Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
LOW YIELD RATIO HIGH-STRENGTH STEEL PLATE HAVING SUPERIOR STRAIN AGING RESISTANCE, PRODUCTION METHOD THEREFOR, AND HIGH-STRENGTH WELDED STEEL PIPE USING SAME
Document Type and Number:
WIPO Patent Application WO/2013/145771
Kind Code:
A1
Abstract:
The present invention provides a low yield ratio high-strength steel plate that is API 5L X70 grade or lower, a production method for said steel plate, and a high-strength welded steel pipe that employs the steel plate. The low yield ratio high-strength steel plate of the present invention is characterized in that: said steel plate has a predetermined component composition; the metal structure of the steel plate is a two-phase structure comprising bainite and island-shaped martensite; the island-shaped martensite has an area fraction of 3-15% and an equivalent circular diameter of 3.0 µm or less, and the remaining portion is bainite; the hardness variation in the plate thickness direction is ΔHV30 or less; the hardness variation in the plate width direction is ΔHV30 or less; the maximum hardness of the surface layer of the steel plate is HV230 or less; and in that the yield ratio is 85% or less and elongation is 22% or more according to a full thickness tensile test using a test fragment having a shape defined by the GOST standard.

Inventors:
SHIMAMURA JUNJI (JP)
NISHIMURA KIMIHIRO (JP)
Application Number:
PCT/JP2013/002158
Publication Date:
October 03, 2013
Filing Date:
March 29, 2013
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
JFE STEEL CORP (JP)
International Classes:
C22C38/14; B23K9/025; B23K9/23; C21D8/02; C21D9/08; C21D9/50; C22C38/58
Foreign References:
JP2011094230A2011-05-12
JP2009235524A2009-10-15
JP2012031509A2012-02-16
JP2010100903A2010-05-06
JP2012126925A2012-07-05
JPS5597425A1980-07-24
JPS5541927A1980-03-25
JPH01176027A1989-07-12
JPH066905B21994-01-26
JP2008248328A2008-10-16
JP2005060839A2005-03-10
JP2005060840A2005-03-10
Other References:
See also references of EP 2832890A4
Attorney, Agent or Firm:
KUMASAKA, Akira et al. (JP)
Akira Kumasaka (JP)
Download PDF:
View/Download PDF      PDF Help



 
Previous Patent: LOW YIELD RATIO HIGH-STRENGTH STEEL PLATE HAVING SUPERIOR STRAIN AGING RESISTANCE, PRODUCTION METHOD...

Next Patent: DISPLAY PAPER