utspg1980
New member
- Apr 17, 2009
- 7
My apologies if this is the "wrong" forum. It seems like this could fall into a few different categories.
I'm curious what you guys think of using thermography to replace search peening for corrosion investigation in decently thick aluminum parts.
For years we've used "search peening" to look for corrosion on certain locations on aircraft. For example, wing skins. This is performed repeatedly over periodic maintenence cycles.
This is per tech. docs. and in our case, "search peening" would essentially be defined as shot peening at a lower intensity than would normally be used to enduce a full residual compressive zone on a part. The idea is that although it does not leave the full residual compressive zone, it compresses the material sufficiently to cause corrosion to delaminate and "explode" into view.
Our OEM (Boeing) has removed this process from the tech docs, and we don't know why. I speculate that it is from concern that over time (and multiple processes) the material could become "over peened", leaving stress risers in the material and inducing cracks.
I talked to our NDT group (who admits that they are newbies when it comes to thermography), and they aren't sure that thermography would be a good inspection for this area. Material thicknesses range from .120-.360. 7xxx series aluminum.
I personally am more familiar with thermography use on composites.
NDT thinks this alum is too thick for thermo. They said it is typically used on thinner metals, such as .050 thick.
My thinking is this: the search peening process doesn't "inspect" the entire thickness. Only the upper surface.
Would using thermography on a metal that is "too thick" at least allow an inspection of the upper surface of that metal? Or does it just completely invalidate the results? My NDT group did not know the answer to this.
If thermo will allow us to inspect the upper .050" of the material, I think this would be a good substitute for search peening.
Thoughts? Alternative suggestions?
Thanks you.
I'm curious what you guys think of using thermography to replace search peening for corrosion investigation in decently thick aluminum parts.
For years we've used "search peening" to look for corrosion on certain locations on aircraft. For example, wing skins. This is performed repeatedly over periodic maintenence cycles.
This is per tech. docs. and in our case, "search peening" would essentially be defined as shot peening at a lower intensity than would normally be used to enduce a full residual compressive zone on a part. The idea is that although it does not leave the full residual compressive zone, it compresses the material sufficiently to cause corrosion to delaminate and "explode" into view.
Our OEM (Boeing) has removed this process from the tech docs, and we don't know why. I speculate that it is from concern that over time (and multiple processes) the material could become "over peened", leaving stress risers in the material and inducing cracks.
I talked to our NDT group (who admits that they are newbies when it comes to thermography), and they aren't sure that thermography would be a good inspection for this area. Material thicknesses range from .120-.360. 7xxx series aluminum.
I personally am more familiar with thermography use on composites.
NDT thinks this alum is too thick for thermo. They said it is typically used on thinner metals, such as .050 thick.
My thinking is this: the search peening process doesn't "inspect" the entire thickness. Only the upper surface.
Would using thermography on a metal that is "too thick" at least allow an inspection of the upper surface of that metal? Or does it just completely invalidate the results? My NDT group did not know the answer to this.
If thermo will allow us to inspect the upper .050" of the material, I think this would be a good substitute for search peening.
Thoughts? Alternative suggestions?
Thanks you.
