A finished hex nut made from steel with a maximum carbon content of 0.55%, a minimum manganese content of 0.30%, and a maximum sulphur content of 0.15%. The purchaser and producer of the nuts may agree to allow a sulphur content of 0.33% 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