Laser Peening vs. Shot Peening: engineering of residual stresses, surface roughness and cold working

Author:  0. Higounenc
Source:  Conf Proc 2014: ICSP-12 Goslar, Germany (pgs.226-231)
Doc ID:  2014080
Year of Publication:  2014
Abstract:  
In Laser Peening (LP), compared to Shot Peening (SP), the magnitude of residual compressive stress at the surface is the same: about 60% of elastic limit; but the depth is much higher. In Low Cycle Fatigue (LCF) depth of residual compressive stress is beneficial because it does not only delay crack initiation, but also crack propagation. Depth of residual stress is also critical in Foreign Object Damage (FOD) and Crack Grow Rate (CGR) applications. Changes in surface roughness, as soon as cold work, are much more significant in shot SP compared to LP. Those changes can have a positive, or a negative influence depending on application and condition: HCF or LCF, deteriorating or non-deteriorating environment such as corrosion or FOD, fretting, surface contact fatigue. Thus, LP is complementary to SP in some specific applications such as LCF, FOD, CGR. The other advantage is the extremely high process control that allow more easily to take into account the credit of LP in the design ..