Abstract: A self-locking nut has an annular body, an axial threaded bore, and a hexagonal exterior periphery. A small bore is drilled through the body parallel to the threaded bore adjacent to an apex of two peripheral flat surfaces. An L-shaped locking pin has a base leg received in that small bore, and an interference leg projecting into the threaded bore for interfering relation with a mating bolt. The distal end of the base leg is provided with an outwardly facing recess, and this end is secured relative to the nut body by cold flowing body material into engagement with the pin recess. The pin is fabricated from Type 308 stainless steel welding rod having a uniform circular cross section.