I'm looking for some definitive proof one way or another that would prevent hard shot or CCW form being used in lieu of regular hardness media.

I'm not talking about what it says on the print or specification to use. I want to know if there is hard evidence that would convince me that hard shot should not be used on soft material i.e. aluminum. I am trying to convince an OEM that AWCH (AMS-2431/8) is the way to go across the board. I already know for a fact that AWCR will increase in hardness overtime with use. So I don't see why AWCH can not be used.

Old topic but still valid. Anyone have any insight?

Hard shot has less residual ductility than has softer shot. This means that there is a greater chance of particle fracture in use. Fracture would tend to occur more frequently when shot impacts hard items - such as test blocks - than when impacting soft aluminum alloy parts. Problems arise because fractured hard shot particles have enough kinetic energy to indent soft alloys severely - more severely than when impacting hard parts.

Thanks for the quick reply.

If the machine is properly equipped and maintained what difference if any would there be in the effectiveness of the peening process with regard to service life of the part?

My feeling is there would be no difference since the intensity and coverage is the same. I'm particularly interested in the effects on titanium.