Shot peening is a controlled process used to increase the fatigue life of components and fabrications.Shot peening is the process of impacting materials with spherical media to impart energy to the surface of a component. The amount of stress imparted to the material is proportional to the amount of energy applied; this energy introduces a surface and sub-surface compressive layer. The introduction of this compressive layer reduces the effect that any applied tensile stresses may have on the material.
Theoretically the greater the compressive stress achieved the greater the increase in component performance, but, there are many overriding factors which offset this advantage; not least is how compressive stress is imparted and the resultant effect on the material surface.
Each media type and media size has a limit as to how much energy it can impart, and although one can effectively ‘supercharge’ the media this is neither beneficial to the component nor the media. It is therefore important to understand the process limitations and how best to integrate the combined process tools to achieve the best results.
Controlled shot peening is regulated by a series of standards that control the media, the process and the proof of process.
They are as follows:
- Shot Peening Media SAE-AMS-2431.
- Automatic processing SAE-AMS-2430
- Computer controlled processing SAE-AMS-2432
- Almen Strips & Gauges SAE-J442
- Almen Strip usage SAE-J443