The primary reason for using pure argon gas instead of nitrogen in industrial processes is the major benefits of its chemical inertness and physical characteristics. ISO 14175 states that the purity of argon is ≥99.996% (residual oxygen ≤5ppm, nitrogen ≤10ppm), whereas nitrogen even with high purity (99.999%) contains trace active ingredients (like oxygen ≤2ppm). Shelby pure argon gas in TIG welding also has an ionization energy (15.76eV) 8% higher than nitrogen (14.53eV), stabilizes the arc and reduces spattering, reducing weld porosity from 3% of nitrogen to 0.5% (ASTM E466 test). Boeing reports that with the use of argon to weld airplane aluminum alloy (AA6061), weld tensile strength is 330MPa (nitrogen only 290MPa), and fatigue life improves by 40%.
Chemical stability imbalance: nitrogen under high temperatures will react with titanium, zirconium and other metals to form nitride (e.g., TiN, hardness HV 2000), causing embrittlement of the material. During the 2023 SpaceX starship fuel tank welding accident, replacement with pure argon gas reduced the level of nitride in the titanium alloy weld from 0.15% to 0.02% (X-ray diffraction analysis), reducing the potential for hydrogen embrittleness by 87%. Nitrogen will cause Cr₂N precipitation (chromium loss rate > 12%), chromium retention rate under argon protection ≥99.8% (EDX energy spectrum data), corrosion rate (ASTM G48) from 0.12mm/year to 0.03mm/year.
Comparison of thermodynamics: thermal conductivity of argon (0.0177W/m·K) is 36% less than that of nitrogen (0.024W/m·K), and solidification time of molten pool of laser welding can be increased by 30%-50%, and thermal cracking possibility can be reduced (from 15% to 3%). Germany’s TRUMPF tests show that, when 5mm thickness of mild steel is welded using a pure argon gas 12kW fiber laser, penetration consistency standard deviation is reduced from ±0.3mm to ±0.1mm and processing efficiency is enhanced by 22%.
Economy and suitability for applications: Pure argon gas unit price (1.2/m)
It is 300% higher than nitrogen (0.3/m³), but in high-precision applications, the overall cost is lower. For example, while sputtering semiconductor wafers, nitrogen with silicon was reacted to form Si₃N₄ (dielectric constant 7.5). Argon was non-reactive. Target utilization was increased from 75% to 95% (Applied Materials data). TSMC data indicate that the defect density (< 0.1/cm²) of the metallized layer of the 7nm chip with argon is only half that of the nitrogen process (0.5/cm²), the yield improves by 8%, and the cost savings are $260 million per year.
Safety and regulatory requirements: Nitrogen poses a choking risk in confined Spaces (risk is less than 19.5% oxygen), while pure argon gas is more leak-sensitive in welding (research by TWI shows that argon sensors respond 0.8 seconds faster than nitrogen). Argon or helium needs to be used as a shielding gas for aviation welding as per the EU EN 439 standard, while nitrogen is prohibited. In 2024, the Airbus A320neo production line was switched to argon after a direct loss of €4.2 million because of nitrogen embrittle in the landing gear welds due to improper use of nitrogen.
Environment and sustainability: Nitrogen production (air separation) takes 0.35kWh/m³, while argon production (co-production) takes 0.4kWh/m³, but argon recovery is 90% (nitrogen recovery only 60%). After argon circulation system was installed in Japan’s JFE plant, procurement volume on yearly basis was reduced by 18,000 m³ and the carbon impact reduced by 480 tons of CO₂e (6,500 trees). Tesla’s German factory in Berlin utilizes a closed-loop recycling pure argon gas unit to reduce single-vehicle welding gas costs by €12 and reduce emissions by 1,200 tonnes yearly.
From micro reactions to macro benefits, pure argon gas has become the inevitable choice for high-end production with “zero chemical reaction + high thermal stability + high process compatibility”. The market share of argon in precision manufacturing will be 78% in 2030 (nitrogen will fall to 15%), driving industrial upgrading and saving quality loss costs of $12 billion per year, according to the Global Industrial Gases Market Report.