SYMPOSIA PAPER Published: 01 January 1998

The New Low Nitrogen Steel LNS — A Material for Advanced Aircraft Engine and Aerospace Bearing Applications


Development tendencies for future aircraft jet engines require new design concepts for rolling element bearings because of an overall increase of loads, temperatures, rotational speeds and the use of new high temperature lubricants.

This paper reviews some of the key parameters which in the past led to the development and application of the known aircraft bearing steels such as M50, M50 NiL and recently Cronidur 30®(AMS 5898). The performance limits of the currently used aerospace bearing steels and the increasing demands on bearing performance for future aerospace applications gave the impact to the design of a new corrosion resistant steel grade of the nitrogen alloyed type, which is suitable for case hardening by nitrogen — the so called “Low nitrogen steel (LNS)”.

The development of the alloy (U.S. pat. 5,503,797), the attainable properties and the corresponding heat treatment process are presented. Achievable hardness, case depth, residual stress pattern and corrosion resistance prove the new “LNS” to be a promising candidate for the next generation of aircraft engine bearings and for advanced, integrated bearing-gear-shaft design concepts.

Author Information

Berns, H
Ruhr-University Bochum, Inst. f. Werkstoffe, Lehrstuhl Werkstofftechnik, Bochum, Germany
Ebert, F-J
FAG Aircraft/Super Precision Bearings GmbH, Schweinfurt, Germany
Zoch, H-W
FAG OEM und Handel AG, Schweinfurt, Germany
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Developed by Committee: A01
Pages: 354–373
DOI: 10.1520/STP12139S
ISBN-EB: 978-0-8031-5381-3
ISBN-13: 978-0-8031-2421-9