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 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. The grade is not recommended for concentrated nitric acid purposes or highly oxydizing nitric acid solutions (with Cr VI species...)