Development of High Strength Transmission Gear Steels

• Published in: DENKI-SEIKO Vol. 65; no. 1; pp. 13 - 21
• Main Authors: Mizuno, Kohki, Matsubara, Toshihiko, Amano, Masaki, Hatano, Atsumi, Nakamura, Sadayuki
• Format: Journal Article
• Language: Japanese; Chinese
• Published: Daido Steel Co., Ltd 01.01.1994
• ISSN: 0011-8389; 1883-4558
• DOI: 10.4262/denkiseiko.65.13

In order to minimize the size of transmission gears in passenger cars, high performance gear steels have been demanded. This study has been conducted, under this back-ground, to design the high toughness and high fatigue strength steel. The results obtained from this study are as follows. 1) The chemical composition of the new gear steel is 0.2C-0.05Si-0.4Mn-0.5Ni-0.6Cr-0.8Mo-Nb. This steel is characterized by decreasing silicon content to eliminate grain boundary oxidation and by increasing nickel and molybdenum content to enhance the case toughness. 2) The new steel shows 1.2 times higher fatigue strength and 2 times larger impact load than conventional steel such as JIS SCM 420. 3) The application study appears that the new steel has reduced the module of the transmission gear and gear teeth width by 20%.