A steel wire which has an excellent fatigue limit when made into a spring is provided. A chemical composition of the steel wire according to the present embodiment consists of, in mass %, C: 0.53 to 0.59%, Si: 2.51 to 2.90%, Mn: 0.70 to 0.85%, P: 0.020% or less, S: 0.020% or less, Cr 1.40 to 1.70%, Mo: 0.17 to 0.53%, V: 0.23 to 0.33%, Cu: 0.050% or less, Ni: 0.050% or less, Al: 0.0050% or less, Ti: 0.050% or less, N: 0.0070% or less, Ca: 0 to 0.0050%, and Nb: 0 to 0.020%, with the balance being Fe and impurities. In the steel wire, a number density of V-based precipitates having a maximum diameter ranging from 2 to 10 nm is 500 to 8000 pieces/μm.sup.2.

Provided is a solid wire for gas metal arc welding, which has a small amount of fume during welding and is suitable as a welding material for high Mn steel materials. The wire has a chemical composition containing, in mass %, C: 0.2% to 0.8%, Si: 0.15% to 0.90%, Mn: 17.0% to 28.0%, P: 0.03% or less, S: 0.03% or less, Ni: 0.01% to 10.00%, Cr: 0.4% to 4.0%, Mo: 0.01% to 3.50%, B: less than 0.0010%, and N: 0.12% or less, with the balance consisting of Fe and inevitable impurities. It may contain at least one selected from V, Ti, Nb, Cu, Al, Ca and REM, if necessary. The wire has excellent manufacturability, can significantly suppress the amount of fume generated during gas metal arc welding, and can easily manufacture a weld joint having high strength and excellent impact toughness at cryogenic temperatures.

The present disclosure relates to a CHQ wire rod that has improved resistance to hydrogen delayed fracture while securing cold forging characteristics by reducing Si content and adding Mo and V, a processed product using the same, and a manufacturing method thereof. In accordance with an aspect of the present disclosure, a CHQ wire rod includes, in percent (%) by weight of the entire composition, C: 0.3 to 0.5%, Si: 0.1 to 0.3%, Mn: 0.5 to 1.0%, at least two or more of Cr: 0.5 to 1.5%, Mo: 0.5 to 1.5%, V: 0.01 to 0.2%, the remainder of iron (Fe) and other inevitable impurities, and the value of the following formula (1) is 3.56 or more.

Disclosed are a steel wire rod having excellent low temperature impact toughness and a manufacturing method therefor. The steel wire rod having excellent low temperature impact toughness according to an embodiment of the present invention contains, by weight %, carbon (C): 0.40-0.90%, silicon (Si): 0.5-1.0%, manganese (Mn): 11-25%, copper (Cu): 1.0-3.0%, phosphorus (P): 0.020% or less, sulfur (S): 0.020% or less, aluminum (Al): 0.010-0.050%, nitrogen (N): 0.0010-0.0050%, and the remainder being Fe and unavoidable impurities. The steel wire rod has a microstructure which contains an austenite phase having an area fraction of 95% or more, and a volume fraction of a deformation twin formed in an austenite grain is 1-8%. Therefore, it is possible to provide a steel wire rod having excellent low temperature impact toughness used in industrial machines or automobile parts, etc.

A stabilizer formed by using a metal bar having a solid structure and configured to reduce a displacement between right and left wheels, including a torsion part extending in a vehicle width direction, being capable of a torsional deformation, and having a diameter of 10 to 32 mm, is provided. The stabilizer has a chemical composition containing at least C: 0.15% by mass or more to 0.39% by mass or less, Mn, B, and Fe, and also has a metal structure 90% or more of which is a martensite structure.

There is provided a hot rolled steel according to one aspect of the invention including, as a predetermined chemical composition: Bi: 0.0001 mass % to 0.0050 mass %, in which 90 area % or more of a metallographic structure is configured with a ferrite and a pearlite, and an average number density of Mn sulfides measured on a cross section parallel to a rolling direction having an aspect ratio of more than 10 and 30 or less which is extended along the rolling direction, is 50 pieces/mm.sup.2 to 200 pieces/mm.sup.2.

Disclosed are a wire rod and a manufacturing method therefor, the wire rod comprising, by weight %: 0.05-0.20% of C, 0.2% or less of Si, 5.0-6.0% of Mn, 0.020% or less of P, 0.020% or less of S, 0.010-0.050% of Al, 0.010-0.020% of N, and a balance of Fe and inevitable impurities and having a microcrystalline structure composed of two phases of austenite and ferrite, wherein the austenite has an area fraction of 15-25%.

A high-strength and corrosion-resistant sucker rod and a preparation process thereof are disclosed. Raw materials for preparing the high-strength and corrosion-resistant sucker rod include, by weight percent, Mn: 0.70% to 1.20%, Cr: 9.50% to 13.50%, Ni: 0.65% to 1.10%, Mo: 0.10% to 0.90%, Cu: 0.28% to 0.56%, C: ≤0.07%, Si: ≤0.50%, P: ≤0.08%, and S: ≤0.005%, the balance is Fe and unavoidable impurities. The sucker rod prepared by the new process has an actual grain size equal to or greater than grade 8, excellent mechanical properties that meet the standard of grade HL specified in SY/T5029 Sucker Rods, and excellent corrosion fatigue resistance. The preparation process is simple and easy for operation, and suitable for large-scale promotion.

A non-heat treated steel bar according to the present disclosure has a chemical composition consisting of, in mass percent, C: 0.39 to 0.55%, Si: 0.10 to 1.00%, Mn: 0.50 to 1.50%, P: 0.010 to 0.100%, S: 0.040 to 0.130%, Cr: 0.05 to 0.50%, V: 0.05 to 0.40%, Ti: 0.10% to 0.25%, Al: 0.003 to 0.100%, and N: 0.020% or less, with the balance being Fe and impurities, and satisfying Formula (1). A number density of Al.sub.2O.sub.3-based inclusions in each of which Al.sub.2O.sub.3 is contained at 70.0% or more in mass % and √AREA is not less than 3 μm is 0.05 to 1.00/mm.sup.2.
0.60≤C+0.2Mn+0.25Cr+0.75V+0.81Mo≤1.00  (1)

A rolled wire rod for spring steel contains, as a chemical composition, by mass %: C: 0.42% to 0.60%; Si: 0.90% to 3.00%; Mn: 0.10% to 1.50%; Cr: 0.10% to 1.50%; B: 0.0010% to 0.0060%; N: 0.0010% to 0.0070%; Mo: 0% to 1.00%; V: 0% to 1.00%; Ni: 0% to 1.00%; Cu: 0% to 0.50%; Al: 0% to 0.100%; Ti: 0% to 0.100%; Nb: 0% to 0.100%; P: limited to less than 0.020%; S: limited to less than 0.020%; and a remainder including Fe and impurities, the carbon equivalent (Ceq) is 0.75% to 1.00%, the area fraction of tempered martensite and bainite included in a microstructure is 90% or greater, the tensile strength is 1,350 MPa or less, and the reduction of area is 40% or greater.