×
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

Non-magnetic properties of Hadfield manganese steel

Non-magnetic properties of Hadfield manganese steel

Non-magnetic properties of Hadfield manganese steel

(OP)
I am working on a project that has cast Hadfield manganese steel (ASTM A128 Gr. A) parts.
One of the main properties required is that the magnetic permeability needs to be less than 1.2mu.
The foundry that is casting the parts for me has experience with casting Hadfield for wear resistant parts, but they informed me today that the castings are not passing the permeability test.
What processes affect the magnetic properties of the Hadfield?
The castings have been heat treated but I do not know what temperature or how long it they were held at temperature. I am assuming (dangerous word) that the heat treating procedure in the MIL specification was followed.
If the heat treat was done correctly, what else could affect the magnetic properties?
 

RE: Non-magnetic properties of Hadfield manganese steel

What parts and application please. Hadfield steel,as you might know is work hardenable. Any factor contributing to raise of Ms temperature will make it magnetic. Please check the heat treatment cycle and also the microstructure. However,I stress once again that this alloy being nonmagnetic is short lived. any impact on the part,will tend to harden it therby rendering it magnetic.

 

RE: Non-magnetic properties of Hadfield manganese steel

They may have 'fixed' their shot blasting and are now working the material too much.
They may also be shaving the chemistry too much.  It might be inadvertent as there are other austenite stabilizers other than Mn (Ni, Cu, N, C) and reduction in these could result in higher perm.

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

RE: Non-magnetic properties of Hadfield manganese steel

(OP)
arunmrao; the end prouct is a boat anchor.
It appears that heat treat did play a role in this.
A keel block was poured and sections were cut off for testing the physical properties. The cut off sections did go throught heat treat with the rest of the parts.
The problem is that the remaining keel block that the founrdy was testing for the internal section permeability properties had not been heat treated.
Hopefully the issue has been resolved.
Thank you for your input.
Best regards, David

RE: Non-magnetic properties of Hadfield manganese steel

David,can you please explain why you need nonmagnetic properties for a civilian boat? Also how will the work hardening happen in this alloy for it to be exploited?

I have been involved with military applications where magnetic permeability ,is of extreme concern.

RE: Non-magnetic properties of Hadfield manganese steel

(OP)
These are for the military. Minesweepers I would guess.

RE: Non-magnetic properties of Hadfield manganese steel

That answers all my concerns. Thanks

RE: Non-magnetic properties of Hadfield manganese steel

Another possibility is segregation during the solidification process. This can lead to "hot spots" during testing.

Cold work or strain hardening in general is a prime suspect. As it was pointed out that the introduction of strain could cause the formation of martensite... which is magnetic.

RE: Non-magnetic properties of Hadfield manganese steel

If you look at the Fe-Mn-C phase diagram it is possible to have ferrite - austenite - carbide at RT. Most likely, during solidification, the carbides precipitate out along grain boundaries versus ferrite and this results in poor ductility until heat treatment is performed - solution anneal and quench.

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