Laser peening technology has matured into a fully qualified production process that is now in routine and reliable use for a range of aerospace alloys. The technology is capable of extending the fatigue life and stress corrosion cracking life of components, and will enable designers to consider higher stress levels in life limited designs. Applications under development for steels include high and medium strength steels used in off shore oil exploration and production, titanium, aluminum and even ceramics and plastics as well as life extension of steel and aluminum welds. Fixed systems to treat components and transportable systems capable of field operations are available with a moveable beam that allows peening directly as needed on large structures.
In many applications in the petrochemical industry, steel components and pressure vessels are required to carry high tensile stress loads, reside in corrosive environments and very often are subjected to cyclic loading. The tensile component of stress in general drives fatigue or corrosion failure. Treatments such as shot peening and surface rolling have been used to apply compressive stress to a thin surface layer to retard crack formation and growth and consequently to mitigate failures. These processes are good but somewhat limited in the improvement achieved due to the limited depth of compressive stress achieved and due to the significant level of cold work created in the compression zone. Laser peening, a production technology new to many engineers, creates compressive stress five times or more deeper and in a very controlled fashion and with very little cold work. It is relatively well known that cold-worked regions contain a higher concentration of dislocation energy and consequently are anodic to non-cold-worked regions. Putting in compressive stress with little cold-work results in significantly reduced susceptibility to corrosion and corrosion cracking.
