- UNS S 31002
- X1 Cr Ni 25.21
- 310L NAG
Austenitic stainless steel with sharp control of the residual elements in order to provide high corrosion resistance properties in boiling 50-65% Nitric acid solutions. The silicon content is kept under 0.3% while the carbon content is lower than 0.015%.
Molybdenum additions are also well known to reduce the behaviour of the steel in nitric acid solutions. This explains why the molybdenum content is guaranteed lower than 0.3% . The sharp control of Carbon, Silicon and phosphorus contents makes it possible to produce a more stable austenite microstructure, free of intermetallic or carbide precipitations. The alloy is designed for nitric acid applications.
- Production of nitric acid,
- Ammonium nitrate production,
- Nuclear fuel reprocessing
- Hydrofluoric pickling.
The grade is not recommended for concentrated nitric acid purposes or highly oxydizing nitric acid solutions (with Cr VI species…)
|Yield strength 0,2% :||283||≥ N/mm²|
|Hardness Brinell:||220||≤ HB|
1100/1150°C (2010/2100°F) followed by rapid cooling.
Because of its high chromium content, 1.4335 has an excellent resistance in boiling nitric acid solutions of less than about 70% concentration.
- Huey tests A262 Practice C – 5 x 48 hours
- Corrosion rate (mm/year)
- Without sensitization : < 0.15 (6 mpy)
- After 1hour at 675°C : < 0.20 (8 mpy)
- After 0.5 hour at 700°C + Slow cooling (50°C/h) : < 0.25 (10 mpy)
Welding The welding of fully austenitic material requires precautions against hot cracking.
- manganese addition in the filler wire,
- low heat input (< 15 KJ/cm)
- controlled welding conditions
- prevention of deformations during welding.
From the corrosion resistance point of view, GTAW/TIG welding is the prefered method and welds in contact with the corrosive solution should preferably be welded using this method.