Hi
Can anyone help me? I am new to shot peening and have a question regarding surface preparation after shot peening.
If a part has been shot peened and then requires light grit blasting for a surface preparation and a further coating process, will the grit blasting have any detrimental affect on the shot peened surface.

A mild grit blasting, if done properly, will enhance the shot peen properties by removing some of the damage caused by the surface dents. Honing or lapping the surface after peening is another similar practice which helps to remove the surface damage caused by the peening dents. The residual stress remains, that's good news. The opportunity to remove the damage of the dents,is also good news. Just don't grit blast so aggresively that you erode enough surface to relieve the compressive stresses.

Hi Jack
Thanks for the help , much appreciated.

I learn more knowledge from this .Thanks both of yours.

Grit blasting after shot peening is an unusual combination. The "damage caused by the surface dents" that Jack referred to is presumably the slight stress-raising effect of the rounded indentations. Where that is considered to be a problem the normal procedure is to double-peen using a much smaller size of shot after the first peening operation. Your requirement of a "light grit blasting" before a coating process implies that tiny notch-shaped indentations are needed to key in the coating material. Great care must be taken to ensure that the grit size used
is very small - otherwise you will introduce serious damage in the form of large stress-raising notch-shaped indentations.

You might want to learn what is taught by this US Patent
8,024,846
http://patft.uspto.gov/ and do quick search