Method of making threaded fasteners.

摘要

A threaded fastener has an external thread form (13) and a shank portion (12). The shank portion (12) has at least one substantially circumferential groove (15) the depth of which is such that the effective stress area thereby produced is less than the minimum effective stress area of the external thread form and is also such that yield of the threaded fastener occurs in use in the region of the or each groove (15) at a predetermined load. The depth of the or each groove (15) may be such that the diameter of the shank portion (12) at the base of the or each groove is in accordance with the relationship: <MATH> where D is the diameter at the base of the or each groove (m) sigma is the tensile strength of the wire (N/m<2>) F is the load (N) required to produce yielding of the fastener in the region of the or each groove K is a constant. f