Improving the fatigue crack resistance of Waspaloy by shot peening

Four-point bending fatigue tests were conducted to study the effect of shot peening on the fatigue life of the nickel-base superalloy, Waspaloy. The influence of shot peening intensity on crack initiation, Stage I crack growth and the Stage I-to-Stage II crack growth transition phases, has been examined to identify the mechanisms by which shot peening improves fatigue resistance. The potential for extending the fatigue life of fatigue-damaged Waspaloy components has been explored by shot peening specimens which had been cyclic damaged to various degrees. The fatigue test was then continued after peening to ascertain the possibility of crack arrest or extending fatigue life. These experiments explore the possibility of 'healing' fatigue damage by a surface engineering treatment.