Provided are a non-quenched and tempered wire rod having excellent drawability and impact toughness suitable for materials for automobiles or mechanical parts and a method of manufacturing the same. According to an embodiment of the present disclosure, the non-quenched and tempered wire rod includes, in percent by weight (wt %), 0.05 to 0.35% of carbon (C), 0.05 to 0.5% of silicon (Si), 0.5 to 2.0% of manganese (Mn), 1.0% or less of chromium (Cr), 0.03% or less of phosphorus (P), 0.03% or less of sulfur (S), 0.01 to 0.07% of soluble aluminum (sol.Al), 0.01% or less of nitrogen (N), at least one of 0.1% or less of niobium (Nb), 0.5% or less of vanadium (V), and 0.1% or less of titanium (Ti), and the remainder of iron (Fe) and inevitable impurities, and includes a ferrite-pearlite layered structure, as a microstructure, in a rolling direction.

A method to manufacture a steel wire spring core for a mattress or for seating is described, which comprises the steps of providing a carrier comprising steel wire; repeatedly cold coiling a steel wire spring from steel wire taken from the carrier; and connecting a series of the coiled steel wire springs to each other. The steel wire has a diameter d between 0.8 and 4.5 mm; and has a drawn pearlitic microstructure. The steel wire comprises a steel alloy having a carbon content between 0.35 wt % and 0.85 wt %. The steel wire on the carrier has a ratio—expressed as a percentage—of the yield strength R.sub.po 2 (in MPa) over the tensile strength R.sub.m (in MPa) higher than 85%.

The present disclosure relates to a steel wire rod enabling the omission of softening heat treatment and a method of manufacturing same. An embodiment of the present disclosure provides a steel wire rod enabling the omission of softening heat treatment and a method of manufacturing same, the steel wire rod comprising, in weight %, 0.2-0.45% of C, 0.02-0.4% of Si, 0.3-1.5% of Mn, 0.01-1.5% of Cr, 0.02-0.05% of Al, 0.01-0.5% of Mo, 0.01% or less of N, and the balance Fe and other unavoidable impurities, wherein the microstructure of the steel wire rod is a composite structure of proeutectoid ferrite+perlite as a main phase; the steel wire rod contains 10 area % or less (including 0%) of at least one of bainite or martensite; and the average colony size of the perlite is 5 μm or less.

This hot-rolled wire rod includes, as a chemical composition, by mass %: C: 0.90% to 1.10%; Si: 0.50% to 0.80%; Mn: 0.10% to 0.70%; Cr: 0.10% to 0.40%; P: 0.020% or less; S: 0.015% or less; N: 0.0060% or less; O: 0.0040% or less; and a remainder consisting of Fe and impurities, in which Formulas (1) and (2) are satisfied by mass %, the structure of the hot-rolled wire rod consists of pearlite in an area ratio of 95.0% or more and a remainder, and TS, which is a tensile strength in unit of MPa, and TS*, which is determined from the C content, the Si content, and the Cr content, satisfy Formula (3),

0.50≤[Si]+[Cr]≤0.90  (1)

0.40≤[Cr]+[Mn]≤0.80  (2)

−50<TS−TS*<50  (3) where the TS* is calculated by Formula (3′),

TS*=1000×[C]+100×[Si]+125×[Cr]+150  (3′).

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 method for producing a feedstock wire is produced from a first metal strip and at least one further metal strip by roll forming, wherein in particular the first metal strip and the at least one further metal strip are made of differing metals, preferably of differing meals having differing yield points, wherein a jacket, which in the final shape completely surrounds the at least one further metal strip in the circumferential direction, is formed from the first metal strip in a plurality of passes by roll forming using a plurality of roll stands, and wherein, first, exclusively only the first metal strip is formed to a preliminary shape in a plurality of passes using a first group of roll stands and, thereafter, the first metal strip and the at least one further metal strip are jointly formed to the final shape in a second group of roll stands.

Provided is a steel comprising the following chemical composition in percentage by mass: 0.150-0.250% of C, 0.10-0.50% of Si, 0.60-1.50% of Mn, 0.30-1.20% of Cr, 0.20-0.80% of Mo, 2.00-4.00% of Ni, 0-0.10% of Nb, 0.0010-0.0050% of B, 0-0.12% of V, 0.003-0.06% of Ti, 0.01-0.08% of Al, the balance being Fe and unavoidable impurities. Also provided is a steel bar and a manufacturing method thereof. The steel bar is made from the above steel. The manufacturing method comprises the steps of smelting and casting, heating, forging or rolling, quenching, and tempering.

Disclosed is an iron-manganese alloy including, by weight: 25.0%≤Mn≤32.0%; 7.0%≤Cr≤14.0%; 0≤Ni≤2.5%; 0.05%≤N≤0.30%; 0.1≤Si≤0.5%; and optionally 0.010%≤rare earths≤0.14%. The remainder being iron and residual elements resulting from manufacturing.

Carbon steel for a rack bar contains 0.50 to 0.55% by weight of carbon (C), 0.15 to 0.35% by weight of silicon (Si), 0.75 to 0.95% by weight of manganese (Mn), 0.025% by weight or less of phosphorus (P), 0.025% by weight or less of sulfur (S), 0.65 to 0.85% by weight of chrome (Cr), 0.20% by weight or less of molybdenum (Mo), 0.001 to 0.02% by weight of aluminum (Al), 5 to 50 ppm of boron (B), and iron (Fe) as a remainder and unavoidable impurities. A method for manufacturing the rack bar includes quenching, tempering, and drawing the carbon steel and warm forging the drawn carbon steel.

A bar-shaped steel product extends unidirectionally and has a chemical composition including, by mass %, 0.001 to 0.20% of C, 0.01 to 3.0% of Si, 0.01 to 2.0% of Mn, 0.01 to 5.0% of Ni, 7.0 to 35.0% of Cr, 0.01 to 5.0% of Mo, 0.01 to 3.0% of Cu, 0.001 to 0.10% of N, 0.2 to 2.0% of Nb, optional element(s), and a balance consisting of Fe and inevitable impurities, and has 0.5 or less of a rolling-direction-crystal-orientation RD//<100> fraction (an area ratio of crystal having 20 degrees or less of an orientation difference between a <100> orientation and a rolling direction).