Title:
METHOD FOR SPHEROIDIZING ANNEALING CASE-HARDENING STEEL
Document Type and Number:
WIPO Patent Application WO/2021/065713
Kind Code:
A1
Abstract:
Provided is a spheroidizing annealing method with which the time required for spheroidizing annealing can be shortened by eliminating a gradual cooling step, and a structure in which carbides are uniformly dispersed can be obtained. This method comprises annealing a steel material that has an A1 point temperature of 750ºC or higher and contains, in terms of mass%, 0.15-0.26% of C, 0.05-1.00% of Si, 0.1-0.9% of Mn, 0.030% or less of P, 0.030% or less of S, 1.30-2.50% of Cr, 0.020-0.050% of Al, 0.0040-0.0300% of N, at least one of 0-2.00% of Ni and 0-2.00% of Mo as desired, and at least one of 0-0.10% of Nb, 0-0.200% of Ti, 0-0.0050% of B and 0-0.500% of V as desired, with the remainder consisting of Fe and unavoidable impurities, such that the spheroidizing annealing holding temperature T (ºC) satisfies the condition (A1 point-30)≤T≤(A1 point-5) and the spheroidizing annealing holding time t (h) satisfies the condition t≥120/(T-A1+50).
Inventors:
MATSUO KENTA (JP)
HASHIMOTO KAZUYA (JP)
HASHIMOTO KAZUYA (JP)
Application Number:
PCT/JP2020/036247
Publication Date:
April 08, 2021
Filing Date:
September 25, 2020
Export Citation:
Assignee:
SANYO SPECIAL STEEL CO LTD (JP)
International Classes:
C21D6/00; C21D1/32; C22C38/00; C22C38/18; C22C38/54
Foreign References:
| JP2012072427A | 2012-04-12 | |||
| JP2014185389A | 2014-10-02 | |||
| JP2012126953A | 2012-07-05 | |||
| JP2016098384A | 2016-05-30 |
Attorney, Agent or Firm:
TAKAMURA Masaharu et al. (JP)
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