| 摘要 |
A high strength screw in which a high strength steel material is employed and which, by the administering of a carburization hardening process on the surface thereof, has high tensile stress and shear stress, high surface hardness, and, particularly in tapping screws, good male thread formability with respect to the foundation hole of the opposing member, and very good tightening and joining properties and durability. Compatibility with a machine screw is provided in such a way that, once the tapping screw has been removed from the opposing member, a machine screw can be screwed into the male thread formed by the tapping screw. A screw is formed from a material which comprises a high tensile steel, and a surface hardening process, in particular a continuous quenching gas carburization process, is performed on, at least, the thread part to form a surface hardened layer of a depth in the range of 0.05 to 0.3mm. <IMAGE> |
