Abstract: A locknut comprising a metal nut including a threaded internal wall for engaging a threaded shaft; and a metal ring including an internal threaded wall defining a hole for engaging the threaded shaft. The ring comprised of a steel alloy. The threaded internal wall of the nut and the threaded internal wall of the ring being in general axial alignment when the ring is received by a bore of the nut. The ring has an elliptical configuration and is configured to distort to a circular configuration when the threaded shaft is engaged with the threaded internal wall of the nut and the threaded internal wall of the ring. The ring sized such that the stress in the ring when the ring is distorted to the generally circular configuration is less than the yield stress of the steel alloy. A thermal diffusion coating may be applied to the ring.