Title:
STEEL SHEET
Document Type and Number:
WIPO Patent Application WO/2022/070873
Kind Code:
A1
Abstract:
The purpose of the present invention is to provide a steel sheet having excellent toughness at heat affected portions where there is a large heat input during welding as much as 20.0 kJ/mm or more of welding heat input. This steel sheet has a compositional makeup including, in mass%, 0.030-0.120% of C, 0.01-0.15% of Si, 0.80-2.00% of Mn, not more than 0.020% of P, 0.0005-0.0050% of S, 0.005-0.100% of Al, 0.005-0.030% of Ti, 0.0030-0.0080% of N, 0.0005-0.0030% of Ca, and not more than 0.0040% of O, the remaining portion being Fe and unavoidable impurities. The contained amounts of S, Ca, and O satisfy formula (1). Among precipitates of TiN, the mass proportion of precipitates having an equivalent circle diameter exceeding 0.1 μm is 40% or more. (1): 0<(Ca-(0.18+130×Ca)×O)/1.25/S<1 (wherein the element symbols indicate the contained amounts of respective elements).
Inventors:
ARAO RYO (JP)
UEDA KEIJI (JP)
TOMOZAWA MASANARI (JP)
NAKASHIMA KOICHI (JP)
UEDA KEIJI (JP)
TOMOZAWA MASANARI (JP)
NAKASHIMA KOICHI (JP)
Application Number:
PCT/JP2021/033646
Publication Date:
April 07, 2022
Filing Date:
September 14, 2021
Export Citation:
Assignee:
JFE STEEL CORP (JP)
International Classes:
C22C38/00; C22C38/14; C22C38/58
Foreign References:
| JP2013060631A | 2013-04-04 | |||
| JP2010174314A | 2010-08-12 | |||
| JP2010111924A | 2010-05-20 | |||
| JP2014029019A | 2014-02-13 | |||
| JPH04143246A | 1992-05-18 | |||
| JPH05279789A | 1993-10-26 |
Attorney, Agent or Firm:
KUMASAKA Akira et al. (JP)
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