Shaping the Future - Laser Peening Technology Has Come of Age

Author:  Lloyd A. Hackel, Metal Improvement Company
Source:  The Shot Peener magazine, Vol 19 / Issue 3, Summer 2005
Doc ID:  2005028
Year of Publication:  2005
Abstract:  
Introduction It is well known that placing residual compressive stress into the surface of metals provides performance benefits including increased fatigue lifetime, increased fatigue strength, resistance to stress corrosion cracking and resistance to general corrosion. For many years, shot peening has been the mainstay of surface treatment, providing a level of compressive residual stress (CRS) in the skin that is a large fraction of the yield strength of the material and typically extending 10 mils into the surface. This CRS, although shallow, significantly resists crack initiation and gives excellent resistance to stress related corrosion failures. However, in many situations, the depth of residual stress provided by shot peening is too shallow. Cracks can grow past the peened depth or flaws in the material or damage created in use, such as scratches or corrosion, create initiation sites that penetrate beyond the protective layer of compressive stress. In many applications a deeper level of compressive stress is needed.