Fatigue improvement and residual stress relaxation of shot-peened alloy steel DIN 34CrNiMo6 under axial loading

Shot-peening treatment was applied to a quenched and tempered DIN 34CrNiMo6 steel improve its high-cycle R: −1 axial fatigue strength. Compared with the machined condition, increase in limit 21.8%. S-N curves for shot-peened as condition were presented compared those obtained previous research rotating bending fatigue, including mirror-polished specimens. The shot-peening this work (Isp: 8A 200% coverage) (Q + T) introduced compressive residual stress field an surface roughness, well minor variations microstructure, hardness FWHM (full width of diffraction peak at half maximum intensity) parameter. tended reduce when external is applied. This due onset plastic strain. In paper, two types quasi-static tests conducted by applying six different magnitudes directions (compressive or tensile). order assess their influence on relaxation stresses. Due stresses, if compressive, deformations achieved lower magnitude. addition, under cyclic evaluated four magnitudes. cyclic-softening behaviour Q T steel, mechanical properties must be considered strains. With experimental data, logarithmic model predict evolution stresses number cycles presented.