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Title:
METHOD FOR MANUFACTURING STEEL COMPONENT HAVING LOCALLY SOFTENED SECTION
Document Type and Number:
WIPO Patent Application WO/2021/181866
Kind Code:
A1
Abstract:
Provided is a method for manufacturing a steel component, the method including: a step for preparing a steel plate having a chemical composition in which 0.05-0.40 mass% of C, 0-2.0 mass% of Si, 1.0-3.0 mass% of Mn, 0.010-1.0 mass% of Al, greater than 0 and equal to or less than 0.100 mass% of P, greater than 0 and equal to or less than 0.010 mass% of S, greater than 0 and equal to or less than 0.010 mass% of N, and 0.0005-0.010 mass% of B are contained and the remainder consists of iron and inevitable impurities; a step for heating the steel plate to a temperature that is equal to or greater than the Ac1 point (ºC) and less than the Ac3 point (ºC)+10ºC; a processing step for, after the heating step, applying a distortion that is equal to or greater than 0.5% at a temperature that is equal to or greater than 675ºC and less than the Ac3 point+10ºC; a step for, after the processing step, holding or slow cooling the steel plate for 1 to 120 s at an average cooling speed of 0 to 15ºC/s; and a step for, after the holding/slow cooling step, cooling to the Ms point (ºC)-50ºC, wherein the average cooling speed from the temperature in the heating step to the Ms point (ºC)-50ºC is controlled to be equal to or greater than 10ºC/s.

Inventors:
MIZUTA NAOKI
Application Number:
PCT/JP2021/001266
Publication Date:
September 16, 2021
Filing Date:
January 15, 2021
Export Citation:
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Assignee:
KOBE STEEL LTD (JP)
International Classes:
B21D22/20; B21D22/26; B21J1/02; B21J5/00; C21D1/18; C21D8/00; C22C38/00; C22C38/06; C22C38/38; C22C38/58
Domestic Patent References:
WO2014034714A12014-03-06
Foreign References:
JP3462922B22003-11-05
JP2015175051A2015-10-05
JPH11193439A1999-07-21
JP2017078189A2017-04-27
JP2011179028A2011-09-15
JP2020042274A2020-03-19
JP2020172764A2020-10-22
Other References:
See also references of EP 4116003A4
Attorney, Agent or Firm:
YAMAO, Norihito (JP)
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