An NPR non-magnetic steel material for rock bolt and a production method thereof are disclosed. The NPR non-magnetic steel material for rock bolt has a composition, in weight percent, consisting of: C: 0.4-0.7%, MN: 15-20%, Cr: 1-18%, Si: 0.3-3%, Ca: 0.05-0.15%, Cu: ≤0.03%, Ni: ≤0.02%, S: ≤0.001%, P: ≤0.001%, and the rest being Fe and unavoidable impurity elements. The NPR non-magnetic steel material for rock bolt and the production method thereof effectively solve the problems of steel materials for rock bolt in the prior art such as strong magnetism, low tensile strength and low effective elongation. The NPR non-magnetic steel material for rock bolt has a fully-austenitized structure and is non-magnetic, its yield strength is adjustable in the range of 600-1000 MPa, and its elongation is adjustable in the range of 20-60%.

A copper alloy trolley wire is formed of a composition containing Mg in a range of 0.15% by mass or more and 0.50% by mass or less, Cr in a range of 0.25% by mass or more and 1.0% by mass or less, and a Cu balance containing inevitable impurities, in which a tensile strength is 600 MPa or higher and an electrical conductivity is 60% IACS or higher.

A cold rolled steel wire having the following chemical composition expressed in percent by weight, 0.2≤C %≤0.6, 0.5≤Mn %≤1.0, 0.1≤Si≤0.5%, 0.2≤Cr≤1.0%, P≤0.020%, S≤0.015%, N≤0.010%, and optionally not more than 0.07% Al, not more than 0.2% Ni, not more than 0.1% Mo and not more than 0.1% Cu, the balance being iron and the unavoidable impurities due to processing. This wire has a microstructure including bainite and, optionally, up to 35% acicular ferrite and up to 15% pearlite. A fabrication method and flexible conduits for hydrocarbon extraction are also provided.

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 copper alloy wire is composed of a copper alloy including indium. of 0.3 mass % or more and 0.65 mass % or less, and has 0.2% proof stress of 300 MPa or more, electrical conductivity of 80% IACS or more, and elongation of 7% or more.

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

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×.

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.

A forged component having a chemical composition including, by mass %, C: 0.30 to 0.45%, Si: 0.05 to 0.35%, Mn: 0.50 to 0.90%, P: 0.030% or less, S: 0.040 to 0.070%, Cr: 0.01 to 0.50%, Al: 0.001 to 0.050%, V: 0.25 to 0.35%, Ca: 0 to 0.0100%, N: 0.0150% or less, and the balance being Fe and unavoidable impurities, and satisfying Formulae 1 through 3. The: metal structure is a ferrite pearlite structure, and a ferrite area ratio is 30% or more; Vickers hardness is in the range of 320 to 380 HV; 0.2% yield strength is 800 MPa or more; a Charpy V-notch impact value is in the range of 15 to 25 J/cm.sup.2: and an unevenness of fracture surface (surface area/cross sectional area) of the Charpy test piece after fracture is in the range of 1.47 to 1.60.