The disclosure relates to a process for the manufacture of a steel component comprising a fine-grained martensite structure component. The process comprises the steps of providing a steel component having an initial steel composition; introducing nitrogen into the steel component at a temperature T1 above 950? C., thereby creating an at least partly austenitic nitrogen-containing steel component; bringing the at least partly austenitic nitrogen-containing steel component to a temperature T2, such that austenite is decomposed into a steel component comprising at least an amount of carbon- and/or nitrogen-containing precipitates; bringing the steel component comprising at least an amount of carbon- and/or nitrogen-containing precipitates to a temperature T3 which is above T2, thereby creating an at least partly austenitic nitrogen-containing steel component optionally comprising at least an amount of carbon- and/or nitrogen-containing precipitates; and bringing the at least partly austenitic nitrogen-containing steel component to a temperature T4 that is below a martensite start temperature of the at least partly austenitic nitrogen-containing steel component for initiating transformation of at least some of the austenite into fine-grained martensite, thereby producing a steel component comprising a fine-grained martensite structure component.

Disclosed is a martensitic stainless steel with improved strength and corrosion resistance. The disclosed martensitic stainless steel sheet comprises, in percent by weight (wt %), 0.3 to 0.5% of C, 0.01 to 0.025% of N, 0.3 to 0.5% of Si, 0.4 to 0.6 of Mn, 13.1 to 14.5% of Cr, 0.95 to 1.10% of Mo, 0.05 to 0.3% of V, 0.3 to 0.5% of Ni, 0.001 to 0.5% of Cu, and the balance being Fe and inevitable impurities, and satisfies Formula (1). Formula (1): 16.4?(Cr+3.3Mo+16N)*(Mo+V)?23.3, wherein Cr, N, Mo, and V denote the contents (wt %) of respective elements.

This joint component includes: a first steel member; a second steel member; and a joint portion which is formed at butted portions between the first steel member and the second steel member and includes a weld metal and a heat-affected zone, in which the first steel member includes a steel sheet substrate and an AlFe-based coating formed on a surface of the steel sheet substrate, and has a tensile strength of more than 1,500 MPa, and when a cross section of the weld metal in a sheet thickness direction orthogonal to an extension direction of the joint portion is defined as a measuring surface, an average Cu content in the weld metal at the measuring surface is 0.03% or more and 3.00% or less by mass %.

An object of the present invention is to provide a ball screw having a structure in which a screw shaft and a nut satisfy required performance and having improved durability, a method for manufacturing the ball screw, a power steering device, and a method for manufacturing the power steering device. A ball screw according to the present invention includes: a nut made of a steel substrate having an inner peripheral surface on which a female screw is formed; a screw shaft that is combined with the nut and is made of a steel substrate having an outer peripheral surface on which a male screw facing the female screw is formed; and a plurality of balls arranged between the female screw and the male screw. A surface of the nut in contact with the ball and a surface of the screw shaft in contact with the ball each have carburized layers. A carbon concentration in the carburized layer of the nut is higher than a carbon concentration in the carburized layer of the screw shaft.

An apparatus for manufacturing a rack bar includes a pre-forming machine forming a flattened portion on an outer peripheral surface of a hollow shaft member, a teeth forming machine forming rack teeth on the flattened portion, a heat treatment machine quenching the rack teeth, a first conveying machine carrying the shaft member into and from the pre-forming machine, a second conveying machine carrying the shaft member into and from the teeth forming machine, and a third conveying machine carrying the shaft member into and from the heat treatment machine. The first conveying machine, the second conveying machine, and the third conveying machine hold one end of the shaft member from a radially inner side of the shaft member. The apparatus of the rack bar are suitable for manufacturing a relatively short hollow rack bar having rack teeth formed over substantially an entire length of a shaft member.

A steel sheet for hot stamping includes: a steel sheet having a predetermined chemical composition; and a plating layer provided on a surface of the steel sheet, the plating layer having an adhesion amount of 10 g/m.sup.2 to 90 g/m.sup.2 and a Ni content of 10 mass % to 25 mass %, and containing a remainder consisting of Zn and impurities. The steel sheet for hot stamping includes, in a surface layer region of the steel sheet, 80% or more by area % of grains having an average crystal orientation difference of 0.4? to 3.0? inside grains surrounded by grain boundaries having an average crystal orientation difference of 5? or more.

The steel material according to the present disclosure has a chemical composition consisting of, in mass %, C: 0.15 to 0.45%, Si: 0.05 to 1.00%, Mn: 0.01 to 1.00%, P: 0.030% or less, S: 0.0050% or less, Al: 0.005 to 0.100%, Cr 0.60 to 1.80%, Mo: 0.80 to 2.30%, Ti: 0.002 to 0.020%, V: 0.05 to 0.30%, Nb: 0.002 to 0.100%, B: 0.0005 to 0.0040%, Cu: 0.01 to 0.50%, Ni: 0.01 to 0.50%, N: 0.0020 to 0.0100% and O: 0.0020% or less, with the balance being Fe and impurities. The number density of BN in the steel material is 10 to 100 particles/100 ?m.sup.2. The yield strength of the steel material is 758 MPa or more.

The invention relates to a method for producing a chassis part from micro-alloyed steel, having an improved cold workability of cold-solidified, mechanically separated sheet-metal edges, comprising the following method steps: providing a hot-rolled strip or a hot-rolled strip sheet of the claimed alloy composition in weight percent, cutting a blank at room temperature and optionally carrying out further punching or cutting operations, heating exclusively the sheet metal edge regions of the blank, which have been cold-solidified by the cutting or punching operations, to a temperature of at least 700? C. with a dwell time of at most 10 seconds and subsequent cooling with air, cold forming the blank in one or more steps to form a chassis part at room temperature.

Disclosed embodiments include fuel assemblies, fuel element, cladding material, methods of making a fuel element, and methods of using same.

A method of manufacturing a hydraulic hammer using a male gauge and a female gauge is provided wherein the hammer comprises a body and a chuck housing that are connectable by cooperatively formed thread fittings. A cooperatively threaded male gauge and female gauge can be used to form the threads on the body and the chuck housing and to determine the rotational orientation of the body and the chuck housing relative to one another. One of the gauges can be used to measure distortion of the chuck housing caused by heat treatment subsequent to the formation of the thread fitting and thereby to determine the required subsequent machining of the chuck housing necessary to retain the appropriate relative rotational orientation when the chuck housing is connected to the body. The method can comprise the steps of making and appropriately marking the male gauge and the female gauge.