A hot rolled wire material which comprises 0.005 to 0.6 mass % of C, and has a structure wherein pseudo-pearlite, bainite and ferrite account for 10 vol % or more, 75 vol % or less and 60 vol % or less, respectively, and the relationship that the sum of (pseudo-pearlite + bainite + ferrite) = 90 vol % is satisfied. A method for producing the above hot rolled wire material which comprises rolling a specific steel, followed by winding up at 750 to 1000 DEG C, cooling the steel from an upper limit temperature of 750 to 1000 DEG C to a lower limit temperature of 400 to 550 DEG C at a cooling rate of 20 DEG C/sec or higher, holding the steel for 20 sec or longer at 400 to 550 DEG C, and then cooling the steel. A steel wire comprises 0.005 to 0.6 mass % of C, and has a structure wherein the distances between cementite particles have a value of (standard deviation/average) of 0.50 or less. A method for producing the steel wire includes subjecting the above hot rolled wire material to spheroidizing annealing.

Hot rolled wire material excellent in cold forging property after spheroidizing treatment, spheroidizing-annealed steel wire having excellent cold forging property, and method for production thereof

PROBLEM TO BE SOLVED: To provide a ferritic stainless steel wire excellent in formability, corrosion resistance, wear resistance and economical efficiency, for use in a muffler hanger of an automobile running in a salt damage district.SOLUTION: The ferritic stainless steel wire excellent in formability and corrosion resistance is provided which contains C:0.02% or less, Si:1.0% or less, Mn:1.0% or less, P:0.04% or less, S:0.03% or less, Cr:10.5% to 25.0%, N:0.025% or less, and further one or more kind of Cu:2.0% or less, Mo:3.0% or less, Ni:5.0% or less and one or more kind of Nb:0.8% or less and Ti:0.5% or less, and which is characterized in that: a crystal grain size number in an inner layer of a cross section vertical to a longer direction is 4.0 to 9.0; a crystal grain size number in a surface layer from a surface to a depth of 1/4×(diameter) is 5.0 to 10.0, namely, the crystal grain size number in the surface layer is larger than that in the inner layer; an average intergranular erosion depth is 0.5 to 1 times the average crystal grain diameter in the surface layer; and hardness of the cross section from the surface to the depth of 1/4×(diameter) is 140 or more.

Ferritic stainless steel wire excellent in formability and corrosion resistance and production method thereof

PROBLEM TO BE SOLVED: To provide a steel material which contains a comparatively large amount of carbon, is used in a machine structural field, and can show excellent cold-forgeability and machinability even when having skipped a spheroidizing step. SOLUTION: The steel for a machine structural use superior in cold-forgeability and machinability satisfies a prescribed component composition; and has a metallurgical structure which is a two-phase structure consisting of ferrite and pearlite, and in which an average space between lamellars of pearlite is 220 to 500 nm, an average particle diameter of pearlite grains is 30 μm or smaller, and a difference between the ferritic grain size numbers in a region from a D/2 point (D: diameter in cross section of steel material) to a D/8 point in the cross section of the steel material and in the outmost surface is 1 or less. COPYRIGHT: (C)2007,JPO&INPIT

Steel superior in cold-forgeability and machinability for machine structural use

PROBLEM TO BE SOLVED: To provide a steel wire rod excellent in a cold-workability, and a producing method thereof. SOLUTION: This steel wire rod is composed, by mass%, of 0.005-0.60% C, 0.01-0.40% Si, 0.20-1.80% Mn, ≤0.040% P, ≤0.050% S and the balance Fe with inevitable impurities and composed of a ferritic structure having ≤15 μm average grain diameter and spheroidal cementite having ≤3 average aspect ratio and ≤0.6 μm average grain diameter, and the pieces of the spheroidal cementite satisfying these conditions, are ≥1.0×10 6 ×C content(%) pieces/mm 2 . COPYRIGHT: (C)2010,JPO&INPIT

Steel wire rod excellent in cold-workability, and producing method thereof

PROBLEM TO BE SOLVED: To provide a BN free-cutting steel capable of drastically extending a tool life SOLUTION: The BN free-cutting steel contains, by mass%, 00050-00150% B, 00070-00200% N, and as Al, satisfies formula (1), 16≥(Al+3N)/B≥6 and desirably, contains 001-12% C, >010-15% Si, 03-20% Mn, >0015 to 02% S, and if necessary, 001-20% Ni, 001-20% Cr, 001-20% Mo, and one or more among Pb, Ca, Se, Te, Bi, Sn, Cu, Zr, Mg, Nb, V and Ti COPYRIGHT: (C)2007,JPO&INPIT

Bn free-cutting steel excellent in tool life

PROBLEM TO BE SOLVED: To provide a linear or bar-shaped steel excellent in cold workability in hot-rolled state as it is even if spheroidizing annealing is eliminate. SOLUTION: This linear or bar-shaped steel is the one in which, in the ferritic structure lying in the range from the center to diameter/8 of a rolling stock, carbides are present by >=25 pieces/25 μm2 on the average, where the one in which carbides are composed of ferrous carbides such as cementite is a preferable one, and by precipitating such carbides, its deformation resistance in the temp. rising region (about 100 to 350 deg.C) generated by working heat generation can be reduced.

Linear or bar-shaped steel and machine parts

PROBLEM TO BE SOLVED: To produce a medium-high carbon steel excellent in cold forgeability even as non-refined and capable of securing strength not by the addition of special alloy components but by the structural control of the steel. SOLUTION: This medium-high carbon steel excellent in cold forgeability is the one contg., by mass, 0.40 to 1.0% C, in which the value of Ceq (=C+Si/24+Mn/6+(Cr+Mo)/5+Ni/40+(Ti+Nb+V)/5+5×B) is also controlled to 0.6 to 1.2%, furthermore, the main structure is formed of pearlite and/or pseudo- pearlite, the volume ratio of the 2nd 6 phases composed of one or more kinds among ferrite, bainite, martensite, and pro-eutectoid cementite is controlled to <=7%, the size of pro-eutectoid ferrite precipitated into old austenite grains is, controlled to <=4 μm, the nodule size of the pearlite is controlled to 4.0 to 20 μm, and the lamellar interval of the pearlite is controlled to <=120 nm.

Medium-high carbon steel excellent in cold forgeability

PROBLEM TO BE SOLVED: To establish a technology for improving a machinability after being cold worked, particularly a swarf treatment property, which particularly aims at a steel to be machined after being cold worked. SOLUTION: A steel for cold forging superior in the swarf treatment property after being cold worked comprises 0.001-0.01% B (% means mass% hereafter), 0.002-0.01% N and 0.005-0.10% Bi, and has 15 or more precipitates of BN and B-containing Bi with diameters of 0.7 μm or larger, per visual field of 0.5 mm×0.5 mm in a cross section of the steel. COPYRIGHT: (C)2004,JPO

Steel for cold forging superior in swarf treatment property

PROBLEM TO BE SOLVED: To allow steel to have specified carbon and nitrogen peak heights in an internal friction test and to impart excellent cold workability thereto by allowing it to have a specified compsn. contg. C, Sol.Al and N, and the balance Fe with inevitable impurities. SOLUTION: By preparing steel having chemical components of, by mass, 0.002 to 0.85% C, <=0.1% (not including zero) Sol.Al and 0.015% (not including zero) N, satisfying 2.0 <=Sol.Al/N<15, and the balance Fe with inevitable impurities, steel in which the peak height of carbon in an internal friction test is controlled to <=2.0×10-4, and the peak height of nitrogen is controlled to <=1.7×10-4 is obtd. Moreover, this steel may positively be added with at least one kind selected from the group consisting of <=2% Cr, <=0.2% Ti, <=0.01% B, <=0.1% Nb, <=0.2% V, <=0.1% Zr and <=0.3% Mo (0% is not included in all elements).

Steel excellent in cold workability and machine parts

PROBLEM TO BE SOLVED: To provide a wire-shaped or bar-shaped steel which is excellent in deformablity and has high strength as a steel material itself only by hot rolling even when spheroidizing annealing is omitted. SOLUTION: The wire-shaped or bar-shaped steel substantially has a ferrite structure, and ferrite grain size number (A) in the ferrite structure within a range between a center and a diameter/4 of a rolled material is 7.0 to 10.0, ferrite grain size number (B) in the ferrite structure at an uppermost layer of the rolled material is 7.0 to 10.0. Further (A) and (B) satisfy a relation: 0<=(B)-(A)<=0.5.

Momozaki Hiroshi

Papers

Linear or bar-shaped steel and machine parts

Medium-high carbon steel excellent in cold forgeability

Steel for cold forging superior in swarf treatment property

Steel excellent in cold workability and machine parts

Wire-shaped or bar-shaped steel excellent in deformability and machine part