Wear and galling resistant alloy
Nitronic 601st May 2020
Nitronic® 60 (Fermonic 60, UNS21800) is an austenitic stainless steel with incredibly useful physical properties, specifically wear and galling resistance. It is therefore specified for a number of demanding applications despite possessing more modest corrosion resistance and strength compared with alternative alloys.
Compared with other stainless steels, the composition of Nitronic 60 stands apart due to the significant additions of both manganese and silicon. Whilst manganese is used in other alloys to improve the strength, here it greatly improves the surface properties in combination with silicon. Wear resistance in a number of different settings, against itself, other metals or other materials is very good for a corrosion-resistant alloy. Its galling resistance is also extremely good, in a self-couple or with a dissimilar metal. Galling occurs when two metal surfaces join together, caused by micro-welding across their surfaces. This phenomenon is influenced by the surface condition (roughness), type of metal, environment and temperature. Galling is damage that occurs when breaking the items apart, with a tearing of the surface. Not only can this phenomenon repeat over time, but the debris generated can exacerbate the damage. For components with a degree of repeated movement or sliding, or requiring occasional disassembly, galling would be highly problematic. Therefore, Nitronic 60 is used selectively for valve seats, trim and stems, fasteners, couplings and break-away connectors, pins and bushes.
The general corrosion resistance is between that of Alloy 304 and Alloy 316 stainless steel, whereby is it generally better than Alloy 304 in most environments but superior to Alloy 316 with respect to chloride pitting resistance.
As an austenitic stainless steel, mechanical properties are retained from cryogenic up to elevated temperatures. It, therefore, achieves good impact properties at low temperatures and retention of strength at higher temperatures. Associated with its excellent wear resistance, Nitronic 60 also strongly resists cavitation too.
Nitronic is a registered trademark of AK Steel Corporation and covers a family of functional austenitic stainless steels, including Nitronic 50 (Fermonic 50, XM-19, 1.3964, UNS S20910) which is extremely popular for the production of pump and valve components.