HIGH TENSILE BOLT, NUT, AND WASHER

摘要

PROBLEM TO BE SOLVED: To provide a set of a high tensile bolt, a nut and a washer which is excellent in delayed fracture resistance and fatigue resistance by far more reducing stress concentration generated at a thread bottom of an engaging end than any other preceding technology. SOLUTION: The high tensile bolt 10 is provided with a screw thread 16, in which a pressurized flank face 12 on the side on which the load acts, and a non-pressurized flank face 14 on the side on which the load does not act, are a symmetry of right and left, and, a vertical sectional shape of the screw bottom 18 connecting the pressurized flank face 12 and the non-pressurized flank face 14 is formed by a higher-order curve 20 drawing a slow curve which is in contact with a flank line of the pressurized flank face 12 and an arc 22 which is in contact with the higher-order curve 20 and the flank line of the non-pressurized flank face 14.