How Laser Peening Works, Step by Step
This step-by-step approach shows how the laser peening process
applies pressure to metallic structures, represented as the blocks of a grid.
The high energy laser beam hits the metal surface.
The red shading and arrows represent
the laser pulse arriving at the metal surface.
A plasma shock wave applies pressure
to the metal, reshaping its microstructure.
In isolation, we can see that the force of the shock wave has mechanically distorted and
expanded metal grain shapes. The grid they occupy looks wider and flatter.
Distorted metal pushes up against
surrounding metal structures.
If we look at the plastically deformed section as it continues to live on in the overall grid,
we can see that its larger shape pushes up against the parts of the metal not affected by laser peening.
Surrounding metallic structures adapt to the expanding metal.
The surrounding metal elastically adapts to the enlarged volume
of the metal affected by laser peening.
Healthy compressive residual stresses form.
The arrows show how compressive residual stress affects metal after laser peening.
The laser peened region in red has become larger, pushing outward.
The surrounding metal regions are trying to push inward to get back to their original shape.
The sum of these two opposing forces comprise compressive residual stress,
which helps prevent surface corrosion and cracking.
Deep compressive stresses extend
the useful life of components.
Laser peening produces measurable compressive residual stresses typically 1-2 mm deep below the metal surface.
In some cases laser peening penetrates up to 12 mm below the surface.
These deep compressive residual stresses counteract tensile stress
on parts operating at high speed or subject to other forces that lead to corrosion and cracking.