×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Sample preparation of round specimen to reveal grain structure

Sample preparation of round specimen to reveal grain structure

Sample preparation of round specimen to reveal grain structure

(OP)
I want to reveal the grain structure on the curved surface of a tubular sample made of stainless steel (SS 304). In the usual sample preparation method to reveal the grain structure one needs to polish the sample flat first and then etch it. But, I want to reveal grain on a curved surface of my tubular specimen (please see attached sketch) without polishing it flat.

Can anyone suggest the appropriate sample preparation method for my application? Is electrolytic polishing suitable here?

RE: Sample preparation of round specimen to reveal grain structure

There was no attached sketch. You can have a surface polishing technique that is used for field metallographic examination (replicas). After using 600 grit a portable electropolisher is used along with electrolytic etching with 10% oxalic acid. Contact a materials lab or testing group that can do replication or field metallographic examination.

RE: Sample preparation of round specimen to reveal grain structure

So do not want to section it, or can't you?
A longitudinal section would let you examine this structure.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Sample preparation of round specimen to reveal grain structure

Do you have a scope that can build an image on the curved surface? If not, you will only be able to look at a small section of the surface, depending on the magnification and the diameter of the part.

RE: Sample preparation of round specimen to reveal grain structure

And on 304 what does the grain structure matter, it is fully austenitic.
If you are looking for carbides or twining then you likely need to do sections in order to get good enough images.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Sample preparation of round specimen to reveal grain structure

(OP)
All, thanks for your suggestions and comments. Below is the sketch (the attachment didn't go with the main post).



Actually, I'm doing tensile testing with tubular specimen both inside and outside of a Scanning Electron Microscope (SEM). SEM has higher depth of field, hence I'm expecting to see more curvature, compared to what is visible with an optical microscope at very high magnification.
Now, the reason I'm interested in seeing the grain on the curve surface is because in this way my test samples will be the same (almost) for the tests performed both inside and outside. To reveal the grain, if I polish the surface flat, this will change the cross-section of sample, and hence my inside and outside tests will not supplement each-other.

I think what I need is the sample preparation technique with the least amount of surface alteration. Off-course, I'll need to take out some material from the tube surface, but I need to keep it to minimum. Hence, I'm thinking about electropolishing.

Any suggestion is welcomed.

RE: Sample preparation of round specimen to reveal grain structure

Mechanical grinding with appropriate equipment (small grinding discs) could be enough.

With appropriate microscope does not matter the curvature to attach it and watch directly, without need of replicas.


RE: Sample preparation of round specimen to reveal grain structure

FarhanRahman
This sounds like a research project for a thesis?????

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close