Jfe Steel Corporation

Tokushu Kinzoku Excel Co., Ltd.

Yuka Miyamoto

Norihiko Nakamura

Yoichi Tobiyama

Takeshi Suzuki

Takashi Kobayashi

Takeshi Yokota

Yasuhiro Sakurai

Hiroki Iwasa

Chikara Kami

Kaneharu Okuda

Hisato Noro

Masao Inose

Yoichiro Matsui

Yoshimasa Funakawa

Hiroki Ota

Yoshihiko Ono

Nobuyuki Nakamura

Yasunobu Nagataki

Kazuhiro Seto

Hideyuki Kimura

Yoshihiro Hosoya

Shunsuke Toyoda

Hayato Saito

Shogo Sato

Eiji Tsuchiya

Yuta Matsumura

A high-carbon hot-rolled steel sheet and a method for manufacturing the steel sheet are provided. The high-carbon hot-rolled steel sheet has a particular chemical composition. The microstructure of the steel sheet includes ferrite, cementite, and pearlite that accounts for 6.5% or less of the entire microstructure by area fraction. The proportion of the number of cementite grains having an equivalent circle diameter of 0.1 μm or less to the total number of cementite grains is 20% or less, the average cementite grain size is 2.5 μm or less, and the cementite accounts for 1.0% or more and less than 3.5% of the entire microstructure by area fraction. The average concentration of solute B in a region extending from a surface layer to a depth of 100 μm is 10 mass ppm or more. The average concentration of N present as AlN in the region is 70 mass ppm or less.

High-carbon hot-rolled steel sheet and method for manufacturing the same

A steel sheet and a member excellent in cold workability, hardenability, and post-quenching surface layer hardness, and methods for manufacturing the steel sheet and the member. The steel sheet has a specified chemical composition and a microstructure containing ferrite and carbides, a ratio of the volume of ferrite and carbides to the volume of the entire microstructure is 90% or more, a ratio of the volume of proeutectoid ferrite to the volume of the entire microstructure is 20% or more and 80% or less, a Mn concentration in the carbides is 0.10 mass % or more and 0.50 mass % or less, and a ratio of the number of carbides with particle diameters of 1 μm or more to the total number of carbides is 30% or more and 60% or less.

Steel sheet and member, and methods for manufacturing same

A high-carbon hot-rolled steel sheet has a composition containing, on a percent by mass basis, C: 0.10% or more and less than 0.20%, Si: 0.5% or less, Mn: 0.25% to 0.65%, P: 0.03% or less, S: 0.010% or less, sol. Al: 0.10% or less, N: 0.0065% or less, Cr: 0.05% to 0.50%, and B: 0.0005% to 0.005%, the balance being Fe and incidental impurities, the high-carbon hot-rolled steel sheet having a microstructure containing ferrite and cementite, in which the percentage of the number of cementite grains having an equivalent circular diameter of 0.1 &#x3bc;m or less is 12% or less based on the total number of cementite grains, the amount of Cr dissolved in the steel sheet is 0.03% to 0.50%, and the high-carbon hot-rolled steel sheet has a hardness of 73 or less in terms of HRB and a total elongation of 37% or more.

High-carbon hot-rolled steel sheet and method for producing the same

A high-carbon cold rolled steel sheet having a specified chemical composition, and a method for manufacturing the same. The method includes forming a hot rolled steel sheet, performing cooling at an average cooling rate of 30&#xb0; C./s or more and 70&#xb0; C./s or less through a temperature range of a finish rolling end temperature to 660&#xb0; C., coiling a hot rolled steel sheet at a temperature of 500&#xb0; C. or more and 660&#xb0; C. or less, and, optionally, pickling the coiled hot rolled steel sheet, and then performing a first box-annealing of holding at an annealing temperature in a temperature range of 650 to 720&#xb0; C., then performing cold rolling at a rolling reduction ratio of 20 to 50%, and then performing a second box-annealing of holding at an annealing temperature in a temperature range of 650 to 720&#xb0; C.

High-carbon cold rolled steel sheet and method for manufacturing same

Provided are a high-carbon hot-rolled steel sheet with excellent formability and hardenability and a method for manufacturing the same. The high-carbon hot-rolled steel sheet has a composition containing, on a mass basis, C: 0.10% to 0.33%, Si: 0.15% to 0.35%, Mn: 0.5% to 0.9%, P: 0.03% or less, S: 0.010% or less, sol. Al: 0.10% or less, N: 0.0065% or less, and Cr: 0.90% to 1.5%, the remainder being Fe and inevitable impurities, has a microstructure containing ferrite and cementite, a cementite density being 0.25 grains/&#x3bc;mor less, and has a hardness of 110 HV to 160 HV and a total elongation of 40% or more.

A high-carbon hot-rolled steel sheet having a chemical composition containing, by mass %, C: more than 0.40% and 0.63% or less, Si: 0.10% or less, Mn: 0.50% or less, P: 0.03% or less, S: 0.010% or less, sol.Al: 0.10% or less, N: 0.0050% or less, B: 0.0005% or more and 0.0050% or less, and at least one of Sb, Sn, Bi, Ge, Te, and Se in an amount of 0.002% or more and 0.030% or less in total. The steel sheet has a microstructure including ferrite and cementite, in which the density of cementite in ferrite grains is 0.13 pieces/&#x3bc;mor less. Additionally, the steel sheet has a hardness of 81 or less in terms of HRB and a total elongation of 33% or more.

There is provided a high-carbon hot-rolled steel sheet and method for producing the same. The steel sheet has excellent hardenability consistently, even when annealed in a nitrogen atmosphere, and excellent workability. The steel sheet has a hardness in the range of 65 or less in terms of HRB and a total elongation El of 40% or more before a quenching treatment is performed.

There is provided is a high-carbon hot-rolled steel sheet and method for producing the same. The steel sheet has excellent hardenability consistently, even when annealed in a nitrogen atmosphere, and excellent formability. The steel sheet has a hardness in the range of 83 HRB or less and a total elongation of 30% or more before being subjected to a quenching treatment.

A coated steel sheet includes a corrosion-resistant coating composed of at least one layer selected from the group consisting of a Ni layer, a Sn layer, an Fe&#x2014;Ni alloy layer, an Fe&#x2014;Sn alloy layer, and an Fe&#x2014;Ni&#x2014;Sn alloy layer disposed on at least one surface of a steel sheet, and an adhesive coating disposed on the corrosion-resistant coating, the adhesive coating containing Zr and further containing at least one metal element selected from the group consisting of Co, Fe, Ni, V, Cu, Mn, and Zn, in total, at a ratio by mass of 0.01 to 10 with respect to Zr. The coated steel sheet has excellent humid resin adhesion and corrosion resistance, in which streaky surface defects do not occur.

Coated steel sheet, method for producing the same, and resin-coated steel sheet obtained using the same

A high-carbon hot rolled steel sheet with excellent hardenability and small in-plane anisotropy, and a method for manufacturing the steel sheet are provided. The steel sheet has a chemical composition including, by mass %, C: 0.20 to 0.48%, Si: not more than 0.1%, Mn: not more than 0.5%, P: not more than 0.03%, S: not more than 0.01%, sol. Al: not more than 0.10%, N: not more than 0.005% and B: 0.0005 to 0.0050%, the balance including Fe and inevitable impurities. The steel sheet includes a microstructure containing ferrite and cementite. The cementite has an average grain size of not more than 1.0 &#x3bc;m. The steel sheet has an in-plane anisotropy of r value, &#x394;r, of not more than 0.1 in absolute value.

High-carbon hot rolled steel sheet with excellent hardenability and small in-plane anistropy and method for manufacturing the same

A manufacturing method for steel sheets for containers produces steel sheets with excellent film adhesion qualities. This steel sheet for containers has, on a steel sheet, a chemical conversion coating with a metal Zr content of 1-100 mg/m, a P content of 0.1-50 mg/m, and an F content of no more than 0.1 mg/m, upon which is formed a phenolic resin layer with a C content of 0.1-50 mg/m. Moreover, the manufacturing method for steel sheets for containers is a method for obtaining the steel sheet for containers wherein the chemical conversion coating is formed on the steel sheet by subjecting the steel sheet to immersion in or electrolytic treatment with a treatment solution containing Zr ions, phosphoric acid ions, and F ions; and subsequently, the steel sheet upon which the chemical conversion coating has been formed is immersed in, or undergoes topical application of, an aqueous solution containing phenolic resin, then dried.

Method of manufacturing a steel sheet for containers

A steel sheet for containers that has excellent film adhesion qualities, and has; a chemical conversion coating formed by immersing or subjecting to electrolytic treatment a steel sheet in a solution containing Zr ions, F ions, with adhesion amount of 0.1 to 100 mg/mfor metal Zr and no more than 0.1 mg/mfor F; and a hydroxyl acid treatment layer formed on the chemical conversion coating, the layer having a C adhesion amount of 0.05 to 50 mg/m.

Steel sheet for containers and manufacturing method for same

Provided are an apparatus for continuous electrolytic treatment of a steel sheet that is suitable for producing a surface-treated steel sheet and a method for producing the surface-treated steel sheet using the apparatus for continuous electrolytic treatment of a steel sheet. The apparatus includes N pairs of tabular electrodes having a length L and being arranged to respectively face two surfaces of a steel sheet. Each electrode includes n sections arranged in the longitudinal direction of the electrode and disposed on the surface of the electrode facing the steel sheet surface. Each section is constituted by a conductive portion including an electrode portion having a length Tand a nonconductive portion made by making an electrode portion having a length Tnonconductive, where n&#xd7;N&#x2267;10, 0.96&#x2267;T/(T+T)&#x2267;0.05, and 0.9&#x2267;T/L&#x2267;0.1.

Apparatus for continuous electrolytic treatment of steel sheet and method for producing surface-treated steel sheet using the same

A steel sheet for containers that has excellent film adhesion qualities, and has a Zr compound film formed thereupon by immersion in or electrolytic treatment with a solution containing Zr ions, F ions, and hydroxylic acid, the Zr compound film being applied in an amount such that the metal Zr content is 0.1-100 mg/mand the F content is no more than 0.1 mg/m.

A manufacturing method for steel sheets for containers produces steel sheets with excellent film adhesion qualities. In a method for manufacturing steel sheets upon which is formed a chemical conversion coating having a metal Zr content of 1-100 mg/mand F content of no more than 0.1 mg/m, the chemical conversion coating is formed on the steel sheet by subjecting the steel sheet to immersion in or electrolytic treatment with a treatment solution containing Zr ions and F ions, and subsequently, the steel sheet upon which the chemical conversion coating has been formed is washed with water having a temperature of at least 80&#xb0; C. and dried.

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Kawasaki, Japan

Yuka Miyamoto