Title:
HIGH-STRENGTH STEEL SHEET AND METHOD FOR PRODUCING SAME
Document Type and Number:
WIPO Patent Application WO/2021/079756
Kind Code:
A1
Abstract:
A high-strength steel sheet that has a specific composition, while having a steel structure wherein: the area ratio of ferrite is from 30% to 80%; the area ratio of tempered martensite is from 3.0% to 35%; the area ratio of residual austenite is 8% or more; the value obtained by dividing the area ratio of residual austenite having an aspect ratio of 2.0 or more and a minor axis of 1 μm or less by the area ratio of all residual austenite is 0.3 or more; the value obtained by dividing the average Mn amount (mass%) in the above-described residual austenite by the average Mn amount (mass%) in ferrite is 1.5 or more; the value obtained by multiplying the value obtained by dividing the average Mn amount (mass%) in the above-described residual austenite by the average Mn amount (mass%) in ferrite by the average aspect ratio of residual austenite is 3.0 or more; the value obtained by dividing the average C amount (mass%) in the above-described residual austenite by the average C amount (mass%) in ferrite is 3.0 or more; and the value obtained by dividing the average C amount (mass%) in the above-described residual austenite by the average Mn amount (mass%) in the above-described residual austenite is less than 0.05. The amount of diffusible hydrogen in this high-strength steel sheet is 0.3 ppm by mass or less.
Inventors:
ENDOH KAZUKI (JP)
KAWASAKI YOSHIYASU (JP)
TOJI YUKI (JP)
KAWASAKI YOSHIYASU (JP)
TOJI YUKI (JP)
Application Number:
PCT/JP2020/038198
Publication Date:
April 29, 2021
Filing Date:
October 08, 2020
Export Citation:
Assignee:
JFE STEEL CORP (JP)
International Classes:
C21D9/46; C22C38/00; C22C38/06; C22C38/60
Domestic Patent References:
| WO2019188642A1 | 2019-10-03 | |||
| WO2019159771A1 | 2019-08-22 | |||
| WO2019188640A1 | 2019-10-03 | |||
| WO2016132680A1 | 2016-08-25 | |||
| WO2019111084A1 | 2019-06-13 |
Foreign References:
| JPS61157625A | 1986-07-17 | |||
| JP2003138345A | 2003-05-14 | |||
| JPS6123966B2 | 1986-06-09 |
Other References:
See also references of EP 4029957A4
Attorney, Agent or Firm:
KUMASAKA Akira et al. (JP)
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