Nitrogen as a shielding gas

[smithdoor]

Here some I found for using Nitrogen

Dave

Why don't they use Nitrogen as a shielding gas for welding instead of argon . Unless it does something to the metal . Nitrogen seems like it would be cheaper than argon . Jan 13, 2011 #2 NobodySpecial 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

Reference https://www.physicsforums.com/thread...ng-gas.463064/

[smithdoor]

Nitrous oxide has significant medical uses, especially in surgery and dentistry, for its anaesthetic and pain reducing effects. Its name "laughing gas", coined by Humphry Davy[clarification needed], is due to the euphoric effects upon inhaling it, a property that has led to its recreational use as a dissociative anaesthetic. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system.[2] It also is used as an oxidizer in rocket propellants, and in motor racing to increase the power output of engines.

[davec]

Jezuz. Think about it. If after like 100 yrs of welding with electricity, and they don't use nitrogen, don't you think there is a reason why? Nitrogen is not inert like Argon. The inert gasses are in the far right of the periodic table - Helium, Argon, Neon, Krypton, Xenon... Nitrogen is used in chemistry as a lot of times you don't want oxygen present, so it displaces oxygen for your experiments or reactions. That doesn't make it inert but rather that it does not affect the reaction in question. Some times nitrogen WILL affect the reaction you are working on, and then you typically go to Argon (the cheapest of the inert gasses). You strike an arc and INERT is really important, and nitrogen will react with other things in that state. Not a chemist, but done enough of it. And really - if there was a cheaper option than argon, don't you think all welding would use that? Not trying to be a d!ck but if you think it through, it should be pretty clear they are't using it for fun.

[M J D]

Nitrogen is used in portion for some stainless steel gas mixes. Also used for plasma cutting in some heavier applications. It can also be used for purging, altho I'm not sure how popular that is, as argon is more often used.

[ttoks]

Using nitrogen as a shielding gas causes will cause the steel to become overly brittle, all steel has SOME nitrogen in it as it will dissolve into the steel at high temperatures during smelting and a controlled amount of it is desirable, and some steels intentionally have fairly high nitrogen content as an alloy when added in addition to something else like Valadium, the nitrogen bonds with the valadium to form a valadium nitrite.

also its pretty common to have the surface of steel treated with some sort of nitrogen or nitrite to get a very hard and wear resistant finish without adding another layer on top of a finished part, as the nitrogen bonds with the steel itself rather then sitting on top of it, think hydraulic cylinders and such.

but yeah, pretty much using nitrogen as a shielding gas causes to much of it to dissolve into the metal alloying with it and it will crack.

It's funny you mention that nitrogen is used in some stainless mixes as well, during world war two nitrogen was sometimes used in place of nickle for stainless steel as nitrogen does increase the corrosion resistance as well.

If your interested, do some reading here. http://ispatguru.com/nitrogen-in-steels/ but an excerpt from the article on welding.

"Effect during welding – Nitrogen generally affects the toughness of the heat affected zone (HAZ) of welded steel. Since the weld metal should not be weaker in a welded structure, the role of nitrogen is important. The loss of toughness is normally known as HAZ embrittlement. It is thought this occurs when the nitrides present in the HAZ are dissociated as a result of the elevated temperatures that exist during welding. The absence of precipitates results in grains of larger diameter. Also, the metal cools quickly producing low toughness martensite or bainite, which contain high levels of free nitrogen further exacerbating the loss of toughness. Using lower heat input and several passes to prevent dissociation of the nitrides can prevent this."

[smithdoor]

air is about 80% Nitrogen
both Open hearth furnace and Bessemer use air

Dave

Using nitrogen as a shielding gas causes will cause the steel to become overly brittle, all steel has SOME nitrogen in it as it will dissolve into the steel at high temperatures during smelting and a controlled amount of it is desirable, and some steels intentionally have fairly high nitrogen content as an alloy when added in addition to something else like Valadium, the nitrogen bonds with the valadium to form a valadium nitrite.

also its pretty common to have the surface of steel treated with some sort of nitrogen or nitrite to get a very hard and wear resistant finish without adding another layer on top of a finished part, as the nitrogen bonds with the steel itself rather then sitting on top of it, think hydraulic cylinders and such.

but yeah, pretty much using nitrogen as a shielding gas causes to much of it to dissolve into the metal alloying with it and it will crack.

It's funny you mention that nitrogen is used in some stainless mixes as well, during world war two nitrogen was sometimes used in place of nickle for stainless steel as nitrogen does increase the corrosion resistance as well.

If your interested, do some reading here. http://ispatguru.com/nitrogen-in-steels/ but an excerpt from the article on welding.

"Effect during welding – Nitrogen generally affects the toughness of the heat affected zone (HAZ) of welded steel. Since the weld metal should not be weaker in a welded structure, the role of nitrogen is important. The loss of toughness is normally known as HAZ embrittlement. It is thought this occurs when the nitrides present in the HAZ are dissociated as a result of the elevated temperatures that exist during welding. The absence of precipitates results in grains of larger diameter. Also, the metal cools quickly producing low toughness martensite or bainite, which contain high levels of free nitrogen further exacerbating the loss of toughness. Using lower heat input and several passes to prevent dissociation of the nitrides can prevent this."

[ttoks]

air is about 80% Nitrogen
both Open hearth furnace and Bessemer use air

Dave

the bessemer process was phased out for the open hearth, open hearth gave greater control over the steel production and introduced far less nitrogen, open hearth was phased out due to cost.

I'm not exactly sure what your trying to imply? is it that nitrogen is good for welding or that it's irrelevant because old technology used air rather then pure oxygen in steel production?

[smithdoor]

I have read so parts of world uses nitrogen

I have never try nitrogen, most time use co2 and some time Argon

Dave

[Munkul]

As said, it's not a true inert gas, but it is useful up to the temperature where it breaks down.
It does react with metals, can be good or bad, in fact it improves pitting corrosion resistance in duplex steels during manufacturing when controlled correctly (promotes the austenite formation).

they use it as the inert gas in laser cutting systems because a) it is very, very cheap to produce; and b) the heat input to the workpeice material is low enough that reacting with N2 doesn't matter.

[smithdoor]

I look at using Nitrogen due to my argon is fill with nitrogen and just hate to open valve and let it go.

So did searching and some parts of world do use nitrogen

But why do they use nitrogen and the USA does not use this gas.
If look at all place that nitrogen had been use but no longer use in the USA

Dave

As said, it's not a true inert gas, but it is useful up to the temperature where it breaks down.
It does react with metals, can be good or bad, in fact it improves pitting corrosion resistance in duplex steels during manufacturing when controlled correctly (promotes the austenite formation).

they use it as the inert gas in laser cutting systems because a) it is very, very cheap to produce; and b) the heat input to the workpeice material is low enough that reacting with N2 doesn't matter.

[Munkul]

the US is backwards in some ways maybe?

I dont understand your post.

No-one's saying it's a replacement for argon in MIG/MAG/TIG welding, because it isn't. If it could be, it already would be.

Two local fab shops I know have huge laser cutting systems and they have gone a step further in buying nitrogen generators for producing N2 on site instead of going through 40-50 bottles per week.

[smithdoor]

Find why USA only use nitrogen in blended gas.

Dave

the US is backwards in some ways maybe?

I dont understand your post.

No-one's saying it's a replacement for argon in MIG/MAG/TIG welding, because it isn't. If it could be, it already would be.

Two local fab shops I know have huge laser cutting systems and they have gone a step further in buying nitrogen generators for producing N2 on site instead of going through 40-50 bottles per week.

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