Relaxation Of Shot Peening Induced Compressive Stress During Fatigue Of Notched Steel Samples

Author:  Bergstrom, J. and Ericsson, T.
Source:  Conf Proc: ICSP-2, (p.241-248)
Doc ID:  1984057
Year of Publication:  1984
Abstract:  
This paper presents an experimental investigation of the surface residual stress relaxation behaviour of a shot peened 0.4% carbon low alloy steel under fatigue loading. A round specimen with a circumferential notch and a notch factor K sub t = 1.75 was fatigue loaded in both shot peened and ground conditions. Loading conditions included axial fatigue with stress ratio R = --1 and R = 0 and also R = --1 with an additional peak overload applied at 10 exp 6 cycles. Plain unnotched shot peened speciments were also fatigue loaded with stress ratio R = --1. The results show how the relaxation is dependent on load level, how the peak load changes the surface residual stress state, and that relaxation of the smooth and notched conditions is similar. Two different shot peening conditions were used, one with Almen intensity of 30-35 A (mm/100) and another of 50-55 A (mm/100). 8 ref. Descriptors: Chromium molybdenum steels-- Mechanical properties; Residual stress; Stress relaxation; Shot peening; Fatigue (materials; Notch sensitivity