Can You Weld with Nitrogen?

No, you cannot weld carbon steel, aluminum, or stainless steel with pure nitrogen because it causes severe porosity, arc instability, and brittle welds. The only exception is copper and certain copper alloys, where nitrogen actually provides adequate shielding.

While nitrogen fails as a primary shielding gas, it has specific uses in welding operations – including back purging stainless steel pipes, plasma cutting, and as a controlled additive (1-3%) in argon for duplex stainless steels.

Below, you will learn:

• Why you can’t TIG or MIG weld with pure nitrogen
• What happens when nitrogen becomes reactive at arc temperatures
• How nitrogen is actually used in welding operations
• When to add nitrogen to your shielding gas mix for specific alloys
• Which metals benefit from nitrogen (and which ones don’t)

Can You Weld with Pure Nitrogen?

No, you cannot use pure nitrogen as a primary shielding gas for standard welding operations because it causes porosity, arc instability, and brittle welds on most metals. The only exception is copper and certain copper alloys, where nitrogen actually provides adequate shielding.

Can You TIG Weld with Nitrogen?

TIG welding with pure nitrogen fails on almost all metals except copper. The nitrogen creates severe porosity and makes the arc nearly impossible to control.

When nitrogen hits your tungsten electrode at high temperatures, it causes immediate problems. The arc becomes erratic and jumps around unpredictably. Your tungsten deteriorates much faster than with argon.

The real damage shows up in your finished welds. Nitrogen dissolves into the molten metal and forms gas bubbles as the weld cools. These bubbles create porosity throughout the weld, making it weak and prone to cracking.

Professional fabrication shops never use pure nitrogen for TIG welding their standard inventory. They stick with pure argon or argon-helium mixes to ensure consistent quality across different metals.

Can You Use Nitrogen for MIG Welding?

No, you cannot use pure nitrogen for MIG welding because it causes arc instability, excessive porosity, and poor weld quality on virtually all metals. The continuous wire feed and higher heat make nitrogen completely unsuitable for MIG processes.

Your MIG arc becomes unstable immediately with pure nitrogen. The wire doesn’t transfer smoothly to the base metal. You’ll get excessive spatter and irregular bead appearance.

The porosity issues are more severe with MIG than TIG. The faster welding speed and continuous arc trap more nitrogen in the weld pool.

Why Nitrogen Doesn’t Work as a Primary Shielding Gas

Nitrogen becomes reactive at typical welding arc temperatures, unlike truly inert gases like argon. It forms brittle nitrides with iron, aluminum, and titanium that concentrate at grain boundaries and cause cracking.

Nitrogen also lacks the ionization characteristics needed for arc stability. It requires different voltages than argon and creates an unstable plasma column. This makes consistent arc control impossible, regardless of your welding parameters.

What Is Nitrogen Gas Used for in Welding?

In welding operations, nitrogen works as a purge gas, a controlled additive to shielding mixes, and the main gas for plasma cutting.

Back Purging Stainless Steel

The most common use is back purging stainless steel pipes and tubes. When you weld stainless steel, the back side of the weld needs protection from oxidation too. Nitrogen costs less than argon for this application and provides adequate protection.

Manufacturing facilities pump nitrogen through the inside of pipes while welding the outside. This prevents sugaring (oxidation) on the root pass. The weld stays silver and clean instead of turning black and scaly.

Adding Nitrogen to Shielding Gas Mixes

Nitrogen gets mixed with argon in small percentages for specific applications. Adding 1-3% nitrogen to argon improves corrosion resistance when welding duplex stainless steel. The nitrogen helps maintain the proper austenite-ferrite balance in these alloys.

Food processing plants and pharmaceutical facilities often use these controlled nitrogen mixes. They need the enhanced corrosion resistance for equipment that contacts aggressive chemicals or cleaning solutions.

Plasma Cutting Operations

Plasma cutting systems use nitrogen as the cutting gas for stainless steel and aluminum. The high-velocity nitrogen jet blows molten metal away while preventing oxidation of the cut edge. This leaves a clean, weldable edge that doesn’t require grinding.

Manufacturing facilities choose nitrogen for plasma cutting because it produces better cut quality than compressed air on stainless steel. The cuts are smoother with less dross adhesion to the bottom edge.

When to Add Nitrogen to Your Shielding Gas Mix

You should add nitrogen to your shielding gas mix only for specific materials and applications where the metallurgical benefits outweigh the risks. Standard carbon steel, aluminum, and most stainless steels perform worse with nitrogen additions.

• Duplex and super duplex stainless steel: add 1-3% nitrogen to maintain the austenite-ferrite phase balance during welding. Without nitrogen, the heat-affected zone becomes too ferrite-rich and causes pitting corrosion when exposed to chlorides.
• High-nitrogen austenitic stainless steels: add 1-2% nitrogen when welding grades like 316LN or 304LN to prevent nitrogen loss from the base metal. These alloys contain over 0.15% nitrogen for enhanced strength, and welding heat drives it out without proper shielding.
• Copper and copper alloys: pure nitrogen works as a primary shielding/purging gas because copper doesn’t readily form nitrides with nitrogen, unlike iron, aluminum, or titanium. HVAC contractors use nitrogen for copper pipe joints when argon isn’t available, providing adequate shielding at lower cost. The welds hold pressure and conduct electricity properly despite rougher appearance.

Always purge your gas lines completely when switching between mixes – residual argon dilutes the nitrogen percentage.

Conclusion

Pure nitrogen doesn’t work for welding steel, aluminum, or stainless steel – it causes porosity, arc instability, and brittle welds. The only metals you can weld with pure nitrogen are copper and certain copper alloys.

Nitrogen has legitimate uses in welding operations: back purging stainless pipes, small additions to argon for duplex stainless, and plasma cutting. But it should never be your primary shielding gas except for copper work.

If you need nitrogen additions, use pre-mixed cylinders from your gas supplier. This ensures the right percentage and eliminates costly mistakes.

Lawrence Haynes

Currently serving as Marketing Director at WestAir Gases & Equipment in San Diego, CA Lawrence leverages his expertise in industrial gas solutions and equipment marketing. With a proven track record in cross-industry marketing strategy, he brings a specialized experience in content development, marketing automation, and partner relations to the industrial gas sector.