Title:
PRODUCTION OF HIGH STRENGTH GEAR
Document Type and Number:
Japanese Patent JP3480290
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To obtain a gear excellent in cold-workability, pitting resistance and wear resistance by executing graphitizing treatment of a steel containing specific contents of C and Si, successively, executing carburizing treatment and changing the structure in the region from the surface layer to a specific depth into cementite-graphite-martensite.
SOLUTION: The graphitizing treatment is applied to the steel containing, by wt.% 0.4-2.0% C, 0.5-1.0% Si and this structure is changed into ferrite- pearlite-graphite. After forming this steel material into the gear shape, carburize- hardening and tempering are applied, and the carbon concn. in the region from surface to at least 0.2 mm depth is quickly raised and the surface structure is changed to cementite-martensite-graphite. The carburizing treatment temp. is desirable to be higher than the first transformation point and lower temp. range than 310C+600°C. Wherein, C is carburizing gas concn. at the time of executing the carburizing treatment. Further, it is desirable that after the carburizing treatment, nitriding treatment is applied or the high-frequency induction heating is executed, and after holding at 800-900°C, the hardening is executed.
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Inventors:
Takuro Yamaguchi
Application Number:
JP210998A
Publication Date:
December 15, 2003
Filing Date:
January 08, 1998
Export Citation:
Assignee:
Nissan Motor Co., Ltd
International Classes:
C23C8/22; C21D9/32; C23C8/34; (IPC1-7): C21D9/32; C23C8/22; C23C8/34
Domestic Patent References:
| JP6323399A | ||||
| JP770646A |
Attorney, Agent or Firm:
Atsushi Nogami (5 outside)