Shot Peen Impact on Life, Part 2: Single Particle Impact Tests Using Production Shot

Author:  M Tufft
Source:  Conf Proc: ICSP-7 (pg 254-263)
Doc ID:  1999036
Year of Publication:  1999
Abstract:  
Shot peening, long recognized for its potential to increase life capability, can also cause the reverse effect. Peening intensity, independent of shot size or incidence angle, typically correlates with residual stress profile depth observed. However, results from a designed experiment indicate that residual stress or intensity is not the only critical factor controlling low cycle fatigue life behavior. Shot size, coverage, incidence angle and velocity or strain rate also appear to be significant. Single particle impact tests using production shot were conducted to gain insight into the physical mechanisms and material changes corresponding to the shot peening conditions resulting in reduced life capability. Development of microstructure and dimple profiles was studied over a range of shot velocities and incidence angles. The results of this effort are presented here. This led to the development of a Fracture Mechanics/Threshold Behavior predictive model which is presented in Part 3. As a result, a dual criteria for damage was developed which includes a microstructural damage depth, and an impact severity criteria which is linked to the total shot velocity.