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公开(公告)号：US20170197235A1
公开(公告)日：2017-07-13
申请号：US15324241
申请日：2015-07-13
发明人： Hiroshi SHUTO , Tatsuo YOKOI , Daisuke MAEDA , Eisaku SAKURADA , Takeshi TOYODA
IPC分类号： B21B1/22 , C23C2/28 , C23C2/40 , C22C38/16 , C22C38/14 , B32B15/18 , C22C38/06 , C22C38/04 , C22C38/02 , C22C38/00 , C21D9/46 , C21D8/02 , C23C2/06 , C22C38/12
CPC分类号： B21B1/22 , B21B1/26 , B21B3/00 , B21B2001/225 , B32B15/18 , C21D8/0226 , C21D8/0426 , C21D9/46 , C21D2211/002 , C22C38/001 , C22C38/002 , C22C38/005 , C22C38/02 , C22C38/04 , C22C38/06 , C22C38/12 , C22C38/14 , C22C38/16 , C23C2/06 , C23C2/28 , C23C2/40
摘要： A hot-rolled steel sheet according to the present invention has a chemical composition comprising, in mass %, C: 0.03 to 0.2%, Mn: 0.1 to 3.0%, P: 0.10% or less, S: 0.03% or less, Al+Si: 0.2 to 3.0%, N: more than 0% and equal to or less than 0.01%, O: more than 0% and equal to or less than 0.01%, and the balance: iron and impurities. A microstructure of the hot-rolled steel sheet contains bainite as the main constituent, and contains hard phases constituted by martensite and/or austenite in an amount of, in area fraction, equal to or more than 3% and less than 20% where 60% or more of the hard phase present in a sheet-thickness central portion have an aspect ratio of 3 or more, the hard phases present in the sheet-thickness central portion have a length in a rolling direction of less than 20 μm, and the sum of X-ray random intensity ratios of orientation and orientation as viewed from the rolling direction is 3.5 or more, and an X-ray random intensity ratio of orientation as viewed from the rolling direction is 1.0 or less.
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公开(公告)号：US20190177822A1
公开(公告)日：2019-06-13
申请号：US16325574
申请日：2016-08-18
IPC分类号： C22C38/28 , C22C38/22 , C22C38/16 , C22C38/14 , C22C38/12 , C22C38/08 , C22C38/06 , C22C38/04 , C22C38/02 , C22C38/00 , C21D9/46 , C21D8/02
摘要： A hot-rolled steel sheet includes, by mass %, C: 0.030% or more and less than 0.075%, Si+Al: 0.08% to 0.40%, Mn: 0.5% to 2.0%, and Ti: 0.020% to 0.150%, and includes a microstructure having a ferrite and a martensite. The hot-rolled steel sheet includes a microstructure having, by area %, 90% to 98% of the ferrite, 2% to 10% of the martensite. 0% to 3% of a bainite, and 0% to 3% of a pearlite. In the martensite, the number proportion of martensite grains having a hardness of 10.0 GPa or more is 10% or less, and a ratio N1/N2 of the number N1 of martensite grains having a hardness of 8.0 GPa or more and less than 10.0 GPa to the number N2 of martensite grains having a hardness of less than 8.0 GPa is 0.8 to 1.2.
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公开(公告)号：US20180023172A1
公开(公告)日：2018-01-25
申请号：US15546410
申请日：2016-03-28
发明人： Yoshinari ISHIDA , Riki OKAMOTO , Daisuke MAEDA
IPC分类号： C22C38/50 , C22C38/28 , C22C38/26 , C22C38/24 , C21D8/02 , C22C38/06 , C22C38/04 , C22C38/02 , C22C38/00 , C21D9/46 , C22C38/42 , C22C38/22
CPC分类号： C22C38/28 , B21B3/02 , B21C37/02 , C21D8/02 , C21D8/0205 , C21D8/0226 , C21D9/46 , C22C38/00 , C22C38/001 , C22C38/002 , C22C38/005 , C22C38/02 , C22C38/04 , C22C38/06 , C22C38/22 , C22C38/24 , C22C38/26 , C22C38/38 , C22C38/42 , C22C38/50 , C22C38/58
摘要： A steel sheet includes: a base iron; a scale of 10.0 μm or less in thickness on a surface of the base iron; a subscale between the base iron and the scale. In the subscale, an average value of Cr concentrations is 1.50 mass % to 5.00 mass %, and one part or more exist(s) where a ratio of Cr concentrations between two adjacent measurement regions separate by 1 μm is 0.90 or less or 1.11 or more in a range of 50 μm in length in a rolling direction. A percentage of an amount of Ti contained in carbide or carbonitride of 100 nm or more and 1 μm or less in grain diameter to a parameter Tieff represented by a formula “Tieff=[Ti]−48/14[N]” is 30% or less in which [Ti] denotes a Ti content (mass %) and [N] denotes a N content (mass %).
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公开(公告)号：US20150315683A1
公开(公告)日：2015-11-05
申请号：US14650086
申请日：2012-12-11
发明人： Daisuke MAEDA , Osamu KAWANO , Junji HAJI , Fuminori TASAKI
IPC分类号： C22C38/50 , C21D9/46 , C21D6/00 , C22C38/48 , C22C38/46 , C22C38/00 , C22C38/14 , C22C38/12 , C22C38/08 , C22C38/06 , C22C38/04 , C22C38/02 , C21D8/02 , C22C38/16
CPC分类号： C22C38/50 , C21D6/001 , C21D6/002 , C21D6/004 , C21D6/005 , C21D6/008 , C21D8/0226 , C21D8/0263 , C21D9/46 , C21D2211/005 , C21D2211/008 , C22C38/00 , C22C38/001 , C22C38/002 , C22C38/005 , C22C38/02 , C22C38/04 , C22C38/06 , C22C38/08 , C22C38/12 , C22C38/14 , C22C38/16 , C22C38/46 , C22C38/48 , C22C38/58
摘要： A hot-rolled steel sheet includes, as a chemical composition, by mass %, C: 0.030% to 0.10%, Mn: 0.5% to 2.5%, and Si+Al: 0.100% to 2.5%, in which the steel sheet has a microstructure including, by area fraction, ferrite: 80% or more, martensite: 3% to 15.0%, and pearlite: less than 3.0%, in which a number density of martensite having an equivalent circle diameter of 3 μm or more at a position which is at a depth of ¼ of the steel sheet thickness from the surface of the steel sheet, is 5.0 pieces/10000 μm2 or less, and the following Expression (I) is satisfied. R/DM2≧1.00 Expression (1) Here, R is an average martensite interval (μm) defined by the following Expression (2), and DM is a martensite average diameter (μm). R={12.5×(π/6VM)0.5−(⅔)0.5}×DM Expression (2) Here, VM is a martensite area fraction (%) and DM is the martensite average diameter (μm).
摘要翻译： 作为化学成分的热轧钢板以质量％计含有C：0.030％〜0.10％，Mn：0.5〜2.5％，Si + Al：0.100％〜2.5％ 通过面积分数的组织，包括：铁素体：80％以上，马氏体：3％〜15.0％，珠光体：小于3.0％，其中a相当的圆直径为3μm以上的马氏体的数密度 钢板表面厚度为1/4的位置为5.0个/10000μm2以下，满足下式（I）。 R / DM2≥1.00表达式（1）这里，R是由以下表达式（2）定义的平均马氏体间隔（μm），DM是马氏体平均直径（μm）。 R = {12.5×（＆pgr。/ 6VM）0.5-（⅔）0.5}×DM表达式（2）这里，VM是马氏体分数（％），DM是马氏体平均直径（μm）。
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公开(公告)号：US20170253944A1
公开(公告)日：2017-09-07
申请号：US15511302
申请日：2015-09-17
IPC分类号： C21D9/46 , C22C38/42 , C22C38/38 , C22C38/32 , C22C38/28 , C22C38/00 , C22C38/24 , C22C38/22 , C22C38/20 , C22C38/06 , C22C38/04 , C22C38/02 , C22C38/58 , C22C38/26
CPC分类号： C21D9/46 , C21D2211/001 , C21D2211/002 , C21D2211/005 , C21D2211/008 , C21D2211/009 , C22C38/00 , C22C38/001 , C22C38/002 , C22C38/005 , C22C38/02 , C22C38/04 , C22C38/06 , C22C38/20 , C22C38/22 , C22C38/24 , C22C38/26 , C22C38/28 , C22C38/32 , C22C38/38 , C22C38/42 , C22C38/58 , C22C38/60
摘要： A hot-rolled steel sheet including predetermined components, in which the amounts of Cr and Al added satisfy Expression (1) below, a metallographic structure has, by % by volume, a ferrite fraction of more than 90% and 98% or less, a martensite fraction of 2% to less than 10%, and, a fraction of a residual structure made of one or more of pearlite, bainite, and residual austenite being less than 1%, the ferrite has an average circle-equivalent diameter of 4 μm or more and a maximum circle-equivalent diameter of 30 μm or less, and the martensite has an average circle-equivalent diameter of 10 μm or less and a maximum circle-equivalent diameter of 20 μm or less. [Cr]×5+[Al]≧0.50 Expression (1) Here, in Expression (1), [Cr] represents an amount of Cr (mass %), and [Al] represents an amount of Al (mass %).
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公开(公告)号：US20170145538A1
公开(公告)日：2017-05-25
申请号：US15323617
申请日：2015-07-13
发明人： Hiroshi SHUTO , Tatsuo YOKOI , Daisuke MAEDA , Eisaku SAKURADA , Takeshi TOYODA
IPC分类号： C21D9/46 , C23C2/06 , C23C2/28 , C21D8/02 , C22C38/16 , C22C38/08 , C22C38/12 , C22C38/06 , C22C38/04 , C22C38/02 , C22C38/00 , B21B3/00 , C22C38/14
CPC分类号： C21D9/46 , B21B1/26 , B21B3/00 , B32B15/00 , B32B15/011 , B32B15/013 , B32B15/04 , B32B15/043 , B32B15/18 , C21D8/02 , C21D8/0205 , C21D8/0226 , C21D8/0247 , C21D2211/001 , C21D2211/008 , C22C38/00 , C22C38/001 , C22C38/002 , C22C38/02 , C22C38/04 , C22C38/06 , C22C38/08 , C22C38/12 , C22C38/14 , C22C38/16 , C22C38/58 , C23C2/06 , C23C2/28 , C23C30/005 , Y10T428/12799 , Y10T428/12951 , Y10T428/12958 , Y10T428/12972
摘要： [Object] To provide a hot-rolled steel sheet having excellent fatigue characteristics and workability in the rolling direction.[Solution] A hot-rolled steel sheet according to the present invention has a chemical composition consisting of, in mass %, C: 0.03 to 0.2%, Mn: 0.1 to 3.0%, P: 0.10% or less, S: 0.03% or less, Al+Si: 0.2 to 3.0%, N: more than 0% and equal to or less than 0.01%, O: more than 0% and equal to or less than 0.01%, and the balance: iron and impurities. A microstructure of the hot-rolled steel sheet contains ferrite as the main constituent, and contains hard phases constituted by martensite and/or austenite in an amount of, in area fraction, equal to or more than 3% and less than 20%, hard phases with an aspect ratio of 3 or more account for 60% or more of the hard phases present in a sheet-thickness central portion, a length in a rolling direction of the hard phases present in the sheet-thickness central portion is less than 20 μm, an average aspect ratio of ferrite grains is less than 5, and the sum of X-ray random intensity ratios of orientation and orientation as viewed from the rolling direction is 3.5 or more, and an X-ray random intensity ratio of orientation as viewed from the rolling direction is 1.0 or less.
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