What is the difference between Nitronic 50 and Nitronic 60?

Nitronic 50 and Nitronic 60 are both austenitic stainless steels but provide very different levels of mechanical and physical properties. Nitronic is a trademark of AK Steel Corporation and is applied to a range of stainless steel grades that utilised nitrogen as an alloying element.

Nitronic 50 (Nit50, UNS S20910, DIN 1.3964, ASTM A182 XM19) is widely used in applications such as valve bodies and stems. It provides almost double the yield strength of common austenitic stainless steel grades such as Alloy 304 and Alloy 316L yet maintains excellent ductility and toughness at both elevated and cryogenic temperatures. The Pitting Resistance Equivalent number (PREN) is above 34 for Nitronic 50, which is comparable with a duplex stainless steel such as S32205, and far better than a regular Alloy 316L grade that achieves 25. Nitronic 50 has been identified as an alloy suitable for hydrogen service and is also listed in NACE MR 01 75 for sour service given its ability to resist sulphide stress cracking.

Nitronic 50 can be provided in several different conditions. In the annealed condition it is relatively low strength, but far easier to machine into more complex components. However, the more popular condition is ‘High Strength’, also referred to as ‘Warm Worked’ or ‘Hot Rolled’.

Nitronic 60 (UNS S21800) shares the same trademark but is a specialist alloy used when resistance to galling is a critical requirement. The term galling is when two metal surfaces join unintentionally, caused by micro-welding across their surfaces at localised points of contact. Galling typically refers to the damage that occurs when breaking the items apart, with a tearing of the surface. It is more likely to occur when components are left in intimate contact for extended periods, typically under load. Therefore, resistance to galling is an important requirement for components such as couplings, connectors, stab plates and dry break couplings which may remain connected for very long periods but need to disconnect quickly. Nitronic 60 is heavily alloyed with silicon and manganese which provide that resistance to galling.

Langley Alloys carries stock of Nit50 in both Annealed and High Strength condition as solid round bars up to 10” (254mm diameter). Nit 60 is stocked in a range of sizes to suit the most common applications.


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