The Effect of Shot Peening Coverage on Residual Stress, Cold Work and Fatigue in a Nickel-Base Superalloy

Author:  J. Cammett, P. Prev
Source:  Conf Proc: ICSP-9 (pg 429-435)
Doc ID:  2005120
Year of Publication:  2005
Abstract:  
ABSTRACT The goal of this work was to determine effects of shot peening (SP) coverage on the compressive residual stress magnitude, depth, and relaxation of residual stresses due to thermal exposure, as well as fatigue strength of IN718, a nickel-base superalloy. The residual stress-depth profiles (both depth of compression and magnitude) for coupons shot peened to different coverage levels of 82% (0.2T where T = time to achieve full area coverage) to 400% (4T) show a slight trend of increased depth of compression with increase in coverage. Though having similar residual stress distributions, the coupons exhibited markedly different cold work distributions. While 82% (0.2T) coverage resulted in less than five percent cold work, increasing coverage to 400% (4T) resulted in cold work as high as thirty-five percent. The heavily cold worked surfaces of the higher coverage coupons exhibited significant relaxation of surface residual stresses, accompanied by corresponding reduction of cold work upon thermal exposure at 525