A self-locking nut includes a main-nut body and a deformable-nut body. The main-nut body has a recess leading into an interior threaded bore forming x turns of an internal thread therein. The deformable-nut body has an outer flange and an interior threaded bore forming y turns of an internal thread therein. The outer flange of the deformable-nut body is fixed to the main-nut body such that a relief space is formed between the deformable-nut body and the recess. A ratio of x:y is about 2:1.