The present invention reveals an ultra-thin ultra-high strength steel wire, a wire rod for an ultra-thin ultra-high strength steel wire and its producing method. The chemical components of the wire rod comprise in percentage by mass: C 0.90˜0.96%, Si 0.12˜0.30%, Mn 0.30˜0.65%, Cr 0.10˜0.30%, Al≤0.004%, Ti≤0.001%, Cu≤0.01%, Ni≤0.01%, S≤0.01%, P≤0.01%, O≤0.0006%, N≤0.0006%, and the balance is Fe and unavoidable impurity elements. The wire rod for the ultra-thin ultra-high strength steel wire may be used as a base material for producing the ultra-thin ultra-high strength steel wire having a diameter in a range of 50˜60 μm and a tensile strength larger than or equal to 4500 MPa.

In the austenitic stainless steel material of the present disclosure, the chemical composition consists of, by mass %, C: 0.100% or less, Si: 1.00% or less, Mn: 5.00% or less, Cr: 15.00 to 22.00%, Ni: 10.00 to 21.00%, Mo: 1.20 to 4.50%, P: 0.050% or less, S: 0.050% or less, Al: 0.100% or less, N: 0.100% or less, and Cu: 0 to 0.70%, with the balance being Fe and impurities, and an austenite grain size No. determined in accordance with ASTM E112 is from 5.0 to less than 8.0, and in a cross section perpendicular to the longitudinal direction of the austenitic stainless steel material, the dislocation cell structure ratio is from 50 to less than 80%, and the number density of precipitates with a long axis of 1.0 μm or more is 5.0 per 0.2 mm.sup.2 or less.

A wire rod and a steel wire for a high stress suspension spring for motorcycles, wherein decarbonization and low-temperature structure occurrence are easily suppressed when the wire rod and the steel wire are cooled down; and a manufacturing method therefor. A steel wire for a high strength spring includes, in percent by weight (wt %), 0.55 to 0.65% of carbon (C), 0.5 to 0.9% of silicon (Si), 0.3 to 0.8% of manganese (Mn), 0.3 to 0.6% of chromium (Cr), 0.015% or less of phosphorus (P), 0.01% or less of sulfur (S), 0.01% or less of aluminum (Al), 0.005% or less of nitrogen (N), and the remainder of iron (Fe) and inevitable impurities, satisfies Formula (1) below, and comprises 90% or more of a tempered martensite structure. In Formula (1), C, Mn, Cr, and Si denote contents (wt %) of the corresponding elements, respectively. (1) 0.77≤C+(⅙)*Mn+(⅕)*Cr+( 1/24)*Si≤0.83.

A soft magnetic iron comprises a chemical composition containing, in mass %, C: 0.02% or less, Si: 0.05% or less, Mn: 0.010% to 0.500%, P: 0.002% to 0.020%, S: 0.001% to 0.050%, Al: 0.010% to 0.050%, O: 0.0010% to 0.0200%, N: 0.0010% to 0.0100%, and B: 0.0003% to 0.0065%, with a balance consisting of iron and inevitable impurities, wherein a total number density of precipitates of MnS, BN, and a composite compound thereof (MnS+BN) is 5,000/mm.sup.2 or more, and in a frequency distribution of equivalent circular diameters of the precipitates observed in a region of 0.2 mm.sup.2 or more, a mode is 50 nm or more and 250 nm or less and a proportion of precipitates of 600 nm or more in equivalent circular diameter is 7% or more.

Provided are a non-quenched and tempered steel rod wire with improved machinability and toughness and a method for manufacturing the same.

The non-quenched and tempered steel rod according to the present disclosure includes, in percent by weight (wt %), 0.3% to 0.5% of C, 0.4% to 0.9% of Si, 0.5% to 1.2% of Mn, 0.02% or less of P, 0.01% to 0.05% of S, 0.01% to 0.05% of sol.Al, 0.1% to 0.3% of Cr, 0.01% to 0.02% of Ti, 0.0005% to 0.002% of Ca, 0.007% to 0.02% of N, and the remainder being Fe and inevitable impurities, and includes ferrite and pearlite as microstructures and satisfies Relational Expression 1 below:

[00001]$\begin{array}{cc}2\left(\mathrm{Al}+\mathrm{Ti}\right)/N5.& \left[\mathrm{Relational}\mathrm{Expression}1\right]\end{array}$

Disclosed is a mechanical structure steel for cold-working, including: C: 0.32 to 0.44% by mass, Si: 0.15 to 0.35% by mass, Mn: 0.55 to 0.95% by mass, P: 0.030% by mass or less, S: 0.030% by mass or less, Cr: 0.85 to 1.25% by mass, Mo: 0.15 to 0.35% by mass, and Al: 0.01 to 0.1% by mass, with the balance consisting of iron and inevitable impurities, wherein an area ratio of proeutectoid ferrite is 30% or more and 70% or less, and an average grain size of ferrite crystal grains is 5 to 15 μm.

A boron steel high pressure cartridge case and method of manufacturing the same is provided. The method includes cold forming a cartridge case into a drawn blank or a tubular component; annealing the cartridge case using a belt furnace, flame furnace, induction furnace, or a batch furnace; performing a machine ejector slot and trim on the cartridge case; forming the shoulder and neck of the cartridge case; performing a heat treatment of the cartridge case; and tempering the cartridge case. The cartridge case is fabricated of boron steel including ≤1.0% boron.

A steel wire comprising the following elements: 0.30-0.80 wt % carbon, 0.25-0.45 wt % silicon, 0.20-0.70 wt % manganese, 0.008-0.020 wt % titanium, 0.001-0.004 wt % zirconium, wherein at least 50% of the microstructure of the steel wire comprises structures that are sufficiently small to be unresolvable at a magnification of 300×.

The steel material includes a chemical composition containing, in mass %, C: 0.15 to 0.45%, Si: 0.50% or less, Mn: 0.20 to 0.60%, P: 0.015% or less, S: 0.005% or less, Cr: 0.80 to 1.50%, Mo: 0.17 to 0.30%, V: 0.24 to 0.40%, Al: 0.005 to 0.100%, N: 0.0300% or less, O: 0.0015% or less, and the balance being Fe and impurities, and satisfying Formula (1) to Formula (4) described in Embodiment, wherein, in its microstructure, a total area fraction of ferrite and pearlite is 10.0% or more, and a proportion of a content of V (mass %) in electrolytic extraction residue to the content of V (mass %) in the chemical composition is 10.0% or less.

Disclosed is a method for manufacturing high-carbon bearing steel, which include: heating a billet at a temperature of about 950 to 1,050° C. for about 70 to 120 minutes, rolling the billet to manufacture a wire rod, winding the wire rod to manufacture a wire rod coil, cooling the wire rod coil, and subsequently heat treating the wire rod coil for spheroidizing and carbonitriding, respectively. The bearing steel may include an amount of about 0.9 to 1.3 wt % of carbon (C), an amount of about 1.1 to 1.6 wt % of silicon (Si), an amount of about 1.0 to 1.5 wt % of manganese (Mn), an amount of about 1.5 to 1.9 wt % of chromium (Cr), an amount of about 0.2 to 0.6 wt % of nickel (Ni), an amount of about 0.1 to 0.3 wt % of molybdenum (Mo), and the balance iron (Fe) based on the total weight thereof.