Long Life Fatigue Behavior of Shot Peened Steels

Abstract:

The fully reversed long life fatigue cycle behaviour of shot peened steels has been investigated. In the case of air cooled forged 0.4%C and 0.7%C steels, shot peening resulted in a relatively small effect on fatigue life (+2.2% and-2.0% respectively) owing to cyclic softening. Fatigue cracks in the shot peened specimens have been observed to initiate in sub-surface layers, reducing the detrimental effect of surface roughness. Neither cyclic softening nor hardening occurred in the smooth non shot peened samples cycled under the same conditions. Shot peening quench and tempered 0.5%C steel samples resulted in a reduced fatigue limit of 12.0% due to cyclic softening. Relaxation of the residual stresses occurred quickly in these steels due to adjustment and rebalancing of the residual stresses caused by the plastic strain. The effect of cyclic softening and shift in crack initiation site rather than the residual peening stresses was significant in determining the fatigue life of these shot peened steels.

• Periodical: Key Engineering Materials (Volume 627)
• Pages: 9-12
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.627.9
• Online since: September 2014
• Authors: Alan Plumtree
• Keywords: Fatigue Limit, Shot Peening, Steel Forging

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