×
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

C95800 - elongation

C95800 - elongation

C95800 - elongation

(OP)
We have a couple of heats of ASTM B148 C95800 with poor elongation (12-13% against a 15% minimum). Both have been heat treated at 675C and air cooled.

Chemistries are:

Heat 1) 1.3% Mn, 4.9% Ni, 4.35% Fe, 9.4% Al.
Heat 2) 1.15% Mn, 4.9% Ni, 4.1% Fe, 9.1% Al.

Residuals (Si, Cr etc) are all <0.01%. The tensile strengths are nicely above minimum spec.

Does anybody know of a heat treatment that we can use to improve the elongation?

Thanks

RE: C95800 - elongation

bruv:
What size are the castings? It may be that the first anneal treatment was inadequate, especially when you report that the UTS values are "nicely above" the minimum if 85 Ksi. Also, check the tensile report for any errors, I have seen this before.

Per ASM Handbook, Volume 2 (on-line), the typical annealing temperature range for C95800 is 650 to 705 deg C. I would attempt a second anneal and see if this drops the UTS and increases your elongation.
 

RE: C95800 - elongation

(OP)
Thickest section on any of the castings is 4".

I have re-checked the HT traces - times and temperatures were fine. We HT at 675C for 6hrs.

Yields were in the region of 310MPa (45ksi) and UTS for both was around 680MPa (98ksi). I have looked back in our records and these are fairly typical values.

I have already tried the re-anneal for the same time/temp combination, and then pulled the test bar myself. There was no difference in the before and after results.  

RE: C95800 - elongation

bruv;
Last item, did you verify chemical composition of the castings with your own analysis? If not, I would verify.
 

RE: C95800 - elongation

The only other thing that comes to mind is to look at the grain size of the test bars.  Is it very large?
Aren't your typical elongations about 20%?
Are you sure that the bars are machined properly, not too rough?

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

RE: C95800 - elongation

(OP)
That's our own analysis - matches that supplied by the ingot manufacturer.

Test bars were machined as smooth as we could get them. We haven't looked at grain size. Typically, elongations are around 20%.

We don't think we've done anything different this time, which is why the lack of elongation is puzzling us.

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