I doubt it. Why would you want to polish it anyways when you want to look at the fracture surface? It might be easier to turn down the radius of your specimen and do the test again. You can cut your specimen and prepare it for metallography but you would be looking for something different.

During the test you should notice any crack (or micro-cracks) appears at the surface of the specimen, this represents the criterion of failure. At such moment based on such cracks you can carry out the fracture test......... Good luck

Dear Chirag,

Once you cut and polish the specimen, studying it under the SEM and optical microscope will be essentially the same (except you will have better resolution at high magnification in the SEM). The power of the SEM is to image topological features, such as those obtained during fracture.

Since your samples have not fractured, SEM would not be very useful. You could perhaps examine the stress-strain curves and look for signs of instability. These signs could be sudden drop in load, or in case you're testing at high temperatures the features suggested in:

https://www.researchgate.net/publication/250674466_Modeling_of_dynamic_material_behavior_in_hot_deformation_Forging_of_Ti6242

If instability is indicated, then you could cut and polish the specimen and search for micro-cracks (as suggested by Haydar Al-Ethari). If you do find micro-cracks, these could be better imaged using the SEM. Additionally, if you have EDS attached, you could see if there is any change in elemental composition near the cracks - if a change exists, the micro-crack may have formed because of segregation of some element(s).

Article Modeling of dynamic material behavior in hot deformation: Fo...

Thank you all for your valuable suggestions

Dear Aasharnath,

Thanks for your suggestion,

After mechanical compression test, all of my alloy samples did not fail but for studying about some instability I cut my sample longitudinally and polished it. Then analyzed using SEM. I have seen micro cracks, few dimple zone and some porous else it is completely clear.

I do not know whether this morphology can be considered as fracture morphology or not?

Would you please guide me in this regards and send me some material related to this kind of analysis?

Thanks

As you are seeing features typical of fracture, such as dimples and porosity, I would say it can be considered fracture morphology, atleast in a localised sense.

Maybe someone else will be able to confirm this and provide you with some relevant literature.

Also, if you can upload a typical image then maybe someone with expertise in your material system can give specific inputs.

Good luck!

When you are preparing your sample by cutting and polishing, you are imposing sample prep artifacts that may have been created during cutting, grinding and polishing. For fracture fractography, you should look at the surface without any external mechanical preparation. If you had some SEM images of a cut samples before test, you can compare the before and after SEM images to see if any compression mark/induced stress region could be observed. However, it will be nothing conclusive. COuld you please let me know why you can not increase the load or change the geometry and break the alloy and do the fractography? There is a known strength of the alloy, I guess.

Hi Soud,

I tested my samples with machine's maximum capacity which is 100 kN..i can't go beyond this..so..

To open internal defects, fatigue fracture is well suited.