Title:
HIGH STRENGTH COLD ROLLED STEEL SHEET HAVING EXCELLENT YIELD STRENGTH, DUCTILITY, AND HOLE EXPANDABILITY, HOT DIP GALVANIZED STEEL SHEET, AND METHOD FOR PRODUCING SAME
Document Type and Number:
WIPO Patent Application WO/2018/110867
Kind Code:
A8
Abstract:
Provided are a high strength cold rolled steel sheet having excellent yield strength, ductility, and hole expandability, a hot dip galvanized steel sheet, and a method for producing same. The cold rolled steel sheet of the present invention comprises 0.06-0.2 wt% of carbon (C), 1.5-3.0 wt% of manganese (Mn), 0.3-2.5 wt% of silicon (Si), 0.01-0.2 wt% of aluminum (Al), 0.01-3.0 wt% of nickel (Ni), 0.2 wt% or less of molybdenum (Mo), 0.01-0.05 wt% of titanium (Ti), 0.02-0.05 wt% of antimony (Sb), 0.0005-0.003 wt% of boron (B), 0.01 wt% or less (but not 0%) of nitrogen (N), with the remainder comprising Fe and unavoidable impurities, and the microstructure thereof comprises, in terms of area fraction, 50% or more of bainite, 10% or more of tempered martensite (TM), 10% or less of fresh martensite (FM), 20% or less of residual austenite, and 5% or less of ferrite.
Inventors:
KWAK JAI-HYUN (KR)
CHO HANG-SIK (KR)
CHO HANG-SIK (KR)
Application Number:
PCT/KR2017/013762
Publication Date:
January 31, 2019
Filing Date:
November 29, 2017
Export Citation:
Assignee:
POSCO (KR)
International Classes:
C22C38/60; C21D8/02; C22C38/02; C22C38/06; C22C38/44; C22C38/50; C22C38/54; C22C38/58; C23C2/06
Attorney, Agent or Firm:
C&S PATENT AND LAW OFFICE (KR)
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