Title:
PRODUCTION OF COLD ROLLED STEEL SHEET FOR PRESS FORMING, EXCELLENT IN FATIGUE CHARACTERISTICS
Document Type and Number:
Japanese Patent JP2699261
Kind Code:
B2
Abstract:
PURPOSE: To provide excellent fatigue characteristics and deep drawability by providing a three-layer extra-low carbon steel plate having surface layers enriched in boron.
CONSTITUTION: A steel constituting the inner layer has a composition consisting of ≤0.002% C, ≤0.20% Mn, ≤0.040% N, 0.02-0.07% Ti in the range satisfying Ti/(C+N)=5 to 20, ≤0.0003% B, and the balance Fe with inevitable impurities. A steel constituting the surface layer has a composition in which B content in the composition of the inner layer steel is enriched to 0.007-O.0020%. As to the thickness ratio at the time of constituting these steels into three layers, the ratio of the surface layer steel to the total thickness is regulated to 3-25% per one side. This three-layer steel is hot-rolled, pickled, and further cold-rolled at 75-90% draft. The resulting steel sheet is annealed at 750-850°C for ≤5min. Although the lamination method for the surface and the inner layer steel is not particularly limited, it is most industrial to form it into three layers by making the surface layers enriched in boron by a wire addition method at the time of continuous casting.
Inventors:
Toshinori Mizuguchi
Rie Abe
Makoto Yoshida
Rie Abe
Makoto Yoshida
Application Number:
JP16580194A
Publication Date:
January 19, 1998
Filing Date:
June 27, 1994
Export Citation:
Assignee:
Nippon Steel Corporation
International Classes:
C21D8/02; B32B15/01; C22C38/00; C22C38/14; (IPC1-7): C21D8/02; C22C38/00
Domestic Patent References:
| JP4185329A |
Attorney, Agent or Firm:
Masamitsu Akizawa (1 person outside)
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