A steel wire for high-strength bolts is used for a non heat-treatment bolt with an excellent cold forgeability for which quenching and tempering steps have been omitted after bolt formation, and which has a tensile strength of 1200 MPa or more and an excellent delayed fracture resistance. The steel wire includes C, Si, Mn, P, S, Cr, Al, N, and B, at least one selected from the group consisting of Ti, V, and Nb with the balance consisting of iron and inevitable impurities. The steel wire has a microstructure wherein ferrite and perlite have a total area rate of 98% or more, perlite lamellar spacing is 250 nm or less, and an area rate of the perlite is more than 40%, and 80% or less. The steel wire has a tensile strength of 1300 MPa or less.

A union screw (1) for pipes (2) provided with at least one flare (21) comprises a metal base body (10) which accommodates the pipe (20). The union screw (1) further comprises a screw head (12), a threaded portion (13), a contact portion (15) which is configured to abut the flare (21) of the pipe (20), and a functional layer (40) with which the base body (10) is coated at least in the region of the threaded portion (13) and the contact portion (15). The functional layer (40) is multi-layered and consists of at least one base coat (41) and a top coat (42) applied to the base coat (41) at least in some areas. The base coat (41) forms a structure for creating corrosion protection and a far-reaching invariance with regard to the material of the usual friction partners of the union screw (1) which, in addition to a binder, also contains zinc in the form of zinc-containing lamellae (43), which are oriented to lie substantially flat on the base body (10).

A union screw (1) for pipes (2) provided with at least one flare (21) comprises a metal base body (10) which accommodates the pipe (20). The union screw (1) further comprises a screw head (12), a threaded portion (13), a contact portion (15) which is configured to abut the flare (21) of the pipe (20), and a functional layer (40) with which the base body (10) is coated at least in the region of the threaded portion (13) and the contact portion (15). The functional layer (40) is multi-layered and consists of at least one base coat (41) and a top coat (42) applied to the base coat (41) at least in some areas. The base coat (41) forms a structure for creating corrosion protection and a far-reaching invariance with regard to the material of the usual friction partners of the union screw (1) which, in addition to a binder, also contains zinc in the form of zinc-containing lamellae (43), which are oriented to lie substantially flat on the base body (10).

An electrically contacting fastening device has a threaded bolt and a nut, between which an electric contact element can be arranged. The threaded bolt has a contacting portion for creating planar contact with the contact element, and a threaded portion. The nut can be secured on the threaded bolt by way of the threaded portion and at an end face has a contacting area for creating planar contact with the contact element. The threaded portion of the threaded bolt is provided with a lubricant coating and the contacting portion of the threaded bolt, the contact element and the end-face contacting area of the nut are permanently free of lubricant.

An electrically contacting fastening device has a threaded bolt and a nut, between which an electric contact element can be arranged. The threaded bolt has a contacting portion for creating planar contact with the contact element, and a threaded portion. The nut can be secured on the threaded bolt by way of the threaded portion and at an end face has a contacting area for creating planar contact with the contact element. The threaded portion of the threaded bolt is provided with a lubricant coating and the contacting portion of the threaded bolt, the contact element and the end-face contacting area of the nut are permanently free of lubricant.

The invention relates to a metallic fastener (10; 40) for the interference fit assembly of at least two structural elements (20, 22) comprising a through hole, the fastener comprising an enlarged head (12; 42), a shaft (14; 44) having an external diameter before installation that is greater than an internal diameter of the hole, said shaft comprising a conductive surface (26; 56). Before installation, at least the conductive surface (26; 56) is coated with a lubricating layer (30), which comprises a mixture of at least one polyolefin and one polytetrafluoroethylene, for example, having sufficient adherence to prevent its abrasion by manual manipulation of the fastener and being weak enough to be at least partly stripped from the conductive surface during the interference fit assembly of the fastener.

The invention further relates to a method for obtaining such a fastener and to a method for installing such a fastener in a structure.

The invention is applicable to the assembly of aircraft structures.

The invention relates to a metallic fastener (10; 40) for the interference fit assembly of at least two structural elements (20, 22) comprising a through hole, the fastener comprising an enlarged head (12; 42), a shaft (14; 44) having an external diameter before installation that is greater than an internal diameter of the hole, said shaft comprising a conductive surface (26; 56). Before installation, at least the conductive surface (26; 56) is coated with a lubricating layer (30), which comprises a mixture of at least one polyolefin and one polytetrafluoroethylene, for example, having sufficient adherence to prevent its abrasion by manual manipulation of the fastener and being weak enough to be at least partly stripped from the conductive surface during the interference fit assembly of the fastener.

The invention further relates to a method for obtaining such a fastener and to a method for installing such a fastener in a structure.

The invention is applicable to the assembly of aircraft structures.

Steel for a high-strength bolt contains: from 0.50 mass % to 0.65 mass % carbon, from 1.5 mass % to 2.5 mass % silicon, 1.0 mass % or more chromium, 0.4 mass % or less manganese, greater than 1.5 mass % molybdenum, 0.03 mass % or less phosphorus and sulfur combined, and balance iron and inevitable impurities.

A high-strength bolt is formed using steel for a high-strength bolt that contains: from 0.50 mass % to 0.65 mass % carbon, from 1.5 mass % to 2.5 mass % silicon, 1.0 mass % or more chromium, 0.4 mass % or less manganese, greater than 1.5 mass % molybdenum, 0.03 mass % or less phosphorus and sulfur combined, and balance iron and inevitable impurities.

A fastener includes an elongated shaft having a first end, a second end, and a shaft body, a head portion, and a threaded portion. At least one inner feed channel extends through the head portion and the shaft body and terminates proximal to the threaded portion. The fastener has a plurality of flutes formed along and circumferentially spaced around an outer surface of the shaft body and an outer surface of the head portion. Each flute has a first end and extends from a first location proximal to the threaded portion, along the outer surface of the shaft body, and radially outward along the outer surface of the head portion. The fastener further has one or more lateral feed channels formed laterally through the shaft body and connecting the inner feed channel to at least two opposing flutes on the outer surface of the shaft body.

Fasteners are inserted into a stack of members and terminated with parts having at least one of a dry dielectric coating and a dry dielectric seal at select locations to protect against electromagnetic effects (EME).