An oil ring wire (2) containing an alloy steel as a material. The alloy steel contains: 0.50 to 0.65% by mass C; 1.60 to 2.30% by mass Si; 0.60 to 1.10% by mass Mn; 0.75 to 1.15% by mass Cr; 0.18 to 0.45% by mass Ni; 0.05 to 0.15% by mass V; and 0.15% by mass or less Cu. In the oil ring wire 2, an area percentage of a carbide is 1.00% or less. Also disclosed is a method of producing the oil ring wire.

A continuous annealer for wire is disclosed, and specifically for annealing and recrystallizing a wire in a continuous process. The continuous annealer for wire comprises: two contact discs for contacting a first wire portion extending therebetween; an annealing zone situated between the two contact discs; and annealing means for annealing the first wire portion in the annealing zone, as a result of which a first partial recrystallisation process in the first wire portion takes place in the annealing zone. A recrystallisation zone is situated downstream of the second contact disc, wherein, downstream of the annealing zone, the first wire portion passes through the recrystallisation zone as the second wire portion, and a second partial recrystallisation process takes place in the second wire portion. The wire has the opportunity to recrystallize further after leaving the annealing zone without further heating. By extending the recrystallisation time, the recrystallisation temperature can be reduced accordingly. As a result, the same degree of recrystallisation can be achieved overall with a significantly lower input of energy than when the wire is cooled immediately after leaving the annealing zone.

The present invention discloses a 400 MPa corrosion-resistant steel bar and a production method thereof. The steel bar includes the following chemical ingredients: 9.5-10.4% of Cr, 1.0-1.2% of Mo, 0.3-0.6% of Mn, 0.01-1% of Ni, 0.01-0.5% of Cu, at most 0.014% of C, at most 0.004% of N, 0.01-0.05% of Nb, 0.2-0.6% of Si, and the balance of Fe, where Cr+Mo+0.5Mn+0.35Ni+0.25Cu is 11.1-12.2%, and C+N+0.3Si+Mn+1.8Nb is 0.4-0.8%.

Disclosed are wire rods and parts with improved delayed fracture resistance, and methods for manufacturing the same. The wire rod with improved delayed fracture resistance according to the present disclosure contains, by wt %, 0.15-0.30% of C, 0.15-0.25% of Si, 0.95-1.35% of Mn, 0.030% or less of P, 0.030% or less of S, 0.015-0.030% of Ti, 0.0010-0.0040% of B, 0.0010-0.0080% of N, and Fe and inevitable impurities as the balance, and satisfies formula 1 of 2.05.5[Si]+[Mn]2.4, where [Si] and [Mn] represent the contents (wt %) of the corresponding elements.

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 in the present specification are: a high-strength wire rod for cold heading, having superior heat treatment characteristics and resistance of hydrogen-delayed fracture characteristics, the rod being applicable to a bolt, etc.; a heat-treated component; and a method for manufacturing the same. According to an exemplary embodiment, the high-strength wire rod for cold heading with superior heat treatment characteristics and resistance of hydrogen-delayed fracture characteristics comprises, by wt %, 0.3-0.6% of C, 0.05-0.3% of Si, 0.2-1.0% of Mn, 0.5-2.0% of Cr, 0.5-2.0% of Mo, 0.02-0.05% of Al, 0.01-0.03% of N, and Fe and other impurities as the balance, and has a microstructure comprising, by area fraction, 80% or more of bainite, 1-15% of pearlite and 0.1-2% of martensite, and comprises 210.sup.19/m.sup.3 or more of aluminum nitride having a diameter of 5-50 nm.

Disclosed in the present specification are: a wire rod for ultrahigh-strength springs, which can be applied to motorcycle suspension springs; a steel wire; and a manufacturing method therefor. According to one embodiment of the disclosed wire rod for ultrahigh-strength springs, the wire rod comprises, by wt %, 0.5-0.7% of C, 0.4-0.9% of Si, 0.3-0.8% of Mn, 0.2-0.6% of Cr, 0.015% or less of P, 0.010% or less of S, 0.01% or less of Al, 0.01% or less of N, 0.005% or less of O, and the balance of Fe and inevitable impurities, wherein in 1 mm2 area of the center of the cross-section perpendicular to the longitudinal direction, the proportion of the area satisfying at least one from among C>0.8%, Si>0.9%, Cr>0.8% and Mn>0.8% by wt % can be 5% or less.

Disclosed are a wire rod and a steel wire for a spring, a spring with improved fatigue resistance and nitriding property, and methods for manufacturing same. The wire rod for a spring with improved fatigue resistance and nitriding property according to the present disclosure contains, by wt %, 0.6-0.7% of C, 2.0-2.5% of Si, 0.2-0.5% of Mn, 0.9-1.6% of Cr, 0.015% of less of P, 0.01% of less of S, 0.01% of less of Al, 0.007% of less of N, 0.1-0.25% of Mo, 0.1-0.25% of V, and Fe and inevitable impurities as the balance, wherein Cr+Mn is 1.8% or less, Mo/V is 1.5 or less, and the microstructure includes 60% or more of a pearlite structure in the C section.

Disclosed are high-strength wire rods and parts, having improved delayed fracture resistance, for use in bolts, and a methods for manufacturing the same. The high-strength wire rod, having improved delayed fracture resistance, for use in bolts according to the present disclosure contains, by wt %, 0.15-0.30% of C, 0.05-0.35% of Si, 0.95-1.35% of Mn, 0.030% or less of P, 0.030% or less of S, 0.005-0.030% of Ti, 0.0010-0.0040% of B, and Fe and inevitable impurities as the balance.

Disclosed is a non-quenched and tempered round steel with high strength, high toughness and easy cutting, comprising the following chemical elements in percentage by mass: C: 0.36-0.45%, Si: 0.20-0.70%, Mn: 1.25-1.85%, Cr: 0.15-0.55%, Ni: 0.10-0.25%, Mo: 0.10-0.25%, Al: 0.02-0.05%, Nb: 0.001-0.040%, V: 0.10-0.25%, S: 0.02-0.06%, and the balance being Fe and inevitable impurities. Also disclosed is a method for manufacturing the non-quenched and tempered round steel, comprising the steps of: S1: smelting and casting; S2: heating; S3: forging or rolling; and S4: finishing. The non-quenched and tempered round steel with high strength, high toughness and easy cutting described above has high strength, good impact toughness, elongation and cross-sectional shrinkage, and has good cutting performance and fatigue resistance, and can be used in situations requiring a high-strength steel material, such as automobiles and engineering machinery.