PURPOSE: To obtain the high fatigue strength case hardening steel for gear capable of drastically increasing the effect of shot peening and satisfying high fatigue strength at low cost by limiting the chemical components in a steel as well as the size and number of inclusions therein.
CONSTITUTION: The above case hardening steel contains, by weight, 0.1 to 0.3% C, 0.05 to 0.5% Si, 0.4 to 1.5% Mn, 0.2 to 1.5% Cr, 0.015 to 0.05% Sol.Al., 0.0050 to 0.0200% Total N, ≤0.010% Total O and each ≤0.005% Ti, Nb and Z. Then, as an essential requirement, the number of oxide-series inclusions and nitride-series inclusions having ≥20μm diameter is regulated to ≤14 pieces per gram in the steel. Furthermore, if the above inclusions are incorporated by the number exceeding the above one, the bending strength of gear or the like is deteriorated.
TOYODA TAKESHI
MATSUMOTO KAZUAKI
SANPEI TETSUYA
NIPPON KOKAN KK
| JPS62274052A | 1987-11-28 | |||
| JPS62196322A | 1987-08-29 | |||
| JPS63137145A | 1988-06-09 |
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