Why Isn't Nitrogen Commonly Used as a Shielding Gas in Welding Instead of Argon?

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Discussion Overview

The discussion revolves around the use of nitrogen versus argon as shielding gases in welding processes. Participants explore the chemical properties of both gases and their implications for welding, focusing on the reasons why nitrogen is not commonly used despite its potential cost advantages.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions why nitrogen is not used instead of argon, suggesting that nitrogen might be cheaper.
  • Another participant notes that nitrogen can react with air at high temperatures to form nitrous oxides, which could be detrimental, and raises the possibility of nitrogen forming nitrides with the metal.
  • A later reply acknowledges the previous point, suggesting that this is likely the reason for the lack of nitrogen use.
  • One participant elaborates that nitrogen behaves as a "fake" inert gas, only acting inert at lower temperatures due to its stable triple bond, but can react at higher temperatures typical in welding, unlike argon, which is a true inert gas.

Areas of Agreement / Disagreement

Participants express differing views on the inertness of nitrogen at high temperatures, with some agreeing on its limitations while others highlight its potential cost benefits. The discussion remains unresolved regarding the overall suitability of nitrogen as a shielding gas.

Contextual Notes

There are assumptions regarding the temperature ranges of welding processes and the specific reactions of nitrogen that remain unverified. The discussion does not resolve the potential for nitrogen's use in specific contexts or applications.

cragar
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Why don't they use nitrogen for welding instead of argon . Unless it does something to the metal . Nitrogen seems like it would be cheaper than argon .
 
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Nitrogen reacts with air at high temps to form nitrous oxides which aren't nice.
Not sure if they could form nitrides with the metal but they might

Argon is also heavy enough that it doesn't disperse too quickly
 
thanks for your answer , so that's probably why they don't use it .
 
Nitrogen is only a good inert gas for medium to low temperature processes. It's almost like a "fake" inert gas, because it only acts like an inert gas because it has a triple bond in its structure which is very hard to break, so it will not react in lower temperatures.

At around 1500C it will react with the air to form oxides of nitrogen, meaning it is no longer inert. Welding processes can create temperatures into several thousands of degrees. Argon on the other hand is a noble gas, having a full valence shell and is a true "inert gas" and will not react at any temperature.
 

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