Title:
STEEL FOR MACHINE STRUCTURAL USE AND ITS PRODUCTION
Document Type and Number:
Japanese Patent JP3221309
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To provide a steel for machine structural use, containing specific weight percentages of specific elements, free from delayed fracture for a fixed period, and having a tensile strength of specific value or above.
SOLUTION: This steel for machine structural use has a composition which consists of, by weight, 0.3-0.6% C, 0.5-2% Si, 0.1-1% Cu, 1.5-5% Cr, 0.05-1% Mo, 0.005-0.01% Al, 0.005-0.2% Nb, 0.05-0.5% Ni, 0.01-0.3% V, 0-0.5% Mn, ≤0.01% N, 0-0.15% Zr, 0-0.1% Ti, 0-0.005% B, and the balance Fe with inevitable impurities and simultaneously satisfies 0.4(%)≤Cu(%) +Mo(%) and 1.93≤Al(%)/[effective N(%)]=10, where equation [effective N(%)]=N(%)-Zr(%)/6.25-Ti(%)/3.43-B(%)/0.78 is satisfied, and in which the contents of P and S among the inevitable impurities are regulated to ≤0.015% and ≤0.01%, respectively. Further, this steel for machine structural use, excellent in delayed fracture resistance, can be produced by performing hardening and then tempering at a temp. less than the Ac1 point.
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Inventors:
Direct to Kuratomi
Takahiro Kushida
Takahiro Kushida
Application Number:
JP1498496A
Publication Date:
October 22, 2001
Filing Date:
January 31, 1996
Export Citation:
Assignee:
SUMITOMO METAL INDUSTRIES,LTD.
International Classes:
C21D9/00; C21D6/00; C22C38/00; C22C38/54; (IPC1-7): C22C38/00; C21D6/00; C22C38/54
Domestic Patent References:
| JP3243744A | ||||
| JP6306543A | ||||
| JP6228635A |
Attorney, Agent or Firm:
Morio Mori (1 outside)