A finished, heat treated hex nut made from steel with maximum carbon content of 0.55%, minimum manganese content of 0.30%, and a maximum sulfur content of 0.05% (standard Grade 8 hex nut). The manufacturer of the nuts may agree to allow a sulfur content of .33% maximum provided that the manganese content is at least 1.35%. For use with bolts with a minimum tensile strength equal to or less than 150,000 PSI. HN516C8