×
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

1080 Steel Fine Pearlite

1080 Steel Fine Pearlite

1080 Steel Fine Pearlite

(OP)
I am looking for a Fine Pearlite stucture after a piece of rail is thermite welded.  The rail steel is essentially a 1080 Carbon Steel.  Specifically the composition is:
Weight Percentage, %
 
Carbon, C
 0.72 - 0.84
  
 Manganese, Mn
 0.70 – 1.25
   
Silicon, Si
 0.10 – 1.00
  
 Phosphorus, P
 0.02 Max.
  
 Sulphur, S
 0.02 Max.
   
Copper, Cu
 0.40 Max.
  
 Chromium, Cr
 0.20 – 0.40
  
 Nickel, Ni
 0.15 Max.
  
 Molybdenum, Mo
 0.05 Max.
  
 Vanadium, V
 0.01 Max.
  
Aluminium, Al
 0.01 Max.

Based on a CCT Diagram for 1080 steel it should be cooled from Eutectoid temp of 727°C to 25°C no quicker than 2 minutes and no longer than 166 minutes.  Does this make sense.  See attached.
 
 

RE: 1080 Steel Fine Pearlite

Yes, that would be my interpretation of the diagram, but you may want to do some experimenting and lab work for verification.  As compared to spec-grade 1080, the chemistry you have listed has boosted levels of Si, Mn, and Cr among others that could affect 'hardenability' and bias the resulting microstructure, probably toward the P+M zone.

RE: 1080 Steel Fine Pearlite

(OP)
What I don't get is the 40°C/s and the 5°C/s it doesn't match with the time scale on the x-axis?

RE: 1080 Steel Fine Pearlite

The time scale on the x-axis is just seconds (s) of time and your comparing a cooling rate of deg C/s to seconds.

RE: 1080 Steel Fine Pearlite

(OP)
Yes I understand that, I'm not that slow.  

I don't understand a) how is the cooling rate constant?

b)If we take a constant cooling rate of 40C/s, it means that from 730C to 0C, it would take 18.3 seconds.  That doesn't match the x-scale which says 10^2.

RE: 1080 Steel Fine Pearlite

The cooling rates associated with the three curves (5, 40, 140 C/s) are incorrect with respect to the x-axis.  The author and editor(s) of this textbook did not catch the error.  If you look at other CCT diagrams you can see that a cooling rate of 40 C/s is associated with the 10 second order of magnitude, not 102.

RE: 1080 Steel Fine Pearlite

(OP)
Ok so I should cool the steel from the critical temp no quicker than 10 seconds and no longer than 166 minutes?

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