Title:
高強度冷延鋼板及びその製造方法
Document Type and Number:
Japanese Patent JP6791371
Kind Code:
B2
Abstract:
Provided are a high-strength cold rolled steel sheet that has a tensile strength of 980 MPa or more, excellent ductility, and a low failure rate in a hole expanding test, and a method for manufacturing the same. A high-strength cold rolled steel sheet comprises a predetermined composition, wherein a total area ratio of ferrite and bainitic ferrite is 20 % or more and 80 % or less, an area ratio of retained austenite is more than 10 % and 40 % or less, an area ratio of tempered martensite is more than 0 % and 50 % or less, a ratio of retained austenite with an aspect ratio of 0.5 or less to the retained austenite is 75 % or more in area ratio, a ratio of retained austenite with an aspect ratio of 0.5 or less existing in ferrite grain boundaries with an orientation difference of 40° or more to the retained austenite with an aspect ratio of 0.5 or less is 50 % or more in area ratio, and an average KAM value of bcc phase is 1° or less.
Inventors:
Takaaki Tanaka
Yuki Taji
Yuki Taji
Application Number:
JP2019512698A
Publication Date:
November 25, 2020
Filing Date:
December 13, 2018
Export Citation:
Assignee:
jfe Steel Corporation
International Classes:
C22C38/00; C21D9/46; C22C38/06; C22C38/60; C23C2/28; C25D5/50
Domestic Patent References:
| JP2013237917A | ||||
| JP2018178247A |
Foreign References:
| WO2016021193A1 | ||||
| WO2016021197A1 | ||||
| WO2016113789A1 | ||||
| WO2016132680A1 |
Attorney, Agent or Firm:
Kenji Sugimura
Mitsutsugu Sugimura
Keisuke Kawahara
Nobuyuki Ichieda
Mitsutsugu Sugimura
Keisuke Kawahara
Nobuyuki Ichieda