The amount of material that can be removed without affecting fatigue life depends primarily on the depth of the compressed layer. This depth is rarely measured, whereas the peening intensity - which is directly related to that depth - is readily available. AMS2432 makes a brave attempt to offer guidance. Harder materials have a shallower compressed depth than have softer materials (3.6.2.1 cf 3.6.2.2)for a given peening intensity. Hence only 5% (of relevant minimum peening intensity) is allowed for hard over 1517 MPa U.T.S.) materials and 10% for softer materials. The "relevant minimum peening intensity arc height" depends on the strip type. AMS2432 is clear that the recommended height is based on the use of A strips. If N strips are being used then the allowable removal is either 5%/3 or 10%/3 - depending on the U.T.S. of the component. If C strips are being used then the allowable removal is either 5% times 3.5 or 10% times 3.5 - again depending on the U.T.S. of the component material. In all cases the percentage removal is to be based on the minimum of the customer's allowable intensity range.
