Effect Of Shot Peening On Surface Fatigue Life Of Carburized And Hardened Aisi 9310 Spur Gears

Author:  Townsend, D.P. and Zaretsky, E.V.
Source:  NASA Tech. Paper #2047
Doc ID:  1982003
Year of Publication:  1982
Abstract:  
Gear surface fatigue endurance tests were conducted on two groups of ten gears each of carburized and hardened AISI 9310 spur gerars manufactured from the same heat of material. Both groups were manufactured with standard ground tooth surfaces. The second group was subjected to an additional shot-peening process on the gear tooth surfaces and root radius to produce a residual surface compressive stress. The gear pitch dia. was 8.89 cm. Test conditions were a gear temp. of 350 deg K, a max. Hertz stress of 1.71 x 10 exp 9 N/m exp 2 and a speed of 10 000 rev/min. The shot-peened gears exhibited pitting fatigue lives 1.6 times the life of standard gears without shot peening. Residual stress measurements and analysis indicate that the longer fatigue life is the result of the higher compressive stress produced by the shot peening. The life for the shot-peened gear was calculated to be 1.5 times that for the plain gear by using the measured residual stress difference for the standard and shot-peened gears. Descriptors: Gears-- Mechanical properties; Nickel chromium molybdenum steels-- Mechanical properties; Shot peening; Carburizing; Fatigue life; Wear resistance