A high-strength screw (2) includes a threaded portion (7) having a thread (8). The screw (2) includes an inner core (16) as seen in cross-section of the screw (2), the core (16) having a first hardness. The screw (2) includes an outer surface layer (17) as seen in cross-section of the screw (2). The screw (2) includes an unhardening layer (18) forming the outer surface layer (17) in the threaded portion (7), the unhardening layer (18) having a second hardness being reduced compared to the first hardness of the core (16).

A mine bolt includes an elongated body having a first end and a second end positioned opposite the first end, with the elongated body having a first threaded section, a second threaded section, and a non-threaded section positioned between the first threaded section and the second threaded section. The non-threaded section is configured to yield under loading when the mine bolt is installed with grout in a bore hole.

Component with a steel part, wherein the steel, among other things, 0.30-0.50 wt. % C, 0.05-1.3 wt. % Mn, 0.001-0.015 wt. % P, 0.001-0.015 wt. % S, 0.01-0.8 wt. % Si, 0.3-1.5 wt. % Cr, 0.005-0.40 wt. % V, 0.0008-0.0050 wt. % B, 0.02-0.35 wt. % Al, 0.0001-0.0200 wt. % N, 0.01-0.08 wt. % Ti, and 0.0030-0.0800 wt. % Zr; comprises the rest iron and unavoidable impurities, wherein the B content in the steel at a depth of 5-60 m is 80% of the B content in the steel at a depth of 500 m.

Disclosed are a heat-resistant alloy used in a heat-resistant bolt and the like for fastening high temperature parts of an engine in a vehicle and the like, and a method of manufacturing a heat-resistant bolt using the heat-resistant alloy. Particularly, the austenitic heat-resistant alloy includes, based on a total weight of the heat-resistant alloy, carbon (C) in an amount of about 0.01 to about 0.08 wt %, silicon (Si) in an amount of about 0.01 to about 1.00 wt %, manganese (Mn) in an amount of about 0.01 to about 2.00 wt %, nickel (Ni) in an amount of about 17 to about 22 wt %, titanium (Ti) in an amount of about 2.7 to about 3.2 wt %, chromium (Cr) in an amount of about 11 to 16 wt %, molybdenum (Mo) in an amount of about 0.3 to about 1.0 wt %, vanadium (V) in an amount of about 0.1 to about 0.4 wt %, and a remainder of iron (Fe) and optionally an inevitable impurity.

A hollow screw and related process of making is provided, wherein the hollow screw is formed from a generally circular corrosion resistant stainless steel disk cut from flat roll stock. The hollow screw includes a head and an elongated and hollow shaft having a wall thickness between about 0.2 to about 0.7 millimeters extending therefrom and defining a shank portion and a threaded portion having a plurality of threads thereon with a rotational drive mechanism configured to facilitate tightening via the threads. The process involves annealing to soften the stamped hollow screw, followed by thread rolling, and then age hardening the hollow screw. As such, the resultant hollow screw is relatively lightweight, about 50% the mass of a solid core screw made from the same material, with a sufficient thread strength to meet most aerospace applications and contributes to important aircraft fuel economy.

The present disclosure relates to methods for manufacturing a wire rod for cold forging and a screw part, which may manufacture with only quenching heat treatment a part with excellent drilling characteristics, and which may specifically manufacture a part to be used for mechanical coupling of automotive parts manufactured with different materials.

A steel is used for providing a bolt that has a high strength and still exhibits excellent hydrogen embrittlement resistance. The steel contains C of 0.30% to 0.50%, Si of 1.0% to 2.5%, Mn of 0.1% to 1.5%, P of greater than 0% to 0.015%, S of greater than 0% to 0.015%, Cr of 0.15% to 2.4%, Al of 0.010% to 0.10%, N of 0.001% to 0.10%, Cu of 0.1% to 0.50%, Ni of 0.1% to 1.0%, Ti of 0.05% to 0.2%, and V of 0% to 0.2%, with the remainder including iron and inevitable impurities, in which a ratio [Ni]/[Cu] is 0.5 or more, and a total content [Ti]+[V] is 0.085% to 0.30%.

A hollow screw and related process of making is provided, wherein the hollow screw is formed from a generally circular corrosion resistant stainless steel disk cut from flat roll stock. The hollow screw includes a head and an elongated and hollow shaft having a wall thickness between about 0.2 to about 0.7 millimeters extending therefrom and defining a shank portion and a threaded portion having a plurality of threads thereon with a rotational drive mechanism configured to facilitate tightening via the threads. The process involves annealing to soften the stamped hollow screw, followed by thread rolling, and then age hardening the hollow screw. As such, the resultant hollow screw is relatively lightweight, about 50% the mass of a solid core screw made from the same material, with a sufficient thread strength to meet most aerospace applications and contributes to important aircraft fuel economy.

Provided are a high-strength bolt having a tensile strength of 1,000 to 1,400 MPa and exhibits the same level of the delayed fracture resistance as that of the standard alloy steel even when omitting or reducing Mo and Cr from the SCM steel and the SCr steel, a steel wire for bolts used to manufacture such a high-strength bolt, and useful methods for manufacturing them. The steel wire for bolts in the present invention satisfies the predetermined chemical composition. When a rate of a B content at D.sub.0/4 part in the steel wire for bolts is 100% where D.sub.0 is a diameter of the steel wire for bolts, a ratio of a B content at a surface of the steel wire for bolts is 75% or less on average, and a difference between a maximum value and a minimum value of the ratio is 25% or less. A prior austenite crystal grain size number in a region from the surface to a depth of 100 m of the steel wire for bolts is No. 8 or more.

Component with a component (1) made of steel, wherein the component is at least partially coated with a nickel diffusion layer (10), and the layer thickness of the nickel diffusion layer (10) is 1-500 m and the nickel diffusion layer (10) has a nickel content, based on the total weight of the nickel diffusion layer, of 2 wt. % above the nickel content of the steel up to a maximum concentration, the nickel content in the nickel diffusion layer (10) increasing continuously in the direction of the surface (12) of the nickel diffusion layer (10) from 2% by weight up to the maximum concentration and the maximum concentration being 20-100% by weight.