A nitrided steel part excellent in pitting resistance and bending fatigue characteristic enabling reduction of size and decrease of weight of parts or enabling demand for high load capacities to be met, using as a material a steel material containing, by mass %, C: 0.05 to 0.25%, Si: 0.05 to 1.5%, Mn: 0.2 to 2.5%, P: 0.025% or less, S: 0.003 to 0.05%, Cr: over 0.5 to 2.0%, Al: 0.01 to 0.05%, and N: 0.003 to 0.025%, having a balance of Fe and impurities, having formed on the steel surface a compound larger of a thickness 3 m or less containing iron, nitrogen, and carbon and a hardened layer formed below the compound layer, and having an effective hardened layer depth of 160 to 410 m.

A nitrided steel part excellent in pitting resistance and bending fatigue characteristic enabling reduction of size and decrease of weight of parts or enabling demand for high load capacities to be met, using as a material a steel material containing, by mass %, C: 0.05 to 0.25%, Si: 0.05 to 1.5%, Mn: 0.2 to 2.5%, P: 0.025% or less, S: 0.003 to 0.05%, Cr: over 0.5 to 2.0%, Al: 0.01 to 0.05%, and N: 0.003 to 0.025%, having a balance of Fe and impurities, having formed on the steel surface a compound larger of a thickness 3 m or less containing iron, nitrogen, and carbon and a hardened layer formed below the compound layer, and having an effective hardened layer depth of 160 to 410 m.

Disclosed is a tempering station for the partial heat treatment of a metal component, the station including a processing plane arranged in the tempering station, at least one nozzle, aligned to the processing plane, for discharging of a fluid flow for the cooling of at least a first sub-area of the component, and at least one nozzle box, arranged above the processing plane. The at least one nozzle box forms at least one nozzle area in which the at least one nozzle is at least partially arrangeable and/or which at least partially delimits a propagation of the fluid flow, with the at least one nozzle box being at least partially formed with a ceramic material. The tempering station permits a sufficiently reliable thermal delimitation of heat treatment measures partially acting on the component and/or a sufficiently reliable thermal separation of different heat treatment procedures partially acting on the component.

The present invention, in consideration of the problems in the prior art, provides a hot stamped body simultaneously achieving the high bendability and high ductility for realizing impact resistance and also hydrogen embrittlement resistance and kept down in scattering in hardness. The hot stamped body according to the present invention is provided with a middle part in sheet thickness and a softened layer arranged at both sides or one side of the middle part in sheet thickness. The middle part in sheet thickness has a hardness of 500Hv to 800Hv and has metal structures from a depth of 20 m below the surface of the softened layer to a depth of of the thickness of the softened layer with an area rate of a total of crystal grains with a maximum crystal orientation difference inside the crystal grains of 1 or less and crystal grains with a maximum crystal orientation difference inside the crystal grains of 8 or more and 15 or less of 50% or more and less than 85%, when a region surrounded by grain boundaries having an orientation difference of 15 or more in a cross-section parallel to the sheet thickness direction is defined as a crystal grain.

The present invention provides a hot stamped body excellent in bendability, ductility, impact resistance, and hydrogen embrittlement resistance and small in scattering in hardness. The hot stamped body according to the present invention is provided with a middle part in sheet thickness and a softened layer arranged at both sides or one side of the middle part in sheet thickness. The middle part in sheet thickness has a hardness of 500 Hv to 800 Hv and has metal structures from a depth of 20 m below the surface of the softened layer to a depth of of the thickness of the softened layer with an area rate of a total of crystal grains with a maximum crystal orientation difference inside the crystal grains of 1 or less and crystal grains with a maximum crystal orientation difference inside the crystal grains of 8 or more and 15 or less of 20% or more and less than 50%, when a region surrounded by grain boundaries having an orientation difference of 15 or more in a cross-section parallel to the sheet thickness direction is defined as a crystal grain.

There is provided a production method for on-line improving precipitation strengthening effect of Ti microalloyed hot-rolled high-strength steel, comprising: casting a molten steel with microalloying element Ti added to obtain an ingot; after heating the ingot, subjecting it to rough rolling, finish rolling, laminar cooling and coiling to obtain a hot-rolled coil; after unloading the coil, covering the coil on-line with an insulating enclosure and moving it into a steel coil warehouse along with a transport chain; after a specified period of on-line insulating time, removing the coil from the insulating enclosure, and cooling it to room temperature in air, wherein the microalloying element Ti has a content of 0.03 wt %; the coiling is performed at a temperature of 500-700 C.; said covering on-line with an insulating enclosure means each hot-rolled coil is individually covered with an independent, closed insulating enclosure unit within 60 minutes after unloading; the on-line insulating time is 60 minutes. The method of the present disclosure is characterized by low cost and high efficiency, and is not affected by surroundings.

The invention is directed to a steel for making a hot working tool, the steel consists of in weight % (wt. %):

TABLE-US-00001 C 0.01-0.08 Si 0.05-0.6 Mn 0.1-0.8 Cr 3.9-6.1 Ni 1.0-3.0 Mo 7.0-9.0 Co 9.0-12.5 Cu 0.2-6.5 N 0.01-0.15 Balance optional elements, impurities and Fe.

The invention is also directed to pre-alloyed powders made from said alloy and AM articles produced from said powder.

A heat-treated steel material is provided having strength of 2.000 GPa or more. The heat-treated steel material includes a chemical composition represented by, in mass %: C: 0.05% to 0.30%; Si: 0.50% to 5.00%; Mn: 2.0% to 10.0%; Cr: 0.01% to 1.00%; Ti: 0.010% to 0.100%; B: 0.0020% to 0.0100%; P: 0.050% or less; S: 0.0500% or less; N: 0.0100% or less; Ni: 0% to 2.0%; each of Cu, Mo, and V: 0% to 1.0%; each of Al and Nb: 0% to 1.00%; and the balance: Fe and impurities. 4612[C]+51[Si]+102[Mn]+605>2000 is satisfied. The heat-treated steel material includes a microstructure in which 90 volume % or more is formed of martensite, and a dislocation density in the martensite is equal to or more than 1.210.sup.16 m.sup.2.

A heat-treated steel material is provided having strength of 2.000 GPa or more. The heat-treated steel material includes a chemical composition represented by, in mass %: C: 0.05% to 0.30%; Si: 0.50% to 5.00%; Mn: 2.0% to 10.0%; Cr: 0.01% to 1.00%; Ti: 0.010% to 0.100%; B: 0.0020% to 0.0100%; P: 0.050% or less; S: 0.0500% or less; N: 0.0100% or less; Ni: 0% to 2.0%; each of Cu, Mo, and V: 0% to 1.0%; each of Al and Nb: 0% to 1.00%; and the balance: Fe and impurities. 4612[C]+51[Si]+102[Mn]+605>2000 is satisfied. The heat-treated steel material includes a microstructure in which 90 volume % or more is formed of martensite, and a dislocation density in the martensite is equal to or more than 1.210.sup.16 m.sup.2.

The present invention improves the strength of the bottom (net) of the jig and makes it more difficult and unlikely for deviation of the mesh to occur. A workpiece is loaded on the net (2) of the heat treat furnace jig (hereinafter, heat treatment furnace jig). In the net (2), a first strand (10), a second strand (20) and a third strand (30) are in contact at a contact point (X1). Near the contact point (X1), the second strand (20) overlaps the first strand (10) from above and the third strand (30) overlaps the first strand (10) from below. As a result, the first strand (10) is held between the second strand (20) and the third strand (30) in the up/down directions.