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.

The present invention provides a novel heat exchange medium to replace lead. A carbon-steel wire 1A heated in a heating furnace 11 is passed through a bath 12A filled with a liquid-phase Mg—Al—Ca alloy 20 obtained by melting a Mg—Al—Ca alloy in which the main constituent elements are Mg (magnesium), Al (aluminum) and Ca (calcium). When it passes through the bath 12A, the carbon-steel wire 1A, which has been heated for example to about 950° C. in the heating furnace 11, is cooled to about 550° C. The Mg—Al—Ca alloy is non-toxic and has no environmental impact as well.

The present invention provides a novel heat exchange medium to replace lead. A carbon-steel wire 1A heated in a heating furnace 11 is passed through a bath 12A filled with a liquid-phase Mg—Al—Ca alloy 20 obtained by melting a Mg—Al—Ca alloy in which the main constituent elements are Mg (magnesium), Al (aluminum) and Ca (calcium). When it passes through the bath 12A, the carbon-steel wire 1A, which has been heated for example to about 950° C. in the heating furnace 11, is cooled to about 550° C. The Mg—Al—Ca alloy is non-toxic and has no environmental impact as well.

Provided is a plated steel wire including: a steel wire; and a brass plating layer covering the surface of the steel wire and composed of Cu, Zn, Al, and impurities in which, assuming the total of Cu, Zn, and Al to be 100% by mass, the Cu content is from 60% by mass to less than 70% by mass and the Al content is from 5.5% by mass to less than 15% by mass, and the average thickness is from 180 nm to 2,000 nm.

Provided is a wiredrawn product drawn from a heat-treated steel containing: 0.38 to 1.05% by mass of C; 0.0 to 1.0% by mass of Mn; 0.0 to 0.50% by mass of Cr; and 0.0 to 1.5% by mass of Si, with the remainder being Fe and unavoidable impurities, wherein a GOS value/average crystal grain size is greater than or equal to ?0.6?GAM value+1.5 at a grain boundary setting angle of 2? and a step number of 0.07 ?m.

A filament according to an aspect of the present invention includes a predetermined chemical composition, in which a diameter r of the filament is 0.15 mm to 0.35 mm, a soft portion is formed along an outer circumference of the filament, the Vickers hardness of the soft portion is lower than that of a position of the filament at a depth of of the diameter r by Hv 50 or higher, the thickness of the soft portion is 1 m to 0.1r mm, the metallographic structure of a center portion of the filament contains 95% to 100% of pearlite by area %, the average lamellar spacing of pearlite in a portion from a surface of the filament to a depth of 1 m is less than that of pearlite at the center of the filament, the difference between the average lamellar spacing of pearlite in the portion from the surface of the filament to the depth of 1 m and the average lamellar spacing of pearlite at the center of the filament is 2.0 nm or less, and the tensile strength is 3200 MPa or higher.

A filament according to an aspect of the present invention includes a predetermined chemical composition, in which a diameter r of the filament is 0.15 mm to 0.35 mm, a soft portion is formed along an outer circumference of the filament, the Vickers hardness of the soft portion is lower than that of a position of the filament at a depth of of the diameter r by Hv 50 or higher, the thickness of the soft portion is 1 m to 0.1r mm, the metallographic structure of a center portion of the filament contains 95% to 100% of pearlite by area %, the average lamellar spacing of pearlite in a portion from a surface of the filament to a depth of 1 m is less than that of pearlite at the center of the filament, the difference between the average lamellar spacing of pearlite in the portion from the surface of the filament to the depth of 1 m and the average lamellar spacing of pearlite at the center of the filament is 2.0 nm or less, and the tensile strength is 3200 MPa or higher.

To provide a heat-treated steel excellent in both tensile strength and toughness.

A heat-treated steel contains 0.38 to 1.05% by mass of C, 0.0 to 1.0% by mass of Mn, 0.0 to 0.50% by mass of Cr, and 0.0 to 1.5% by mass of Si with the remainder being Fe and unavoidable impurities, wherein an average crystal grain size at a grain boundary setting angle of 15 is 10C+7 (m) or less (wherein, C represents a carbon content (%)).

To provide a high-carbon steel wire rod with excellent wire drawability. The high-carbon steel wire rod of the present invention includes predetermined components and also includes pearlite and proeutectoid cementite, and an area ratio of pearlite is 90% or more relative to the entire structure, a maximum length of proeutectoid cementite is 15 m or less, and a concentration difference between an average of the Si concentration inside proeutectoid cementite and a maximum value of the Si concentration inside ferrite that forms a lamellar structure of pearlite is 0.50 to 3%.

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 m or less.