FAG has recently introduced a new group of corrosion resisting bearing steels in which the carbon is mostly replaced by nitrogen. They have been developed in Germany under a joint research partnership involving Ruhr Universtat-Bochum LWT), Institut fur Werkstofftechnik, Bremen, and Vereinigte Schmiedewerke, Essen. Currently, there are two grades: high nitrogen steel, which is martensitic through-hardened or inductive case- hardened and low nitrogen steel (LNS) which is case hardened with nitrogen. However, FAG’s industrial sales manager, Lex Browning told Design Engineering that the high cost of the steel is likely to restrict its use to very high-value applications such as those within the aerospace market.
To date, these have included: a fuel pump bearing within the space shuttle main engine which is used for about 20 flights without the need for replacement: part of a flap actuator on the Boeing B777, a bearing on the
Eurocopter NH90 and sundry bearings used on Boeing airframes. They have also been used on pumps for water-based fluids.
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