Shot peening is characterized by three phenomena :
- a compression of the part’s outer surface
- a phenomenon of outer surface hardening
- a degradation of the surface condition
Setting into compression is a result of the extension of the surface material grain and a natural response of the material to fill the void generated by media’s impact.
According there phenomena and to the following principles of mechanical physics :
- A part ALWAYS breaks in traction
- We can ADD two stress fields
The part being “artificially” into compression, when it is subjected to fatigue cycles (tension, compression), it is “alleviated” if it is in tension.
That’s why a blasted part has an increased lifetime (enhanced endurance phenomenon) since 90% of the parts breackages have their origin in its surface.