1.4335 – 310L NAG – S31002 – 2RE10
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310L NAG / UR™ 65 is a 25 Cr 20 Ni 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 behavior 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. The grade is not recommended for concentrated nitric acid purposes or highly oxidizing nitric acid solutions (with Cr VI species...).
|> EURONORM :||EN 1.4435||X1 Cr Ni 25-21|
|> ASTM :||310L NAG|
Because of its high chromium content, UR™ 65 has an excellent resistance in boiling nitric acid solutions of less than about 70% concentration. In these conditions, the alloy behaves much better than 304 L grade.
Moreover, thanks to the close control of impurities such as carbon, silicon, phosphorus which are known to be deleterious to the resistance of stainless steels in nitric acid solutions in the sensitized condition, UR™ 65 grade performs very well in HNO3 solution up to 70%.
Nitric acid solutions containing CrVI species are much more oxydant than usual HNO3 solutions.
In those cases, UR™ 65 is normally not to be used. UR™ 65 melts are optimized to improve corrosion resistance in nitric acid solutions, even after welding.
UR™ 65 is used in all processes involving hot nitric acid up to 70% concentration (14 N) (solutions free of CrVI species or other very oxydizing species) :
⦁ Production of nitric acid
⦁ Ammonium nitrate production
⦁ Nuclear fuel reprocessing
⦁ Hydrofluoric pickling