×
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

ultimate strain of SS?

ultimate strain of SS?

ultimate strain of SS?

(OP)
I've been looking for the ultimate strain for some different materials and having trouble.  Particularly 13-8 H1000, MIL-HDBK-5 has a stress strain curve but it only ges up to about 1.2% strain.  They also have a "full range" but it shows the same Ramburg-Osgood curve and then at 1.2% strain the curve starts coming down.  This seems a little low for a material which is considered ductile.  Is this value right or is there another source I can check for a better stress strain curve.  As an aside mil-hdbk says the fracture strain is 10%, which I guess I believe a little more than the ultimate strain.

Thanks

RE: ultimate strain of SS?

ozzkoz,

The fracture strain is the same as the ultimate strain, which is required to be 10% for PH13-8Mo according to AMS 5629 (Table 2.6.6.0(b) on page 2-158 of MIL-HDBK-5J).  The full range curves shown in Figure 2.6.6.1.6(c) show the same thing: the H1000 specimen fractures at an ultimate strain of ~ 0.10.  Keep in mind that these are engineering stress-strain curves, and that the shape of the true stress-strain curve will be different.

 

RE: ultimate strain of SS?

You can also use other technical resources for comparing engineering stress/strain information on 13-8PH as shown in the attachment below regarding tensile elongation values;

http://www.alleghenyludlum.com/ludlum/Documents/13-8(062606).pdf

Tensile elongation (total strain to failure) in 2" gage is 14% typical for an H1100 condition.

RE: ultimate strain of SS?

(OP)
The elongation is the total stretch at fracture, I'm actaully looking for the ultimate strain (strain at ultiamte strength, or the strain at onset of necking).

I'm doing an elastic / perfectly plastic analysis and I don't think I can assume I carry the full plastic load all the way out to fracture since I'd have necking after the ultimate strain is reached.

RE: ultimate strain of SS?

Ok, I now understand what you are asking. At the onset of necking, the true strain = strain hardening exponent. If you know the strain hardening coefficient, you can use this value for the strain at necking.

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