Patents by Inventor Yusuke HIRATSUKA
Yusuke HIRATSUKA 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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Patent number: 11332817Abstract: A machine component includes a core made up of a steel for machine structural use, and a medium carbon-containing layer and a high carbon-containing layer formed of the steel for machine structural use, the medium carbon-containing layer covering the core, the high carbon-containing layer covering the medium carbon-containing layer and having a carbon concentration of 0.8-1.5%. The high carbon-containing layer is made up of a martensitic structure having carbides dispersed therein and a residual austenitic structure, wherein spheroidized carbides with an aspect ratio of 1.5 or less constitute 90% or more of a total number of the carbides, and the number of spheroidized carbides on prior austenite grain boundaries is 40% or less of the total number of the carbides.Type: GrantFiled: May 10, 2019Date of Patent: May 17, 2022Assignee: KOMATSU LTD.Inventors: Kensuke Sato, Koji Yamamoto, Yusuke Hiratsuka, Kazuya Hashimoto
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Patent number: 11326220Abstract: A method for producing a machine component excellent in pitting resistance characteristics and toughness includes a carburizing step, performed on a steel material containing 0.13-0.30% C and 0.90-2.00% Cr in mass % and at least one of Si, Mn, Ni, Mo, Nb, V, Ti, B, Al, and N, balance Fe and unavoidable impurities; heating the material to 850-1030° C. to attain carbon concentration in a surface of 0.8-1.5%; cooling the material at an average rate of 5° C./sec or lower from a temperature higher than the Acm point of a surface layer to a cooling end temperature that is at least 50° C. lower than the A1 point to cause the surface layer to have a pearlite or bainite structure with dispersion; spheroidizing annealing at a temperature not higher than the Acm point at the surface layer; heating the material to not higher than the Acm point at the surface layer; and performing tempering.Type: GrantFiled: May 10, 2019Date of Patent: May 10, 2022Assignee: KOMATSU LTD.Inventors: Kensuke Sato, Koji Yamamoto, Yusuke Hiratsuka, Kazuya Hashimoto
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Patent number: 11203803Abstract: A steel with high hardness and excellent toughness contains, in mass %, 0.55-1.10% C, 0.10-2.00% Si, 0.10-2.00% Mn, 0.030% or less P, 0.030% or less S, 1.10-2.50% Cr, and 0.010-0.10% Al, with the balance consisting of Fe and unavoidable impurities. The structure of the steel after quenching is a dual phase structure of martensitic structure and spheroidized carbide. Spheroidized cementite particles with an aspect ratio of 1.5 or less constitute at least 90% of all cementite particles. The proportion of the number of spheroidized cementite particles on the prior austenite grain boundaries to a total number of cementite particles is 20% or less.Type: GrantFiled: September 16, 2016Date of Patent: December 21, 2021Assignees: OSAKA UNIVERSITY, KOMATSU LTD.Inventors: Yoritoshi Minamino, Takemori Takayama, Koji Yamamoto, Yusuke Hiratsuka
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Patent number: 11162162Abstract: A steel with high hardness and excellent toughness contains, in mass %, 0.40-1.00% C, 0.10-2.00% Si, 0.10-1.00% Mn, 0.030% or less P, 0.030% or less S, 1.10-3.20% Cr, 0.010-0.10% Al, and 0.15-0.50% V, and further contains at least one or two of 2.50% or less Ni and 1.00% or less Mo, with an amount of (C+V) being 0.60% or more in mass %, with the balance consisting of Fe and unavoidable impurities. The steel has a microstructure which is a martensitic structure with finely dispersed Fe-based ? carbides, with its prior austenite grain size being 20 ?m or less.Type: GrantFiled: August 8, 2018Date of Patent: November 2, 2021Assignees: OSAKA UNIVERSITY, KOMATSU LTD.Inventors: Yoritoshi Minamino, Koji Hagihara, Koji Yamamoto, Shohei Ikurumi, Yusuke Hiratsuka, Takeshi Fujimatsu, Toshiyuki Sugimoto
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Publication number: 20210032737Abstract: A machine component includes a core made up of a steel for machine structural use, and a medium carbon-containing layer and a high carbon-containing layer formed of the steel for machine structural use, the medium carbon-containing layer covering the core, the high carbon-containing layer covering the medium carbon-containing layer and having a carbon concentration of 0.8-1.5%. The high carbon-containing layer is made up of a martensitic structure having carbides dispersed therein and a residual austenitic structure, wherein spheroidized carbides with an aspect ratio of 1.5 or less constitute 90% or more of a total number of the carbides, and the number of spheroidized carbides on prior austenite grain boundaries is 40% or less of the total number of the carbides.Type: ApplicationFiled: May 10, 2019Publication date: February 4, 2021Applicant: KOMATSU LTD.Inventors: Kensuke SATO, Koji YAMAMOTO, Yusuke HIRATSUKA, Kazuya HASHIMOTO
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Publication number: 20210032716Abstract: A method for producing a machine component excellent in pitting resistance characteristics and toughness includes a carburizing step, performed on a steel material containing 0.13-0.30% C and 0.90-2.00% Cr in mass % and at least one of Si, Mn, Ni, Mo, Nb, V, Ti, B, Al, and N, balance Fe and unavoidable impurities; heating the material to 850-1030° C. to attain carbon concentration in a surface of 0.8-1.5%; cooling the material at an average rate of 5° C./sec or lower from a temperature higher than the Acm point of a surface layer to a cooling end temperature that is at least 50° C. lower than the A1 point to cause the surface layer to have a pearlite or bainite structure with dispersion; spheroidizing annealing at a temperature not higher than the Acm point at the surface layer; heating the material to not higher than the Acm point at the surface layer; and performing tempering.Type: ApplicationFiled: May 10, 2019Publication date: February 4, 2021Applicant: KOMATSU LTD.Inventors: Kensuke SATO, Koji YAMAMOTO, Yusuke HIRATSUKA, Kazuya HASHIMOTO
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Publication number: 20200165710Abstract: A steel with high hardness and excellent toughness contains, in mass %, 0.55-1.10% C, 0.10-2.00% Si, 0.10-2.00% Mn, 0.030% or less P, 0.030% or less S, 1.10-2.50% Cr, and 0.010-0.10% Al, with the balance consisting of Fe and unavoidable impurities. The structure of the steel after quenching is a dual phase structure of martensitic structure and spheroidized carbide. Spheroidized cementite particles with an aspect ratio of 1.5 or less constitute at least 90% of all cementite particles. The proportion of the number of spheroidized cementite particles on the prior austenite grain boundaries to a total number of cementite particles is 20% or less.Type: ApplicationFiled: September 16, 2016Publication date: May 28, 2020Applicants: OSAKA UNIVERSITY, KOMATSU LTD.Inventors: Yoritoshi MINAMINO, Takemori TAKAYAMA, Koji YAMAMOTO, Yusuke HIRATSUKA
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Publication number: 20200080180Abstract: A steel with high hardness and excellent toughness contains, in mass %, 0.40-1.00% C, 0.10-2.00% Si, 0.10-1.00% Mn, 0.030% or less P, 0.030% or less S, 1.10-3.20% Cr, 0.010-0.10% Al, and 0.15-0.50% V, and further contains at least one or two of 2.50% or less Ni and 1.00% or less Mo, with an amount of (C+V) being 0.60% or more in mass %, with the balance consisting of Fe and unavoidable impurities. The steel has a microstructure which is a martensitic structure with finely dispersed Fe-based ? carbides, with its prior austenite grain size being 20 ?m or less.Type: ApplicationFiled: August 8, 2018Publication date: March 12, 2020Applicants: OSAKA UNIVERSITY, KOMATSU LTD.Inventors: Yoritoshi MINAMINO, Koji HAGIHARA, Koji YAMAMOTO, Shohei IKURUMI, Yusuke HIRATSUKA, Takeshi FUJIMATSU, Toshiyuki SUGIMOTO