Effect of material, heat treatment, grinding and shot peening on contact fatigue life of carburised steels

Contact fatigue resistance has been tested in a roller to roller rig. The test simulates the conditions in a gearbox with finite slip and with impurities in the lubricant. Two case hardened alloys were included in the study, different sequences of carburising and grinding and finally additional shot peening. The tested samples were characterised with respect to residual stress, microstructure, hardness and surface roughness. The contact fatigue tests show significant scatter in the amount of damage. The shot peened samples gave the least amount of contact fatigue damage. A slight difference in the amount of damage could be seen when comparing the ground and hardened and hardened and ground samples. No difference in the amount of damage could be seen between the two carburised steels. (C) 1999 Elsevier Science Ltd. All rights reserved.