A workpiece for a fuel injection component is made of a steel having compositions, by mass %, of C: 0.08 to 0.16%, Si: 0.10 to 0.30%, Mn: 1.00 to 2.00%, S: 0.005 to 0.030%, Cu: 0.01 to 0.30%, Ni: 0.40 to 1.50%, Cr: 0.50 to 1.50%, Mo: 0.30 to 0.70%, V: 0.10 to 0.40%, s-Al: 0.001 to 0.100%, and Fe and unavoidable impurities as remaining components. After heating the workpiece to a temperature of 950 C. or more and 1350 C. or less, the workpiece is subjected to a hot forging, and thereafter cooled at an average cooling rate of 0.1 C./sec. or more in a temperature range from 800 C. to 500 C., and at the average cooling rate of 0.02 C./sec. or more and 10 C./sec. or less in the subsequent temperature range from 500 C. to 300 C. to set an area ratio of a bainite structure after hot forging to 85% or more.

A valve is provided, in particular an injection valve, having a valve seat and a valve needle which extends along a closing direction for the most part, the valve seat having a valve-seat surface, and a valve-closing element is mounted on an end of the valve needle facing the valve seat, the valve-closing element being able to be moved between an open position and a closed position, and the valve-closing element together with the valve-seat surface forming a sealing seat in the closed position, the valve-closing element having a greater core hardness and/or surface hardness than the valve-seat surface.

A fuel injector and a nozzle for a fuel injector is provided. The nozzle includes at least one spray hole that is formed through a hardened nozzle body. The nozzle body is hardened again after forming the at least one spray hole to hardened the nozzle body along the at least one spray hole.

A first member has a plated layer. A second member is pressed against the plated layer and causes a tensile stress in the first member. A breakage probability is a probability of breakage of the plated layer caused by the tensile stress. A characteristic line represents a relationship between an elastic modulus of the plated layer and the breakage probability. A characteristic slope of the characteristic line is a ratio of an increase in the breakage probability to a decrease in the elastic modulus. A characteristic change point appears on the characteristic line at which the elastic slope increases to exceed a predetermined slope as the elastic modulus gradually decreases. A characteristic change elastic modulus is the elastic modulus at the characteristic change point. The plated layer contains at least a chromium component and has the elastic modulus larger than the characteristic change elastic modulus.

A valve is provided, in particular an injection valve, having a valve seat and a valve needle which extends along a closing direction for the most part, the valve seat having a valve-seat surface, and a valve-closing element is mounted on an end of the valve needle facing the valve seat, the valve-closing element being able to be moved between an open position and a closed position, and the valve-closing element together with the valve-seat surface forming a sealing seat in the closed position, the valve-closing element having a greater core hardness and/or surface hardness than the valve-seat surface.

An electromagnetically actuable rate control valve for controlling a delivery rate of a high-pressure pump includes an electromagnet, a valve element, an armature shaft, and at least one strength element. The valve element is movable in an axial direction and is configured to open and to close the electromagnetically actuable rate control valve. The armature shaft transmits a force. The force is produced by the electromagnet and acts on the valve element in the axial direction. The at least one strength element is configured to raise at least the strength of the armature shaft. The armature shaft includes a needle region adjacent to the valve element and an armature region remote from the valve element. The needle region and the armature region are integral with each other.

A fuel injection valve includes a body that includes an injection hole through which fuel is injected, and a valve element that opens or closes the injection hole. The body includes a metallic base material configured to form the injection hole, a corrosion-resistant layer covering a surface of at least a part of the base material that forms the injection hole and being made of a less corrosive material than the base material, and a diffusion deterring layer located between the base material and the corrosion-resistant layer and made of a material that less easily allows a metal component of the base material to diffuse than the material of the corrosion-resistant layer.

A steel pipe has a composition consisting, by mass percent, of, C: 0.12 to 0.27%, Si: 0.05 to 0.40%, Mn: 0.3 to 2.0%, Al: 0.005 to 0.060%, N: 0.0020 to 0.0080%, Ti: 0.005 to 0.015%, Nb: 0.015 to 0.045%, Cr 0 to 1.0%, Mo: 0 to 1.0%, Cu: 0 to 0.5%, Ni: 0 to 0.5%, V: 0 to 0.15%, and B: 0 to 0.005%, the balance being Fe and impurities. As impurities, contents are Ca: 0.001% or less, P: 0.02% or less, S: 0.01% or less, and O: 0.0040% or less. The micro-structure is tempered martensitic or tempered martensite and tempered bainite, in which a prior-austenite grain size number is 10.0 or more. Tensile strength is TS 800 MPa or higher. Critical internal pressure is [0.3TSa] or more, a=[(D/d).sup.2?1]/[0.776(D/d).sup.2], D: pipe outer diameter (mm), d: pipe inner diameter (mm).

A valve for metering fluid has an electromagnet for actuating a valve needle controlling a metering opening. The electromagnet generates, upon current flow, a magnetic flux that proceeds via an outer pole, a hollow-cylindrical inner pole, an armature displaceable on an armature guidance region embodied on the valve needle, and a working air gap delimited by the armature and inner pole. Disposed fixedly on the valve needle is an entraining element that penetrates axially displaceably into an entraining element guidance region embodied in the inner pole and has a radial stop shoulder for the armature which delimits a take-up travel or pre-stroke travel. The entraining element is extended into an additional inner pole having a pole surface formed by the stop shoulder, and is embodied magnetically conductively and a magnetic flux between the armature and valve needle is suppressed by way of a magnetically nonconductive material.

A fuel injector and a nozzle for a fuel injector is provided. The nozzle includes at least one spray hole that is formed through a hardened nozzle body. The nozzle body is hardened again after forming the at least one spray hole to hardened the nozzle body along the at least one spray hole.