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Title:
HIGH STRENGTH STEEL MATERIAL HAVING EXCELLENT HYDROGEN-INDUCED CRACKING RESISTANCE AND LOW-TEMPERATURE IMPACT TOUGHNESS AND MANUFACTURING METHOD THEREFOR
Document Type and Number:
WIPO Patent Application WO/2019/107700
Kind Code:
A1
Abstract:
The present invention provides a high strength steel material having excellent hydrogen-induced cracking resistance and low-temperature impact toughness and a manufacturing method therefor, the steel material comprising, by weight %, 0.02-0.12% of C, 0.02-0.60% of Si, 0.6-1.6% of Mn, 0.020% or less of P (0% exclusive), 0.003% or less of S (0% exclusive), 0.002-0.060% of Sol.Al, 0.005-0.6% of Cu, 0.005-1.0% of Ni, 0.005-0.5% of Cr, 0.01-0.3% of Mo, 0.001-0.10% of Ti, 0.001-0.06% of Nb, 0.001-0.10% of V, 0.001-0.006% of N, 0.0002-0.0060% of Ca, and the balance of Fe and inevitable impurities, with (Ti+V+0.5Nb+0.5Mo) being 0.05% or more and (Ti+V+0.5Nb+0.5Mo)/C being 0.8 or greater, the steel material having a microstructure inclusive of ferrite; and at least one of pearlite, cementite, and MA (martensite-austenite complex phase) wherein the ferrite has a fraction of 90 % by area or more (100 % exclusive) and the at least one of ferrite, cementite, and MA (martensite-austenite complex phase) has a fraction of 10 % by area or less and wherein the ferrite structure includes 0.03 % by weight or more of fine carbonitride precipitates having an average size of 100 nm or less and is 20 μm or less in average grain size.

Inventors:
UM KYUNG-KEUN (KR)
KIM DAE-WOO (KR)
Application Number:
PCT/KR2018/008579
Publication Date:
June 06, 2019
Filing Date:
July 27, 2018
Export Citation:
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Assignee:
POSCO (KR)
International Classes:
C22C38/44; C21D8/02; C21D9/46; C22C38/46; C22C38/48; C22C38/50; C22C38/58
Foreign References:
KR20130131105A2013-12-03
KR20150124810A2015-11-06
KR20160075925A2016-06-30
KR20140118313A2014-10-08
JP2016006209A2016-01-14
Other References:
See also references of EP 3719162A4
Attorney, Agent or Firm:
C&S PATENT AND LAW OFFICE (KR)
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