MODUK DEF STAN 03-021 PDF

This Defence Standard (Def Stan) details the requirements to be observed when the controlled mechanical working of metal surfaces is carried out in order to induce surface and sub-surface compressive stresses. This may be done in order to improve the fatigue properties of items under many types of service loading or to improve resistance to stress corrosion cracking in susceptible alloys, fretting corrosion and corrosion fatigue. For example, they may be applied as a pre-treatment to surface finishing operations, such as hard chromium plating or hard anodising, to offset the loss of fatigue strength which would otherwise occur, or for the reversal of harmful surface tensile stresses persisting from earlier finishing operations such as grinding. These processes may also be used to improve the poor fatigue behaviour of decarburized surfaces or improve the fatigue performance in the toe region of welded joints.

This standard also includes guidance for the control of coverage during manual peening operations.

The processes covered by this specification are:

a) Shot peening;

b) Needle peening;

c) Rotary flap peening;

d) Hammer peening;

e) Roller burnishing;

f) Laser peening.

Processes which are not employed for the prime purpose of inducing a controlled uniform compressive surface stress, e.g. abrasive 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.

The process known as autofrettage is not covered by this Def Stan.