thereby reducing adverse effects such as deformation and cracks of the treated parts.

Promote uniform heating and cooling: During vacuum heat treatment, uneven heating and cooling rates often lead to product deformation, cracking and other quality problems. By adding nitrogen to the vacuum, the uniform distribution of heat can be promoted to ensure a uniform temperature of the product and avoid problems caused by uneven heating and cooling.

Adjusting the treatment temperature: Nitrogen can adjust the treatment temperature during the heat treatment process and improve the effect of heat treatment.

Prevent hydrogen embrittlement: Nitrogen can prevent hydrogen embrittlement during heat treatment and ensure the quality of treated parts.

Prevent fires and explosions: Some metal materials are prone to burning or exploding at high temperatures. Nitrogen can be used to reduce this risk. In a vacuum, since oxygen and other gases are extracted, even if combustion occurs, it will not cause a fire or explosion.

In short, nitrogen plays a very important role in vacuum heat treatment, which can effectively protect the quality and performance of products, while improving the efficiency and effect of heat treatment, avoiding safety risks, and avoiding adverse effects during the treatment process.