×
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

Porosity in CA6NM Castings

Porosity in CA6NM Castings

Porosity in CA6NM Castings

(OP)
thread330-217250: Nitrogen in CA6NM

The above thread references Nitrogen solubility in CA6NM. We are having porosity issues in casting with thinner walls (0.5"). I am having our heat tested for nitrogen content. In the mean time can any one comment about what percentage of Nitrogen would cause porosity in CA6Nm castings? Also, if the nitrogen in the heat is higher than desired, is there any way to remove this nitrogen during melting?

Thank you,

--------------------------------------
There is always some thing better out there...
Mahadhatu

RE: Porosity in CA6NM Castings

mahadhatu;
Could you describe your melting practice for these castings?

RE: Porosity in CA6NM Castings

(OP)
Melted using air melt induction furnaces. We either use fresh materials (100% Chrome, Ni, 100% Mo and Low carbon steel) or ingots purchased from as master melter. According to the Certs from the Master melter, the average Nitrogen in the ingots is 0.02%. We do not have the capability of measuring Nitrogen in house so we have never measured it in our heats.

We use FeSi, Mn and Fe-Ti as deoxidisers.   

--------------------------------------
There is always some thing better out there...
Mahadhatu

RE: Porosity in CA6NM Castings

More likely it is moisture.  These alloys will hold a lot of nitrogen in solution.
How are you shielding the alloy during melting?

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

RE: Porosity in CA6NM Castings

(OP)
Ed,

This problem is evident in CA6NM castings with thinner walls (0.5") and not in thick wall castings. If the same configuration is cast out of something like 316SS we don't have this issue.
If moisture was the main cause, all of out castings should have the same problem which is not the case.

Thank you for your comments.  

--------------------------------------
There is always some thing better out there...
Mahadhatu

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