Patents by Inventor Mai AOYAMA
Mai AOYAMA has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Publication number: 20240026477Abstract: A high-strength galvanized steel sheet is disclosed which has a specified chemical composition, has a steel microstructure including, in terms of area fraction, 35% or more and 80% or less of ferrite, 0.1% or more and less than 5.0% of as-quenched martensite, 3.0% or more and 35% or less of tempered martensite, and 8% or more of retained austenite, in which an average grain diameter of the ferrite is 6 ?m or less, in which an average grain diameter of the retained austenite is 3 ?m or less, in which a value calculated by dividing an average Mn content (mass %) in the retained austenite by an average Mn content (mass %) in the ferrite is 1.5 or more.Type: ApplicationFiled: January 10, 2020Publication date: January 25, 2024Applicant: JFE Steel CorporationInventors: Kazuki Endoh, Yoshiyasu Kawasaki, Yuki Toji, Yoshimasa Funakawa, Mai Aoyama
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Publication number: 20240009962Abstract: To provide an Fe-based electroplated steel sheet that not only has excellent chemical convertibility or excellent coating appearance when subjected to hot-dip galvanizing, but also has excellent resistance to cracking in resistance welding. Disclosed is an Fe-based plated steel sheet including: a cold-rolled steel sheet having a chemical composition containing Si in an amount of 0.1 mass % or more and 3.0 mass % or less; and an Fe-based electroplating layer formed on one or both surfaces of the cold-rolled steel sheet with a coating weight per surface of 1.0 g/m2 or more, in which a thickness of an internal oxidation layer is 2.00 ?m or less, and an average value of C concentration in a range of 10 ?m to 20 ?m in a thickness direction from the surface of the Fe-based electroplating layer is 0.10 mass % or less.Type: ApplicationFiled: November 5, 2021Publication date: January 11, 2024Applicant: JFE STEEL CORPORATIONInventors: Shunsuke YAMAMOTO, Yusuke OKUMURA, Katsutoshi TAKASHIMA, Mai AOYAMA, Tomomi KANAZAWA, Katsuya HOSHINO, Yoichi MAKIMIZU, Takashi KAWANO, Takako YAMASHITA, Hiroshi MATSUDA
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Publication number: 20230407447Abstract: Provided is a galvanized steel sheet with excellent resistance to cracking in resistance welding at a welded portion, even if crystal orientations of an Fe-based electroplating layer and a cold-rolled steel sheet are integrated at a high ratio at the interface between the Fe-based electroplating layer and the cold-rolled steel sheet. The galvanized steel sheet has a Si-containing cold-rolled steel sheet containing Si in an amount of 0.1 mass % to 3.0 mass %; an Fe-based electroplating layer formed on at least one surface of the Si-containing cold-rolled steel sheet with a coating weight per surface of more than 20.0 g/m2, and a galvanized layer formed on the Fe-based electroplating layer, where crystal orientations of the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet are integrated at a ratio of more than 50 % at the interface between the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet.Type: ApplicationFiled: November 5, 2021Publication date: December 21, 2023Applicant: JFE STEEL CORPORATIONInventors: Shunsuke YAMAMOTO, Katsutoshi TAKASHIMA, Mai AOYAMA, Yusuke OKUMURA, Tomomi KANAZAWA, Katsuya HOSHINO, Hiroshi MATSUDA, Ei OKUMURA, Yoichi MAKIMIZU, Masaki KOBA
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Publication number: 20230407506Abstract: Provided is a steel sheet with excellent resistance to cracking in resistance welding at a welded portion, even if the crystal orientations of an Fe-based electroplating layer and a Si-containing cold-rolled steel sheet are integrated at a high ratio at the interface between the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet. Provided is an Fe-based electroplated steel sheet having a Si-containing cold-rolled steel sheet containing Si in an amount of 0.1 mass % or more and 3.0 mass % or less; and an Fe-based electroplating layer formed on at least one surface of the Si-containing cold-rolled steel sheet with a coating weight per surface of more than 20.0 g/m2, where the crystal orientations of the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet are integrated at a ratio of more than 50% at the interface between the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet.Type: ApplicationFiled: November 5, 2021Publication date: December 21, 2023Applicant: JFE STEEL CORPORATIONInventors: Shunsuke YAMAMOTO, Katsutoshi TAKASHIMA, Mai AOYAMA, Yusuke OKUMURA, Tomomi KANAZAWA, Katsuya HOSHINO, Hiroshi MATSUDA, Ei OKUMURA, Yoichi MAKIMIZU, Masaki KOBA
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Publication number: 20230407485Abstract: Provided is an alloyed galvanized steel sheet with excellent resistance to cracking in resistance welding at a welded portion, even if crystal orientations of an Fe-based electroplating layer and a cold-rolled steel sheet are integrated at a high ratio at the interface between the Fe-based electroplating layer and the cold-rolled steel sheet. The alloyed galvanized steel sheet has a Si-containing cold-rolled steel sheet containing Si in an amount of 0.1 mass % to 3.0 mass %; an Fe-based electroplating layer formed on at least one surface of the Si-containing cold-rolled steel sheet with a coating weight per surface exceeding 20.0 g/m2, and an alloyed galvanized layer formed on the Fe-based electroplating layer, where crystal orientations of the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet are integrated at a ratio of more than 50% at the interface between the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet.Type: ApplicationFiled: November 5, 2021Publication date: December 21, 2023Applicant: JFE STEEL CORPORATIONInventors: Shunsuke YAMAMOTO, Katsutoshi TAKASHIMA, Mai AOYAMA, Yusuke OKUMURA, Tomomi KANAZAWA, Katsuya HOSHINO, Hiroshi MATSUDA, Ei OKUMURA, Yoichi MAKIMIZU, Masaki KOBA
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Patent number: 11814695Abstract: A high-strength galvanized steel sheet and a method for producing the steel sheet. The steel sheet has a composition that includes C: 0.030% to 0.250%, Si: 0.01% to 3.00%, Mn: 2.00% to 10.00%, P: 0.001% to 0.100%, S: 0.0001% to 0.0200%, N: 0.0005% to 0.0100%, Ti: 0.005% to 0.200%, on a mass basis, and Fe and inevitable impurities. Additionally, the steel sheet has concentration of solute Mn at a depth of 5 ?m or less from a surface of the steel sheet that is 1.50% by mass or less, and a value obtained by dividing the average mass percentage of Mn in retained austenite by the average mass percentage of Mn in ferrite is 2.0 or more.Type: GrantFiled: November 8, 2016Date of Patent: November 14, 2023Assignee: JFE STEEL CORPORATIONInventors: Mai Aoyama, Minoru Tanaka, Yoshitsugu Suzuki, Yoshiyasu Kawasaki, Hideyuki Takahashi
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Patent number: 11788163Abstract: A high-strength steel sheet includes a steel structure with: ferrite being 35% to 80% and tempered martensite being greater than 5% and 20% or less in terms of area fraction; retained austenite being 8% or more in terms of volume fraction; an average grain size of: the ferrite being 6 ?m or less; and the retained austenite being 3 ?m or less; a value obtained by dividing an area fraction of blocky austenite by a sum of area fractions of lath-like austenite and the blocky austenite being 0.6 or more; a value obtained by dividing, by mass %, an average Mn content in the retained austenite by an average Mn content in the ferrite being 1.5 or more; and a value obtained by dividing, by mass %, an average C content in the retained austenite by an average C content in the ferrite being 3.0 or more.Type: GrantFiled: March 20, 2019Date of Patent: October 17, 2023Assignee: JFE STEEL CORPORATIONInventors: Kazuki Endo, Yoshiyasu Kawasaki, Yuki Toji, Yoshimasa Funakawa, Mai Aoyama
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Publication number: 20230287534Abstract: Provided are a high-strength electrogalvannealed steel sheet that has a TS of 780 MPa or higher and a method for manufacturing the high-strength electrogalvannealed steel sheet. The high-strength electrogalvannealed steel sheet has a composition including, in terms of % by mass, C: 0.030% or more and 0.250% or less, Si: 0.01% or more and 3.00% or less, Mn: 1.00% or more and 10.00% or less, P: 0.001% or more and 0.100% or less, and S: 0.0001% or more and 0.0200% or less, with the balance being Fe and unavoidable impurities. The steel sheet has an electrogalvannealed coating layer on a surface thereof. The electrogalvannealed coating layer has an Fe content of 8.0% to 15.0%. The steel sheet has a tensile strength of 780 MPa or higher. The steel sheet has a diffusible hydrogen content of 0.2 wt. ppm or less.Type: ApplicationFiled: May 19, 2023Publication date: September 14, 2023Applicant: JFE Steel CorporationInventors: Mai Aoyama, Kazuaki Tsuchimoto, Yusuke Fushiwaki
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Patent number: 11661642Abstract: A high-strength steel sheet includes a steel structure with: ferrite being 35% to 80%, martensite being 5% to 35%, and tempered martensite being 0% to 5% in terms of area fraction; retained austenite being 8% or more in terms of volume fraction; an average grain size of: the ferrite being 6 ?m or less; and the retained austenite being 3 ?m or less; a value obtained by dividing an area fraction of blocky austenite by a sum of area fractions of lath-like austenite and the blocky austenite being 0.6 or more; a value obtained by dividing, by mass %, an average Mn content in the retained austenite by an average Mn content in the ferrite being 1.5 or more; and a value obtained by dividing, by mass %, an average C content in the retained austenite by an average C content in the ferrite being 3.0 or more.Type: GrantFiled: March 20, 2019Date of Patent: May 30, 2023Assignee: JFE STEEL CORPORATIONInventors: Kazuki Endo, Yoshiyasu Kawasaki, Yuki Toji, Yoshimasa Funakawa, Mai Aoyama
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Patent number: 11643700Abstract: A high-strength steel includes a steel structure with: in area fraction, 60.0% to less than 90.0% of ferrite, 0% to less than 5.0% of unrecrystallized ferrite, 2.0% to 25.0% of martensite, 0% to 5.0% of carbide, and 0% to 3.0% of bainite; in volume fraction, more than 7.0% of retained austenite; in a cross-sectional view of 100 ?m×100 ?m, a value obtained by dividing number of retained austenite that are not adjacent to retained austenite whose crystal orientations are different by a total number of retained austenite being less than 0.80, an average crystal grain size of the ferrite being 6.0 ?m or less, an average crystal grain size of the retained austenite being 3.0 ?m or less, and a value obtained by dividing, by mass %, an average content of Mn in the retained austenite by an average content of Mn in steel being 1.50 or more.Type: GrantFiled: March 20, 2019Date of Patent: May 9, 2023Assignee: JFE STEEL CORPORATIONInventors: Yoshiyasu Kawasaki, Kazuki Endo, Yuki Toji, Yoshimasa Funakawa, Satoshi Maeda, Mai Aoyama
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Patent number: 11643702Abstract: A method for producing a high-strength hot-dip galvannealed steel sheet, in which a high-strength steel sheet is used as a base material, includes a rolling step (x) of rolling a hot-dip galvannealed steel sheet with a coating layer having an Fe concentration of 8% to 17% by mass, and a heat treatment step (y) of heating the coated steel sheet which has been subjected to the rolling step (x) under the conditions satisfying the following formulae (1) and (2): (273+T)×(20+2×log10(t))?8000??(1) 40?T?160??(2) where T: heating temperature (° C.) of the coated steel sheet, and t: holding time (hr) at the heating temperature T.Type: GrantFiled: October 1, 2021Date of Patent: May 9, 2023Assignee: JFE Steel CorporationInventors: Satoshi Maeda, Yoshiyasu Kawasaki, Yusuke Fushiwaki, Mai Aoyama
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Patent number: 11597983Abstract: A method for producing a high-strength hot-dip galvannealed steel sheet, in which a high-strength steel sheet is used as a base material, includes a rolling step (x) of rolling a hot-dip galvannealed steel sheet with a coating layer having an Fe concentration of 8% to 17% by mass, and a heat treatment step (y) of heating the coated steel sheet which has been subjected to the rolling step (x) under the conditions satisfying the following formulae (1) and (2): (273+T)×(20+2×log10(t))?8000??(1) 40?T?160??(2) where T: heating temperature (° C.) of the coated steel sheet, and t: holding time (hr) at the heating temperature T.Type: GrantFiled: March 26, 2019Date of Patent: March 7, 2023Assignee: JFE Steel CorporationInventors: Satoshi Maeda, Yoshiyasu Kawasaki, Yusuke Fushiwaki, Mai Aoyama
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Publication number: 20220186334Abstract: An object is to provide a high strength steel sheet having a TS (tensile strength) of 980 MPa or more and excellent formability and a method for manufacturing the steel sheet. A high strength steel sheet which is excellent in terms of formability, which is manufactured under optimized manufacturing conditions, and which has a predetermined chemical composition and a steel microstructure including, in terms of area fraction, 35% or more and 80% or less of ferrite, 5% or more and 35% or less of as-quenched martensite, 0.1% or more and less than 3.0% of tempered martensite, and 8% or more of retained austenite, in which the average grain size of the ferrite is 6 ?m or less, in which the average grain size of the retained austenite is 3 ?m or less, in which a value calculated by dividing the average Mn content in the retained austenite by the average Mn content in the ferrite is 1.Type: ApplicationFiled: December 10, 2019Publication date: June 16, 2022Applicant: JFE STEEL CORPORATIONInventors: Kazuki ENDOH, Yoshiyasu KAWASAKI, Yuki TOJI, Yoshimasa FUNAKAWA, Mai AOYAMA
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Publication number: 20220017986Abstract: A method for producing a high-strength hot-dip galvannealed steel sheet, in which a high-strength steel sheet is used as a base material, includes a rolling step (x) of rolling a hot-dip galvannealed steel sheet with a coating layer having an Fe concentration of 8% to 17% by mass, and a heat treatment step (y) of heating the coated steel sheet which has been subjected to the rolling step (x) under the conditions satisfying the following formulae (1) and (2): (273+T)×(20+2×log10(t))?8000??(1) 40?T?160??(2) where T: heating temperature (° C.) of the coated steel sheet, and t: holding time (hr) at the heating temperature T.Type: ApplicationFiled: October 1, 2021Publication date: January 20, 2022Applicant: JFE Steel CorporationInventors: Satoshi Maeda, Yoshiyasu Kawasaki, Yusuke Fushiwaki, Mai Aoyama
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Publication number: 20210115541Abstract: A high-strength steel sheet includes a steel structure with: ferrite being 35% to 80%, martensite being 5% to 35%, and tempered martensite being 0% to 5% in terms of area fraction; retained austenite being 8% or more in terms of volume fraction; an average grain size of: the ferrite being 6 ?m or less; and the retained austenite being 3 ?m or less; a value obtained by dividing an area fraction of blocky austenite by a sum of area fractions of lath-like austenite and the blocky austenite being 0.6 or more; a value obtained by dividing, by mass %, an average Mn content in the retained austenite by an average Mn content in the ferrite being 1.5 or more; and a value obtained by dividing, by mass %, an average C content in the retained austenite by an average C content in the ferrite being 3.0 or more.Type: ApplicationFiled: March 20, 2019Publication date: April 22, 2021Applicant: JFE STEEL CORPORATIONInventors: Kazuki ENDO, Yoshiyasu KAWASAKI, Yuki TOJI, Yoshimasa FUNAKAWA, Mai AOYAMA
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Publication number: 20210108282Abstract: A high-strength steel includes a steel structure with: in area fraction, 60.0% to less than 90.0% of ferrite, 0% to less than 5.0% of unrecrystallized ferrite, 2.0% to 25.0% of martensite, 0% to 5.0% of carbide, and 0% to 3.0% of bainite; in volume fraction, more than 7.0% of retained austenite; in a cross-sectional view of 100 ?m×100 ?m, a value obtained by dividing number of retained austenite that are not adjacent to retained austenite whose crystal orientations are different by a total number of retained austenite being less than 0.80, an average crystal grain size of the ferrite being 6.0 ?m or less, an average crystal grain size of the retained austenite being 3.0 ?m or less, and a value obtained by dividing, by mass %, an average content of Mn in the retained austenite by an average content of Mn in steel being 1.50 or more.Type: ApplicationFiled: March 20, 2019Publication date: April 15, 2021Applicant: JFE STEEL CORPORATIONInventors: Yoshiyasu KAWASAKI, Kazuki ENDO, Yuki TOJI, Yoshimasa FUNAKAWA, Satoshi MAEDA, Mai AOYAMA
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Publication number: 20210010100Abstract: A method for producing a high-strength hot-dip galvannealed steel sheet, in which a high-strength steel sheet is used as a base material, includes a rolling step (x) of rolling a hot-dip galvannealed steel sheet with a coating layer having an Fe concentration of 8% to 17% by mass, and a heat treatment step (y) of heating the coated steel sheet which has been subjected to the rolling step (x) under the conditions satisfying the following formulae (1) and (2): (273+T)×(20+2×log10(t))?8000 ??(1) 40?T?160 ??(2) where T: heating temperature (° C.) of the coated steel sheet, and t: holding time (hr) at the heating temperature T.Type: ApplicationFiled: March 26, 2019Publication date: January 14, 2021Applicant: JFE Steel CorporationInventors: Satoshi Maeda, Yoshiyasu Kawasaki, Yusuke Fushiwaki, Mai Aoyama
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Publication number: 20210010101Abstract: A high-strength steel sheet includes a steel structure with: ferrite being 35% to 80% and tempered martensite being greater than 5% and 20% or less in terms of area fraction; retained austenite being 8% or more in terms of volume fraction; an average grain size of: the ferrite being 6 ?m or less; and the retained austenite being 3 ?m or less; a value obtained by dividing an area fraction of blocky austenite by a sum of area fractions of lath-like austenite and the blocky austenite being 0.6 or more; a value obtained by dividing, by mass %, an average Mn content in the retained austenite by an average Mn content in the ferrite being 1.5 or more; and a value obtained by dividing, by mass %, an average C content in the retained austenite by an average C content in the ferrite being 3.0 or more.Type: ApplicationFiled: March 20, 2019Publication date: January 14, 2021Applicant: JFE STEEL CORPORATIONInventors: Kazuki ENDO, Yoshiyasu KAWASAKI, Yuki TOJI, Yoshimasa FUNAKAWA, Mai AOYAMA
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Publication number: 20200347479Abstract: Provided are a high-strength electrogalvannealed steel sheet that has a TS of 780 MPa or higher and a method for manufacturing the high-strength electrogalvannealed steel sheet. The high-strength electrogalvannealed steel sheet has a composition including, in terms of % by mass, C: 0.030% or more and 0.250% or less, Si: 0.01% or more and 3.00% or less, Mn: 1.00% or more and 10.00% or less, P: 0.001% or more and 0.100% or less, and S: 0.0001% or more and 0.0200% or less, with the balance being Fe and unavoidable impurities. The steel sheet has an electrogalvannealed coating layer on a surface thereof. The electrogalvannealed coating layer has an Fe content of 8.0% to 15.0%. The steel sheet has a tensile strength of 780 MPa or higher. The steel sheet has a diffusible hydrogen content of 0.2 wt. ppm or less.Type: ApplicationFiled: December 13, 2018Publication date: November 5, 2020Applicant: JFE Steel CorporationInventors: Mai Aoyama, Kazuaki Tsuchimoto, Yusuke Fushiwaki
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Patent number: 10704117Abstract: Provided are a cold-rolled steel sheet which can preferably be used for manufacturing a high-strength galvanized steel sheet and methods for manufacturing the steel sheets. The cold-rolled steel sheet has a specified chemical composition, in which the Mn concentration in a surface layer of the steel sheet satisfies relational expression (1) and relational expression (2) below. 8?(Cp/Cc)×Mn . . . (1) (Cmin/Cc)×Mn?2.5 . . . (2) where Cp: maximum Mn concentration in a region within 0.5 ?m of the surface of a steel sheet in the thickness direction; Cc: average Mn concentration in a region from a position located 5 ?m from a surface of a steel sheet in the thickness direction to a position located 5 ?m from an opposite surface in the thickness direction; Cmin: minimum Mn concentration in a region from 0.5 ?m to 5 ?m from the surface of a steel sheet in the thickness direction; and Mn: Mn content (mass %).Type: GrantFiled: July 28, 2016Date of Patent: July 7, 2020Assignee: JFE Steel CorporationInventors: Kenji Kawamura, Noriaki Kohsaka, Yoshimasa Funakawa, Mai Aoyama, Yoshitsugu Suzuki