Component failed by fatigue? 1

[Naruwan]

Hi Guys!
one of our neighouring company passed this component to us and we are figuring what caused the failure. I reckon it was caused by fatigue, but not sure. This component seemed to have a flange like piece connect to a shaft. That's where it failed. It seemed that there are concentric rings propagating from the center of the shaft. I had attached two photos, the matching surface of both the fractured surface.

Thanks!

 

[Naruwan]

This is another matching surface, the shaft part.

 

[metengr]

The fracture surface was damaged by rubbing between mating surfaces and this is the cause of the observed "tree ring" effect. These rings are not fatigue damage. Other than this, you need to clean the fracture surface and re-examine it.

 

[unclesyd]

As posted above your sample is going to require some serious preparation to ascertain the mode of failure. If you don't have the facilities you ill probably have to use a Metallurgical laboratory. Even then if may still be impossible to qualify. You will have to carefully examine the design, properties, and physical environment that the part was operating in.

 

[dik]

How would one normally clean the surface. Could this be done in an ultrasonic bath of some kind?

Dik

 

[metengr]

Yes, that is part of the cleaning process. More aggressive cleaning may be required. Unfortunately, as aggressive cleaning is used the features of the fracture surface may be lost or altered.

 

[unclesyd]

If possible it would pay to reduce the size of the specimen so a better cleaning process can be accomplished. If you can accomplish this there are several approaches to your problem that will have very minimal effect on the fracture surface.
If you can do this come back for a laundry list of solutions to clean the specimen. I would try to get both side of the break for examination jsut in case.