Title:
MANUFACTURE OF HIGH STRENGTH STEEL PRODUCT FOR OIL WELL USE, EXCELLENT IN SULFIDE CRACKING RESISTANCE
Document Type and Number:
Japanese Patent JP3680628
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To manufacture the steel product with high energy efficiency by subjecting a steel stock which has a specific composition containing C, Si, Mn, P, S, Mo, Al, Ti, Nb, N, and B and in which yield strength and Mo content satisfy a specific relation to hot working, hardening treatment, and tempering under respectively specified conditions.
SOLUTION: The steel stock contains, by weight, 0.10-0.25% C, ≤0.5% Si, ≤0.5% Mn, ≤0.015% P, ≤0.005% S, 0.8-2.5% Mo, 0.005-0.1% Al, Ti in an amount in the range between 0.005 and 0.1%; and 3.4 times the content of N or more, 0.01-0.1% Nb, ≤0.01%; N, and 0.0005-0.0050% B, and further, a relation of Mo-0.15YS≥-18.8 (where YS is yield strength shown by ksi). The steel stock is heated to ≥1,150°C and hot worked. Finish working is completed at a temperature not lower than (Ar3 point +50°C). Quenching is done without delay to perform hardening, and a metallic structure in which as-hardened hardness in the position at the longest distance from the cooling surface becomes ≥95% of surface hardness is formed, followed by tempering at 660 to 720°C.
Inventors:
Shunji Sakamoto
Asahi Hitoshi
Asahi Hitoshi
Application Number:
JP12306799A
Publication Date:
August 10, 2005
Filing Date:
April 28, 1999
Export Citation:
Assignee:
SUMITOMO METAL INDUSTRIES,LTD.
International Classes:
B21B3/00; C21D8/10; C22C38/00; C22C38/14; C22C38/32; (IPC1-7): C21D8/10; B21B3/00
Domestic Patent References:
| JP5271772A | ||||
| JP7166293A | ||||
| JP10280037A |
Attorney, Agent or Firm:
Terutada Hogami
Mikiji Sugioka
Mikiji Sugioka