scope:

This Standard details the requirements which are to be observed when the controlled working of metal surfaces is carried out in order to induce surface compressive stresses to improve the fatigue properties of parts under many types of service loading, and which also improve resistance to stress corrosion cracking in susceptible alloys, fretting corrosion and corrosion fatigue. For example they may be applied as a pretreatment to surface finishing Operations such as hard chromium plating to offset the loss of fatigue strength which would otherwise occur, or for the reversal of harmful surface tensile stresses perststing from earlier finishing operations such as grinding. These processes may also be used to improve the poor fatigue behaviour of decarburised surfaces.

The processes covered by this specification are:

Shot peening

Needle peening

Flail or Roto peening

Roller burnishing

Hammer peening

To align with Association Européenne des Constructeurs de Matériel Aérospatial (AECMA) specification EN 2409 mechanised shot peening employing cast steel shot or glass beads shall be the only techniques used for aerospace parts unless otherwise agreed by the design authority and to the satisfaction of the Quality Assurance Authority.

Processes which are not employed for the prime purpose of inducing a controlled uniform compressive surface stress, eg shot or grit blasting are outside the scope of this specification.

The application of the processes shall be limited to those materials on which test work has shown them to be beneficial within given intensity ranges