Cavitation shotless peening effects on fatigue crack growth behaviour under bending loads

Abstract

The effects of partial surface shotless peening on the fatigue crack growth behaviour of a ferritic steel have been experimentally investigated in this paper. Seven fatigue tests were performed on 4-point bend specimens fabricated from 700 Optim QL high strength steel. Three distinct extents of partial cavitation shotless peening, with respect to the crack tip and specimen symmetry line, were applied on the specimen geometry. Alternating Current Potential Difference (ACPD) was used to measure and monitor the crack depth during fatigue tests. The tests on partially surface peened specimens were conducted under two different load levels.The fatigue crack growth results from these experiments on partially peened specimens have been presented and compared with the results from an additional test on an unpeened specimen.The results show that the residual stress distribution fields formed due to the peening process play a significant role in the fatigue crack shape evolution, crack retardation and crack propagation behaviour of the material.