A spring steel having a superior fatigue life, and a manufacturing method for the same. The chemical components thereof are as follows in weight percentage: C: 0.52-0.62%, Si: 1.20-1.45%, Mn: 0.25-0.75%, Cr: 0.30-0.80%, V: 0.01-0.15%, Nb: 0.001-0.05%, N: 0.001-0.009%, O: 0.0005-0.0040%, P: ≤0.015%, S: ≤0.015%, and Al: ≤0.0045%, with the remainder being Fe and incidental impurities, wherein the following condition is also met 0.02≤(2Nb+V)/(20N+C)≤0.40. The spring steel of the present invention has a microstructure of tempered troostite+tempered sorbite, a prior austenite grain size less than 80 um, a size of alloy nitride and carbide precipitates being 5-60 nm, and a maximum width of single-grain inclusions being less than 30 pm. The spring steel has a handling strength greater than 2020 MPa, superior ductility and toughness (the reduction of area≥40%), and a fatigue life≥800,000 times, thereby meeting application requirements of high-stress springs in industries, such as automobiles, machinery, and the like.

The invention provides a production method for stabilizers which produces with high productivity in a compact production line, without tempering. The production method for stabilizers of the invention includes: forming a steel bar material containing at least C: 0.15 wt % to 0.39 wt %, Mn, B and Fe into a product shape by bending; and quenching the bent steel bar material in a medium having a heat transfer coefficient higher than or close to that of water.

Disclosed are a wire rod and a manufacturing method therefor. The wire rod comprises in percentage by weight: 0.02 to 0.15% of C; 0.05 to 0.3% of Si; 0.5 to 1.2% of Mn; 0.3 to 0.9% of Cr; 0.02% or less of P; 0.02% or less of S; 0.01 to 0.05% of sol. Al; 0.01% or less of N; Fe as the remainder; and unavoidable impurities, wherein the wire rod satisfies following formulas 1 and 2, wherein, when the hardness of the wire rod measured in 1/2d position and in 1/4d position in the diameter direction of the wire rod is Hv,.sub.1/2d(Hv) and Hv,.sub.1/4d(Hv), respectively (here, d is the diameter of the wire).
(Hv,.sub.1/2d+Hv,.sub.1/4d)/2≤150  [Formula 1]
Hv,.sub.1/2d/Hv,.sub.1/4d≤1.2  [Formula 2]

An embodiment of the present invention provides a wire rod and a steel wire which are for springs and have excellent corrosion fatigue resistance properties, and a method for producing same, the wire rod and steel wire containing, in wt %, 0.40-0.70% of C, 1.20-2.30% of Si, 0.20-0.80% of Mn, 0.20-0.80% of Cr, 0.015% or less of P, 0.015% or less of S, and 0.010% or less of N, with the remainder comprising Fe and other unavoidable impurities, along with at least one among 0.01-0.20% of V and 0.01-0.10% of Nb, wherein the V and Nb satisfy relational expression 1 below, the average grain size of prior austenite is no greater than 20 m, and the surface decarburization depth is no greater than 0.1 mm. [Relational expression 1] [V]+[Nb]0.08 (where the V and Nb contents are in wt %)

There is provided a steel cord including a steel wire and a plating layer that covers the steel wire and has Cu, Zn, and Co, wherein Cu and Zn are alloyed and a region covered with Co and a region not covered with Co are mixed on the outermost surface of the plating layer.

A Fe-based shape memory alloy material, containing 25 atom % to 42 atom % of Mn, 9 atom % to 13 atom % of Al, 5 atom % to 12 atom % of Ni, and 5.1 atom % to 15 atom % of Cr, with the balance being Fe and unavoidable impurities; a method of producing the same; and a wire material and sheet material composed of the alloy material.

The present disclosure provides a wire rod for cold heading that can shorten the spheroidizing heat treatment time, processed products using the same, and manufacturing method thereof. A wire rod for cold heading according to an embodiment of present disclosure includes, in percent (%) by weight of the entire composition, C: 0.15 to 0.5%, Si: 0.1 to 0.4%, Mn: 0.3 to 1.5%, Cr: 0.1 to 1.5%, Al: 0.02 to 0.05%, N: 0.004 to 0.02%, at least one selected from the group consisting of Nb: 0.001 to 0.03%, V: 0.01 to 0.3%, Mo: 0.01 to 0.5%, Ti: 0.001 to 0.03%, and the remainder of iron (Fe) and other inevitable impurities, and the microstructure has a long and short axis ratio of cementite present in pearlite colonies of 200:1 or less.

An NPR steel material for rock bolt and a production method thereof are disclosed. The NPR steel material for rock bolt has a composition, in weight percent, consisting of: C: 0.4-0.7%, Mn: 15-20%, Si: 0.1%, Cu: 0.03%, Cr: 0.01%, Ni: 0.02%, S: 0.001%, P: 0.001%, and the rest being Fe and unavoidable impurity elements. The NPR steel material for rock bolt and the production method thereof effectively solve the problem that rock bolts in the prior art have low tensile strength and low effective elongation. The NPR steel material for rock bolt has a yield strength adjustable in the range of 500-1100 MPa, and an elongation adjustable in the range of 10-80%.

Austenitic stainless steel with improved heat resistant and corrosion resistance, where the steel contains in weight % Carbon 0.03-0.20 Chromium 20.00-26.00 Nickel 10.00-22.00 Silicon 0.50-2.50 Maganese 0.50-2.00 Nitrogen 0.10-0.40 Sulphur <0.015 Phosphous <0.040 Rare earth metals, mainly cerium and lanthanum 0.00-0.10 and the rest being iron (Fe) and inevitable impurities.

Chemical compositions of a tire cord steel with high strength and low wire breakage rate may include Nb, V and N, and ([Nb]+[V])/[N] is 3-4.5, [Nb] representing the mass fraction of niobium element, [V] representing the mass fraction of vanadium element, and [N] representing the mass fraction of nitrogen element. The method includes: obtaining a steel billet of the tire cord steel; and sequentially performing a heating-before-rolling, a hot-rolling and a cooling-after-rolling on the steel billet to obtain a wire rod of the tire cord steel. The application of the tire cord steel is to apply the tire cord steel in tire skeleton materials. The strength and toughness of the tire cord steel can be improved by adding Nb, V and N, and then controlling the relationship between Nb, V and N.