Work-Hardening During Peening

摘要

Shot peening is normally applied in order to improve the fatigue properties of components. This improvement is due to two factors: (1) Work-hardening of the surface layer and (2) Compressive residual stress in the surface layer. This article is about work-hardening and fatigue improvement and is aimed at shot peeners rather than scientists. The key to understanding work-hardening is a crystal defect called a "dislocation." In the early 1900s, scientists were baffled as to why metals started to plastically deform at much smaller stresses than their predicted theoretical strength. About 1934, various scientists proposed that the puzzle could be explained if the metals contained "dislocations". Many metallurgists remained skeptical of this dislocation theory until the development of the transmission electron microscope in the late 1950s.