Title:
STEEL PRODUCT HAVING MARTENSITE STRUCTURE OF FINE FERRITE GRAIN BOUNDARY PRECIPITATION TYPE, AND METHOD FOR MANUFACTURING SAME
Document Type and Number:
WIPO Patent Application WO/2012/147439
Kind Code:
A1
Abstract:
The present invention addresses the problem of providing a steel product having a martensite structure of the fine ferrite grain boundary precipitation type as a structure having excellent heat treatment reliability, high toughness, and high strength and hardness, and of providing a method for manufacturing the same. The method for manufacturing a steel product having a martensite structure in which fine ferrite, cementite, or other carbide precipitates along grain boundaries so as to form a network comprises: heating steel stock or part of steel stock to or above a transformation point (A3) or (A1) by ohmic heat generated by the primary application of an electric current; allowing the steel to cool for 2 sec or less; reheating the steel by the secondary application of an electric current to raise or maintain the temperature at or above the temperature of the pearlite precipitation line on a continuous cooling diagram; and cooling the steel so as to pass over the pearlite precipitation line on a CCT diagram related to a continuous cooling transformation, and to pass through the martensite transformation point.
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Inventors:
NOZUE AKIRA (JP)
KIMPARA OSAMU (JP)
KIMPARA OSAMU (JP)
Application Number:
PCT/JP2012/058070
Publication Date:
November 01, 2012
Filing Date:
March 28, 2012
Export Citation:
Assignee:
OHASHI TECHNICA INC (JP)
NOZUE AKIRA (JP)
KIMPARA OSAMU (JP)
NOZUE AKIRA (JP)
KIMPARA OSAMU (JP)
International Classes:
C22C38/00; B23K20/00; B23P11/02; C21D9/00
Other References:
KAIZO MONMA ET AL., TEKKO ZAIRYOGAKU, 30 January 1976 (1976-01-30), pages 135 - 141
TAKESHI SHINODA ET AL.: "Appropriateness of Friction Hydro Pillar Processing (FHPP) conditions", PRE-PRINTS OF THE NATIONAL MEETING OF JWS, 2003, 73RD SERIES, 2003, pages 16 - 17
CUI LING ET AL.: "Effect of carbon content on mechanical properties of FSW carbon steel joints", PRE-PRINTS OF THE NATIONAL MEETING OF JWS, 2006, 78TH SERIES, 2006, pages 58 - 59
TAKESHI SHINODA ET AL.: "Appropriateness of Friction Hydro Pillar Processing (FHPP) conditions", PRE-PRINTS OF THE NATIONAL MEETING OF JWS, 2003, 73RD SERIES, 2003, pages 16 - 17
CUI LING ET AL.: "Effect of carbon content on mechanical properties of FSW carbon steel joints", PRE-PRINTS OF THE NATIONAL MEETING OF JWS, 2006, 78TH SERIES, 2006, pages 58 - 59
Attorney, Agent or Firm:
DOBASHI AKIRA (JP)
Hiroshi Tsuchihashi (JP)
Hiroshi Tsuchihashi (JP)
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Claims: