Provided is a heat treatment apparatus (1), including: a conveying device (10), which is configured to convey a rod-shaped workpiece (W) at a predetermined velocity along an axial direction of the workpiece (W); and a heating device (2) including a heating coil (3) configured to inductively heat the workpiece (W) being conveyed to a quenching temperature, wherein the heating coil (3) includes a first heating section (3A) and a second heating section (3B), which are coupled to each other in series along the axial direction of the workpiece (W), and is electrically connected to a single high-frequency power supply (4), and wherein a coil pitch (D2) of the second heating section (3B) arranged relatively on a front side in a conveying direction for the workpiece (W) is larger than a coil pitch (D1) of the first heating section (3A) arranged relatively on a rear side in the conveying direction.

Provided is a heat treatment apparatus (1), including: a conveying device (10), which is configured to convey a rod-shaped workpiece (W) at a predetermined velocity along an axial direction of the workpiece (W); and a heating device (2) including a heating coil (3) configured to inductively heat the workpiece (W) being conveyed to a quenching temperature, wherein the heating coil (3) includes a first heating section (3A) and a second heating section (3B), which are coupled to each other in series along the axial direction of the workpiece (W), and is electrically connected to a single high-frequency power supply (4), and wherein a coil pitch (D2) of the second heating section (3B) arranged relatively on a front side in a conveying direction for the workpiece (W) is larger than a coil pitch (D1) of the first heating section (3A) arranged relatively on a rear side in the conveying direction.

A copper-zinc alloy having the following composition (in % by weight): from 67.0 to 69.0% of Cu, from 0.4 to 0.6% of Si, from 1.2 to 1.6% of Mn, from 0.03 to 0.06% of P, optionally up to a maximum of 0.5% of Al, optionally up to a maximum of 0.15% of Ni, optionally up to a maximum of 0.1% of Fe, optionally up to a maximum of 0.1% of Pb, optionally up to a maximum of 0.08% of Sn, optionally up to a maximum of 0.1% of S,
balance Zn and unavoidable impurities. The alloy has a microstructure which consists of an -phase matrix in which inclusions of manganese silicides having a globular shape are present in a proportion of at least 2% by volume and not more than 5% by volume.

The invention relates to a duplex stainless steel composition, the composition of which consists of, in % by weight: C0.05% 21%Cr25% 1%Ni2.95% 0.16%N0.28% Mn2.0% Mo+W/20.50% Mo0.45% W0.15% Si1.4% Al0.05% 0.11%Cu0.50% S0.010% P0.040% Co0.5% REM0.1% V0.5% Ti0.1% Nb0.3% Mg0.1% the balance being iron and impurities resulting from the smelting, and the microstructure consisting of austenite and 35 to 65% ferrite by volume, the composition furthermore satisfying the following relationships:

40I.sub.F70

where

I.sub.F=6(% Cr+1.32% Mo+1.27% Si)10(% Ni+24% C+16.15% N+0.5% Cu+0.4% Mn)6.17

and

I.sub.LCR30.5

where

I.sub.LCR=% Cr+3.3% Mo+16% N+2.6% Ni0.7% Mn, and also to a process for manufacturing plate, strip, coil, bar, rod, wire, sections, forgings and castings made of this steel.

Disclosed is a method for producing a steel part, which includes the steps of: preparing a built-up steel sheet including a steel sheet 20 including: C: 0.15 to 0.5% by mass, Si: 0.10 to 3% by mass, Mn: 0.5 to 5% by mass, P: 0.05% by mass or less (excluding 0%), S: 0.05% by mass or less (excluding 0%), Al: 0.01 to 1% by mass, B: 0.0002 to 0.01% by mass, Ti: 0.005 to (3.4[N]+0.1) % by mass (in which [N] represents a content of N (% by mass)), and N: 0.001 to 0.01% by mass, with the balance being iron and inevitable impurities, and one or more built-up portions 30 provided on the steel sheet 20; hot-forming the built-up steel sheet at a temperature of an Ac3 point or higher of the steel sheet 20; and cooling the hot-formed built-up steel sheet to a temperature of an Ms point or lower of the steel sheet such that an area ratio of martensite in the metal structure of the steel sheet 20 is 70% or more.

A steel sheet used for hot stamping includes, by weight percent, 0.180.42% of C, 48.5% of Mn and 0.83.0% of Si+Al with the balance being Fe and unavoidable impurities. The alloy elements of the steel sheet enable the actual measured value of the martensitic transformation start temperature after hot stamping to be 280 C. The method for manufacturing the component includes: heating the material to 700850 C. and then stamping; cooling it to the temperature that is 150260 C. below the martensitic transformation start temperature by cooling in a die, cooling by air, water, or other methods; heating the component to a temperature ranging from 160 to 450 C. and maintaining the temperature for 1 to 100000 seconds for heat treatment, and then cooling the component to room temperature. The formed component has a yield strength of 1200 MPa, a tensile strength of 1600 MPa and a total elongation of 10%.

A steel alloy is disclosed that provides a unique combination of strength, toughness, and fatigue life. The steel alloy has the following composition in weight percent:

TABLE-US-00001 C about 0.15 to about 0.30 Mn about 1.7 to about 2.3 Si about 0.7 to about 1.1 Cr about 1.85 to about 2.35 Ni about 0.5 to about 0.9 Mo + W about 0.1 to about 0.3 Cu about 0.3 to about 0.7 V + 5/9 Nb about 0.2 to about 0.5
The balance of the alloy is iron, usual impurities, and residual amounts of other elements added during melting for deoxidizing and/or desulfurizing the alloy. A hardened and tempered steel article made from the alloy is also disclosed.

A manufacturing method of a steel component includes: heating a steel sheet in a carburizing atmosphere to form a carburized layer on a surface of the steel sheet, the steel sheet having: a chemical composition represented by: in mass %, C: 0.0005 to 0.1%; Si: 0.01 to 2.0%; Mn: 0.05 to 3.0%; Al: 0.9% or less; P: 0.05% or less; S: 0.01% or less; Ti: 0.0 to 0.2%; Nb: 0.0 to 0.1%; Cr: 0 to 2%; Mo: 0.0 to 0.2%; B: 0.000 to 0.005%; and the balance: Fe and impurities; and a steel structure represented by ferrite with an area fraction of 70% or more; and forming the steel sheet by using metal dies, and performing quenching on the steel sheet in a state of housing the steel sheet in the metal dies to transform the carburized layer into martensite and make a part of the steel sheet on the further inside than the carburized layer to be a steel structure represented by ferrite with an area fraction of 50% or more.

A method for manufacturing a nonlinear superelastic file comprising the steps of: providing a superelastic file having a shaft and a file axis; providing a fixture including a file groove being defined by one or more displacement members, the file groove configured for receiving the shaft; inserting at least a portion of the shaft into the fixture along the file groove, the portion of the shaft including a first portion of the shaft; contacting the first portion of the shaft with a first displacement member of the one or more displacement members such that the first portion of the shaft is displaced from the file axis thereby forming a first offset portion of the shaft; heating the portion of the shaft while inserted in the fixture to a temperature of at least about 300 C. for a time period of at least about 1 minute to shape-set the portion of the shaft thereby forming a shape-set nonlinear file.

A thick steel plate is provided by heating a continuously-cast slab, hot forging the continuously-cast slab using opposing dies having respective short sides differing such that when a short side length of a die having a shorter one of the short sides is taken to be 1, a short side length of a die having a longer one of the short sides is 1.1 to 3.0, allowing cooling to obtain a steel raw material, reheating the steel raw material, performing hot rolling of the steel raw material including at least two passes carried out, allowing cooling to obtain a thick steel plate, reheating the thick steel plate to at least the Ac.sub.3 temperature and no higher than 1050 C., rapidly cooling the thick steel plate to 350 C. or lower, and tempering the thick steel plate at at least 550 C. and no higher than 700 C.