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?
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
RE: Non-magnetic properties of Hadfield manganese steel
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
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
I have been involved with military applications where magnetic permeability ,is of extreme concern.
RE: Non-magnetic properties of Hadfield manganese steel
RE: Non-magnetic properties of Hadfield manganese steel
RE: Non-magnetic properties of Hadfield manganese steel
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
Michael McGuire
http://stainlesssteelforengineers.blogspot.com/
RE: Non-magnetic properties of Hadfield manganese steel