Title:
STEEL MEMBER, HOT-ROLLED STEEL SHEET FOR SAID STEEL MEMBER AND PRODUCTION METHODS THEREFOR
Document Type and Number:
WIPO Patent Application WO/2018/186273
Kind Code:
A1
Abstract:
The purpose of the present invention is to provide a steel member with excellent fatigue resistance characteristics in the plastic strain range, a hot-rolled steel sheet as the material therefor and production methods therefor. A steel member, which contains 0.031-0.200 mass% Ti and in the structure of which at least 0.005 mass% of the Ti is precipitated as precipitates with a particle size of 20 nm or less. A hot-rolled steel sheet for said steel member that contains 0.031-0.200 mass% Ti and in the structure of which at least 0.005 mass% of the Ti is present as Ti solid solution. A production method for said steel member in which, after molding of the hot-rolled steel sheet, heat treatment is performed wherein the member is heated to a temperature greater than 550°C and not exceeding 1050°C and then cooled at an average cooling rate of at least 10°C/s for the temperature range of 550-400°C. A production method for said hot-rolled steel sheet in which a steel slab containing 0.031-0200 mass% Ti is extracted under temperature conditions higher than the equilibrium solid solution temperature TTi determined from a specified formula, after which finish-rolling is completed at a temperature of at least TTi-400°C, the sheet is cooled at an average cooling rate of at least 10°C/s for the temperature range from TTi-400°C to TTi-500°C, and is coiled at a temperature of TTi-500°C or less.
Inventors:
TOYODA SHUNSUKE (JP)
SUGIMOTO ICHIRO (JP)
KAWAMURA SHUJI (JP)
SUGIMOTO ICHIRO (JP)
KAWAMURA SHUJI (JP)
Application Number:
PCT/JP2018/013076
Publication Date:
October 11, 2018
Filing Date:
March 29, 2018
Export Citation:
Assignee:
JFE STEEL CORP (JP)
International Classes:
C22C38/00; B21B1/26; B21C37/08; C21D9/08; C21D9/46; C21D9/50; C22C38/14; C22C38/60
Foreign References:
| JP2009191360A | 2009-08-27 | |||
| JP2016204690A | 2016-12-08 | |||
| JP2017186634A | 2017-10-12 |
Attorney, Agent or Firm:
KUMASAKA Akira et al. (JP)
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