Patents by Inventor Hiroaki Tahira
Hiroaki Tahira 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: 11827963Abstract: Provided are a roughly-shaped steel material for a nitrided part, and a nitrided part obtained by nitriding the roughly-shaped steel material for a nitrided part, having a determined chemical composition, in which the portion with a diameter or width ranging from 60 to 130 mm of the roughly-shaped steel material for a nitrided part has a microstructure at a depth of 14.5 mm from a surface including, in terms of area fraction: tempered martensite and tempered bainite in total: from 70 to 100%; remaining austenite: from 0 to 5%; and a balance: ferrite and perlite; and has a microstructure at a depth of 15 mm or more from the surface including, in terms of area fraction: tempered martensite and tempered bainite in total: from 0 to less than 50%; remaining austenite: from 0 to 5%; and a balance: ferrite and perlite.Type: GrantFiled: October 29, 2019Date of Patent: November 28, 2023Assignee: NIPPON STEEL CORPORATIONInventors: Masato Yuya, Hiroaki Tahira, Kison Nishihara, Satoru Okawa
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Publication number: 20220177991Abstract: The steel shaft component consists of C: 0.40 to 0.60%, Si: 0.05 to 1.00%, Mn: 1.00 to 2.00%, P: 0.030% or less, S: 0.005 to 0.100%, Cr: 0.10 to 0.50%, V: 0.10 to 0.30%, Al: 0.005 to 0.050%, N: 0.0050 to 0.0200%, Ti: 0 to 0.050%, and the balance: Fe and impurities. A Vickers hardness Hs of the surface of the shaft part is 620 HV or more. A Vickers hardness Hb at an R/2 position satisfies Formula (1). A depth of the hardened layer Hr (mm) having a Vickers hardness of 620 HV or more satisfies Formula (2). The microstructure at the R/2 position is composed of ferrite and pearlite. Within the hardened layer, the number of density of V-containing precipitates having an equivalent circular diameter of more than 100 nm is 10 particles/276 ?m2 or less. Hs/2.3?Hb?350??(1) 0.05?Hr/R?0.Type: ApplicationFiled: April 9, 2020Publication date: June 9, 2022Inventors: Kison NISHIHARA, Hiroaki TAHIRA, Yoko SUEYASU
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Patent number: 11261511Abstract: A hot forged steel material in the present embodiment includes a chemical composition that consists of, in mass %, C: 0.14 to 0.20%, Si: 0.20 to 1.00%, Mn: 1.00 to 1.90%, P: 0.030% or less, S: 0.030% or less, V: 0.16 to 0.30%, Al: 0.015 to 0.050%, N: 0.0050 to 0.0250%, Cr: 0.10 to 0.30%, Cu: 0 to 0.10%, and Nb: 0 to 0.10%, with the balance being Fe and impurities, and that satisfies Formula (1) and Formula (2), wherein a grain size number of ferrite in the steel is 9.0 or more, and an absorbed energy at ?30° C. is 100 J or more in the Charpy impact test using a V notch specimen. 0.36?C+(Si+Mn)/6+(Cr+V)/5+Cu/15<0.68??(1) 51/12×C?V?0.Type: GrantFiled: October 31, 2018Date of Patent: March 1, 2022Assignee: NIPPON STEEL CORPORATIONInventors: Yoko Sueyasu, Hiroaki Tahira, Ken Yoshino, Kison Nishihara
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Publication number: 20220010416Abstract: Provided are a roughly-shaped steel material for a nitrided part, and a nitrided part obtained by nitriding the roughly-shaped steel material for a nitrided part, having a determined chemical composition, in which the portion with a diameter or width ranging from 60 to 130 mm of the roughly-shaped steel material for a nitrided part has a microstructure at a depth of 14.5 mm from a surface including, in terms of area fraction: tempered martensite and tempered bainite in total: from 70 to 100%; remaining austenite: from 0 to 5%; and a balance: ferrite and perlite; and has a microstructure at a depth of 15 mm or more from the surface including, in terms of area fraction: tempered martensite and tempered bainite in total: from 0 to less than 50%; remaining austenite: from 0 to 5%; and a balance: ferrite and perlite.Type: ApplicationFiled: October 29, 2019Publication date: January 13, 2022Inventors: Masato YUYA, Hiroaki TAHIRA, Kison NISHIHARA, Satoru OKAWA
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Publication number: 20210189532Abstract: A hot forged steel material in the present embodiment includes a chemical composition that consists of, in mass %, C: 0.14 to 0.20%, Si: 0.20 to 1.00%, Mn: 1.00 to 1.90%, P: 0.030% or less, S: 0.030% or less, V: 0.16 to 0.30%, Al: 0.015 to 0.050%, N: 0.0050 to 0.0250%, Cr: 0.10 to 0.30%, Cu: 0 to 0.10%, and Nb: 0 to 0.10%, with the balance being Fe and impurities, and that satisfies Formula (1) and Formula (2), wherein a grain size number of ferrite in the steel is 9.0 or more, and an absorbed energy at ?30° C. is 100 J or more in the Charpy impact test using a V notch specimen. 0.36?C+(Si+Mn)/6+(Cr+V)/5+Cu/15<0.68??(1) 51/12×C?V?0.Type: ApplicationFiled: October 31, 2018Publication date: June 24, 2021Inventors: Yoko SUEYASU, Hiroaki TAHIRA, Ken YOSHINO, Kison NISHIHARA
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Patent number: 10975452Abstract: There is provided a hot forged product having excellent wear resistance and fatigue strength even when the hot forged product is produced with a thermal refining treatment and a case hardening thermal treatment after hot forging omitted, and having a chemical composition consisting of, in mass %, C: 0.45 to 0.70%, Si: 0.01 to 0.70%, Mn: 1.0 to 1.7%, S: 0.01 to 0.1%, Cr: 0.05 to 0.25%, Al: 0.003 to 0.050%, N: 0.003 to 0.02% with the balance being Fe and impurities. The matrix at the depth of 500 ?m to 5 mm from an unmachined surface of the forged product is a ferrite-pearlite structure, in which a pro-eutectoid ferrite area fraction is 3% or less or a pearlite structure, and the average diameter of pearlite colonies in the pearlite structure at the depth of 500 ?m to 5 mm from the unmachined surface is 5.0 ?m or less.Type: GrantFiled: May 20, 2016Date of Patent: April 13, 2021Assignee: NIPPON STEEL CORPORATIONInventors: Kison Nishihara, Yoshiyuki Kashiwara, Hiroaki Tahira
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Publication number: 20190127817Abstract: There is provided a hot forged product having excellent wear resistance and fatigue strength even when the hot forged product is produced with a thermal refining treatment and a case hardening thermal treatment after hot forging omitted, and having a chemical composition consisting of, in mass %, C: 0.45 to 0.70%, Si: 0.01 to 0.70%, Mn: 1.0 to 1.7%, S: 0.01 to 0.1%, Cr: 0.05 to 0.25%, Al: 0.003 to 0.050%, N: 0.003 to 0.02% with the balance being Fe and impurities. The matrix at the depth of 500 ?m to 5 mm from an unmachined surface of the forged product is a ferrite-pearlite structure, in which a pro-eutectoid ferrite area fraction is 3% or less or a pearlite structure, and the average diameter of pearlite colonies in the pearlite structure at the depth of 500 ?m to 5 mm from the unmachined surface is 5.0 ?m or less.Type: ApplicationFiled: May 20, 2016Publication date: May 2, 2019Applicant: Nippon Steel & Sumitomo Metal CorporationInventors: Kison NISHIHARA, Yoshiyuki KASHIWARA, Hiroaki TAHIRA
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Patent number: 9731341Abstract: A forged crankshaft (1) includes a carbon steel containing S, wherein in a portion corresponding to a machined outer circumferential surface of a shaft part such as journals (J), crank pins (P), a front part (Fr), and a flange (Fl), a ratio x/y of an area rate x of sulfide in a position (X) corresponding to a parting surface of a die for finish forging to an area rate y of sulfide in a position (Y) corresponding to a bottom of a die impression of the die for finish forging is equal to or lower than 1.5. The forged crankshaft (1) can avoid an occurrence of machined surface cracks on the journals (J) and the crank pins (P) after the outer circumferential surface is machined.Type: GrantFiled: December 9, 2013Date of Patent: August 15, 2017Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Hiroaki Tahira, Kisung Kim, Junichi Okubo
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Patent number: 9239075Abstract: To provide a forged crankshaft having an excellent wear resistance. The forged crankshaft according to the present embodiment includes a non-heat treated steel material. The non-heat treated steel material has a chemical composition which contains, by mass %, C: 0.45 to 0.70%, Si: 0.75 to 1.30%, Mn: 1.00 to 2.00%, S: 0.03 to 0.30%, Cr: 0.05 to 0.30%, Al: 0.005 to 0.050%, and N: 0.005 to 0.020%, the balance being Fe and impurities, and satisfies the following Formula (1): 1.1C+Mn+0.2Cr>2.0??(1) where a symbol of each element in Formula (1) is substituted by the content (mass %) of the each element. A matrix of the non-heat treated steel material is a ferrite-pearlite microstructure in which an area ratio of pro-eutectoid ferrite is less than 10% or a pearlite microstructure.Type: GrantFiled: June 13, 2011Date of Patent: January 19, 2016Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Kisung Kim, Hiroaki Tahira, Taketo Maejima
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Patent number: 9234265Abstract: There is provided a steel for induction hardening in which cracks are less liable to occur and high hardness and seizure resistance are attained even if a tempering process after induction hardening is omitted. The steel for induction hardening according to the present invention contains, by mass percent, C: 0.20 to 0.34%, Si: at most 0.20%, Mn: 0.75 to 2.0%, P: at most 0.03%, S: at most 0.20%, Cr: 0.05 to 1.2%, Ti: at least 0.002% and less than 0.030%, Al: 0.005 to 0.04%, and N: 0.0040 to 0.020%, the balance being Fe and impurities, and satisfies Formula (1): 1.20?Mn+Cr?2.10??(1) where the content (mass %) of each element is substituted for each of the symbols of elements in Formula (1).Type: GrantFiled: June 27, 2011Date of Patent: January 12, 2016Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Yuta Mizobe, Hiroaki Tahira, Ken Yoshino
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Publication number: 20150321245Abstract: A forged crankshaft (1) includes a carbon steel containing S, wherein in a portion corresponding to a machined outer circumferential surface of a shaft part such as journals (J), crank pins (P), a front part (Fr), and a flange (Fl), a ratio x/y of an area rate x of sulfide in a position (X) corresponding to a parting surface of a die for finish forging to an area rate y of sulfide in a position (Y) corresponding to a bottom of a die impression of the die for finish forging is equal to or lower than 1.5. The forged crankshaft (1) can avoid an occurrence of machined surface cracks on the journals (J) and the crank pins (P) after the outer circumferential surface is machined.Type: ApplicationFiled: December 9, 2013Publication date: November 12, 2015Inventors: Hiroaki TAHIRA, Kisung KIM, Junichi OKUBO
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Publication number: 20140182414Abstract: There is provided an induction hardening steel excellent in quenching crack resistance. The induction hardening steel of the present embodiment includes, by mass percent, C: 0.35 to 0.6%, Si: at least 0.01% and less than 0.40%, Mn: 1.0 to 2.0%, S: more than 0.010% and at most 0.05%, Cr: 0.01 to 0.5%, Al: 0.001 to 0.05%, N: Ti/3.4 to 0.02%, and Ti: 0.005 to 0.05%, the balance being Fe and impurities, and satisfies the following formula (1): 2S-3Ti<0.040??(1) where, into each element symbol in formula (1), the content (mass %) of the corresponding element is substituted.Type: ApplicationFiled: July 4, 2012Publication date: July 3, 2014Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Kisung Kim, Hiroaki Tahira, Kaori Kawano, Koji Watari
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Publication number: 20130156630Abstract: There is provided a steel for induction hardening in which cracks are less liable to occur and high hardness and seizure resistance are attained even if a tempering process after induction hardening is omitted. The steel for induction hardening according to the present invention contains, by mass percent, C: 0.20 to 0.34%, Si: at most 0.20%, Mn: 0.75 to 2.0%, P: at most 0.03%, S: at most 0.20%, Cr: 0.05 to 1.2%, Ti: at least 0.002% and less than 0.030%, Al: 0.005 to 0.04%, and N: 0.0040 to 0.020%, the balance being Fe and impurities, and satisfies Formula (1): 1.20?Mn+Cr?2.10 ??(1) where the content (mass %) of each element is substituted for each of the symbols of elements in Formula (1).Type: ApplicationFiled: June 27, 2011Publication date: June 20, 2013Applicant: Nippon Steel & Sumitomo Metal CorporationInventors: Yuta Mizobe, Hiroaki Tahira, Kan Yoshino
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Publication number: 20130087014Abstract: To provide a forged crankshaft having an excellent wear resistance. The forged crankshaft according to the present embodiment includes a non-heat treated steel material. The non-heat treated steel material has a chemical composition which contains, by mass %, C: 0.45 to 0.70%, Si: 0.75 to 1.30%, Mn: 1.00 to 2.00%, S: 0.03 to 0.30%, Cr: 0.05 to 0.30%, Al: 0.005 to 0.050%, and N: 0.005 to 0.020%, the balance being Fe and impurities, and satisfies the following Formula (1): 1.1C+Mn+0.2Cr>2.0 ??(1) where a symbol of each element in Formula (1) is substituted by the content (mass %) of the each element. A matrix of the non-heat treated steel material is a ferrite-pearlite microstructure in which an area ratio of pro-eutectoid ferrite is less than 10% or a pearlite microstructure.Type: ApplicationFiled: June 13, 2011Publication date: April 11, 2013Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Kisung Kim, Hiroaki Tahira, Taketo Maejima
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Publication number: 20090304543Abstract: A steel for nitrocarburizing use, which comprises by mass percent, C: more than 0.45% to not more than 0.60%, Si<0.50%, Mn: more than 1.30% to not more than 1.70%, P?0.05%, S: 0.02 to 0.10%, Cr?0.30% and N: more than 0.007% to not more than 0.030%, and which further contains one or two elements selected from Al: more than 0.010% to not more than 0.10% and Ti: more than 0.005% to not more than 0.035%, with Al+Ti being 0.015% or more, with the balance being Fe and impurities, wherein V among the impurities is not more than 0.010%, and further satisfies the following 2 formulas, has high fatigue strength and excellent straightenability after the nitrocarburizing treatment, without performing the expensive heat treatment of quenching and tempering. Consequently, they are suitable as raw materials for nitrocarburized components: fn1=1.25C+Mn?0.1Cr, fn2=N?0.45Al?( 1/22)Ti.Type: ApplicationFiled: June 5, 2009Publication date: December 10, 2009Inventors: Makoto EGASHIRA, Hiroaki TAHIRA
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Patent number: 6838048Abstract: A steel for machine structural use which comprises, on the percent by mass basis, C: 0.1 to 0.6%, Si: 0.01 to 2.0%, Mn: 0.2 to 2.0%, S: 0.005 to 0.20%, P: not more than 0.1%, Ca: 0.0001 to 0.01%, N: 0.001 to 0.02% and Al: not more than 0.1%, with the balance being Fe and impurities, with a value of [Ca]e defined by [Ca]e=T.[Ca]?(T.[O]/(O)ox)×(Ca)ox of not more than 5 ppm or with a proportion of MnO contained in oxide inclusions of not more than 0.05 and a value of Ca/O of not more than 0.8 is excellent in machinability and, therefore, it can be used as a steel stock for various machine structural steel parts, such as in industrial machinery, construction machinery and conveying machinery such as automobiles. It is substantially free of Pb, hence suited for use as a steel friendly to the global environment. [Ca]e is the effective Ca concentration index (ppm by mass), T.[Ca] and T.Type: GrantFiled: September 30, 2002Date of Patent: January 4, 2005Assignee: Sumitomo Metal Industries, Ltd.Inventors: Takayuki Nishi, Hitoshi Matsumoto, Toru Kato, Koji Watari, Naoki Matsui, Hiroaki Tahira
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Patent number: 6797231Abstract: The invention provides a steel for machine structural use, which is excellent in machinability, comprising, in percent by mass, C: 0.1-0.6%. Si: 0.01-2.0%, Mn: 0.2-2.0%, S: 0.005-0.2%, Al: not more than 0.009%, Ti: not less than 0.001% but less than 0.04%, Ca: 0.0001-0.01%, O (oxygen): 0.0010-0.01%, and N: not more than 0.02% and satisfying the following relations (1) to (3): n0/S (%)≧2500 (1) n1/n0≦0.1 (2) n2≧10 (3) where n0: total number of sulfide inclusions not smaller than 1 &mgr;m per mm2 of a cross section parallel to the direction of rolling (number/mm2); n1: number of MnS inclusions having not smaller than 1 &mgr;m and containing not less than 1.Type: GrantFiled: November 15, 2002Date of Patent: September 28, 2004Assignee: Sumitomo Metal Industries, Ltd.Inventors: Naoki Matsui, Koji Watari, Takayuki Nishi, Toru Kato, Hitoshi Matsumoto, Hiroaki Tahira
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Publication number: 20030138343Abstract: The invention provides a steel for machine structural use, which is excellent in machinability, comprising, in percent by mass, C: 0.1-0.6%, Si: 0.01-2.0%, Mn: 0.2-2.0%, S: 0.005-0.2%, Al: not more than 0.009%, Ti: not less than 0.001% but less than 0.04%, Ca: 0.0001-0.01%, O (oxygen): 0.001-0.01%, and N: not more than 0.Type: ApplicationFiled: November 15, 2002Publication date: July 24, 2003Inventors: Naoki Matsui, Koji Watari, Takayuki Nishi, Toru Kato, Hitoshi Matsumoto, Hiroaki Tahira
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Publication number: 20030084965Abstract: A steel for machine structural use which comprises, on the percent by mass basis, C: 0.1 to 0.6%, Si: 0.01 to 2.0%, Mn: 0.2 to 2.0%, S: 0.005 to 0.20%, P: not more than 0.1%, Ca: 0.0001 to 0.01%, N: 0.001 to 0.02% and Al: not more than 0.1%, with the balance being Fe and impurities, with a value of [Ca]e defined by [Ca]e=T.[Ca]−(T.[O]/(O)ox)×(Ca)ox of not more than 5 ppm or with a proportion of MnO contained in oxide inclusions of not more than 0.05 and a value of Ca/O of not more than 0.8 is excellent in machinability and, therefore, it can be used as a steel stock for various machine structural steel parts, such as in industrial machinery, construction machinery and conveying machinery such as automobiles. It is substantially free of Pb, hence suited for use as a steel friendly to the global environment. [Ca]e is the effective Ca concentration index (ppm by mass), T.[Ca] and T.Type: ApplicationFiled: September 30, 2002Publication date: May 8, 2003Applicant: SUMITOMO METAL INDUSTRIES, LTD.Inventors: Takayuki Nishi, Hitoshi Matsumoto, Toru Kato, Koji Watari, Naoki Matsui, Hiroaki Tahira