5Sumie S, Nobuhiko I. The Past and Future of High-Strength Steel for Valve Springs [J]. Kobelco Technology Review, 2005,26(11) : 21.
6Nam W J, Choi H C. High Strength Steel Wire Rod for Suspension Coil Spring [J]. Wire Journal International, 1996, (5): 94.
7Kawakami H, Yamada Y, Ashida S, et al. Effect of Chemical Composition on Sag Resistance of Suspension Spring [J]. SAE Technical Paper Series, 1983, (1) : 28.
8Borik F, Bisa V A, Smith Y. Sag Resistance of Si-Mo and Si- Cr Spring Steel [J]. SAE Technical Paper Series, 1979, (1) : 409.
9Yamamoto T. Spring Steel Having a Good Sag Resistance and a Good Hardenability [P]. U.S. Patent: 544406,1985.
10Yamada Y. Spring Steel for Vehicles [P]. U.S. Patent: 4409026,1983.
