Hammer Peening Treatment: Fatigue Strength Improvement and Repair of Welded Structures

Author:  C. Peyrac, F. Lefebvre, G. Elbel, C. Revilla-Gomez, K. Tabalaev, C. Verdu, J. Y. Buffière
Source:  ICSP-13
Doc ID:  2017121
Year of Publication:  2017
Abstract:  
Abstract: The main objective of this paper is to reveal and identify the parameters (residual stresses,geometry, strain hardening, etc.) which have an effect during the hammer peening operation and to understand the phenomena involved during fatigue stressing. Fatigue resistance of high-frequency mechanical impact treatment is investigated. Cyclic fourpoint bending tests are performed on high-strength welded steel S690 welded samples and hammer peened samples with different conditions of treatment with or without stress-relieving heat treatment. Microstructural characterisations with EBSD (electron backscattering diffraction) observations and residual stress analyses are presented. The main conclusions of this paper showed that hammer peening treatment improves the fatigue performance of welded joints. The residual compressive stresses are prominent. The microstructure does not seem to have any effect, despite the nanostructured layer. The geometry is of secondary importance. This point is confirmed by comparing with shot peening. Hammer peening treatment is also presented as repair technic.