Turbine discs in steam turbines are stressed by differing loads. In the corrosive environment stress crack corrosion is particularly problematic. "Stress corrosion" is a process in which corrosion and stretching of a metal as a result of internal or applied tensile stresses are involved. Stress crack corrosion is crack formation as a result of stress corrosion. (DIN EN ISO 8044:1999). Deep residual compressive stresses are particularly significant here, in preventing stress crack corrosion. By deep rolling, one can achieve residual compressive stresses up to several millimeters deep and consequently create proportionate resistance to external tensile stresses.
Deep rolling a turbine blade