Self-broaching key

In combination, a self-broaching key and a fastener assembly installed in a threaded passage of a carrier material, said key locking the fastener assembly in the passage and comprising:

• an upper locking portion;
• a lower tang portion formed continuous with said upper locking portion, said lower tang portion including means for frictionally retaining said key within a key slot of the fastener assembly, said means being at least two arcuate surface areas extending at opposite sides of said lower tang portion, said arcuate surface areas being constructed and arranged so as to provide tangential contact between said key and the key slot;
• and
• a cutting surface extending between said upper locking portion and said lower tang portion, said cutting surface defined by a radius and a substantially flat angled surface, wherein the cutting surface is substantially identical to a thread form radius and angled surface of the uppermost thread in the carrier material, and a curvilinear portion immediately adjacent said lower tang portion, said curvilinear portion being constructed to direct carrier material, displaced by said cutting surface, in a direction away from said cutting surface.