Shot-peened induced residual stresses relaxation on steel DIN 34CrNiMo6 under different axial loading

Author:  N. Leguinagoicoa1, J. Albizuri1 1 Mechanical Dept., Faculty of Engineering of Bilbao, University of the Basque Country
Source:  ICSP14 Milan
Doc ID:  2022048
Year of Publication:  2022
Abstract:  
Shot-peening treatment (ISP: 8A & C:200%) was applied to improve the R: -1 axial fatigue strength of DIN 34CrNiMo6 (Q+T) steel specimens, due to the introduction of a compressive residual stress field in the near-surface area. However, this residual stress field tends to reduce or relax when an external stress, quasi-static or cyclic, is applied. Quasi-static tests were conducted to evaluate the role of tensile or compressive applied stress. Results showed that tensile applied stress induced lower relaxation and compressive applied stress required lower magnitude to initiate the stress relaxation. Cyclic tests, with R: -1, were developed to evaluate the influence of the cyclic applied stress magnitude on the surface stress relaxation. In addition, cyclic tests with load ratio R ≠ -1 (-0.5 < R < -0.25), including tensile mean stress, were performed to assess the influence of the tensile mean stresses on the residual stress relaxation. Results showed that, in the range of R studied, higher tensile mean stresses reduce the amplitude of residual stress relaxation.