公开(公告)号：US20180237874A1

公开(公告)日：2018-08-23

申请号：US15747583

申请日：2016-07-20

申请人： JFE STEEL CORPORATION

发明人： Kazuhiko YAMAZAKI ,  Shunsuke TOYODA ,  Noriaki MORIYASU ,  Kentaro IRISA

IPC分类号： C21D8/02 ,  C22C38/06 ,  C22C38/34 ,  C22C38/00 ,  C22C38/38 ,  C21D9/46 ,  C22C38/32 ,  C22C38/28

CPC分类号： C21D8/0226 ,  C21D8/0263 ,  C21D9/46 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/004 ,  C21D2211/005 ,  C21D2211/008 ,  C22C38/00 ,  C22C38/001 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/20 ,  C22C38/22 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/34 ,  C22C38/38 ,  C22C38/40 ,  C22C38/60

摘要： A high-strength hot-rolled steel sheet that has excellent punching workability and hole expandability, and a method for manufacturing the same. The hot-rolled steel sheet has a tensile strength of 980 MPa or more. The hot-rolled steel sheet has a chemical composition containing C, Si, Mn, P, S, Al, N, Ti, Cr, and B, and has a microstructure including a bainite phase having an area ratio of 85% or more as a main phase, and a martensite phase or martensite-austenite constituent having an area ratio of 15% or less as a second phase, the balance being a ferrite phase. The second phase has an average grain diameter of 3.0 μm or less, prior-austenite grains have an average aspect ratio of 1.3 or more and 5.0 or less, and recrystallized prior-austenite grains have an area ratio of 15% or less relative to non-recrystallized prior-austenite grains.

公开(公告)号：US20230120827A1

公开(公告)日：2023-04-20

申请号：US17905827

申请日：2021-03-11

申请人： JFE STEEL CORPORATION

发明人： Thihuyen DOAN ,  Sota GOTO ,  Hiroshi HASEGAWA ,  Noriaki MORIYASU ,  Takanori UMINO ,  Takeshi UEDA

IPC分类号： C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C21D8/02 ,  B21C47/02

摘要： Provided is a high strength steel sheet that has a tensile strength of 1180 MPa or more and a uniform elongation of 6 % or more. The high strength steel sheet has a chemical composition that contains predetermined components with a MSC of 3.0 mass% to 4.2 mass%. The high strength steel sheet has a microstructure including upper bainite in an area fraction of 70 % or more as a main phase, fresh martensite and retained austenite in a total area fraction of 7 % to 30 %, with the retained austenite having an area fraction of 2 % or more. The high strength steel sheet has a mechanical property with a uniform elongation of 6 % or more and a tensile strength of 1180 MPa or more.

公开(公告)号：US20210017636A1

公开(公告)日：2021-01-21

申请号：US16483500

申请日：2018-02-01

申请人： JFE STEEL CORPORATION

发明人： Taro KIZU ,  Noriaki MORIYASU ,  Shigeyuki NABESHIMA ,  Kazunori TAHARA ,  Kana SASAKI

IPC分类号： C23C2/06 ,  C22C38/12

摘要： There is provided a galvanized steel sheet more highly excellent in terms of punchability. The steel sheet has a specified chemical composition and a microstructure including a ferrite phase and a tempered bainite phase in a total amount of 95% or more in terms of area ratio, in which the average grain diameter of the microstructure is 5.0 μm or less, the amount of Fe precipitated is 0.10 mass % or more, the amount of Ti, Nb, and V precipitated in the form of precipitates having a grain diameter of less than 20 nm is 0.025 mass % or more in terms of precipitate C equivalent, and half or more of precipitates having a grain diameter of less than 20 nm are formed at random.