MONEL 400 DE-MAGNETIZING

[grandprix]

We have finish machined parts manufactured from 1/2"dia monel 400 bar. We have now found out that these parts have much more induced magnetism than we thought. The bars themselves are magnetic (I assume from the cold drawing process). The test reports show that the material has been stress relieved after straightening so I doubt whether a further stress relieve will help. Is there any way of demagnetizing these parts without a full solution anneal? I am afraid annealing may change the size of the parts.

 

[Metalguy]

Any shop which has a Magnaflux setup should have a demag. unit.

 

[GRoberts]

If you are looking to reduce the magnetic field (i.e. degaussing) the parts, Metalguy's suggestion would work. If you are talking about magnetic response, such as whether or not a magnet sticks to it, that will have no effect.

 

[grandprix]

Thanks guys. I did not realise there was a difference till I tried degaussing. I guess the only option is annealing. I will let my customer know the bad news.

 

[CalvinKelly]

Some heats of Monel 400 are magnetic, some are not. The old Huntington Alloys bulletin T-5 says the Curie temperature ranges from 20 to 50F. I recall hanging a magnet from a 400 alloy plate, then heating it just hot to the touch to watch the magnet fall off (well, really I did it just to play metallurgical games with some people). If your customer must absolutely have a metal that is non-magnetic at room temperature then he needs something other than 400 alloy. For example, if the part is to be used in seawater he might consider any one of the "6moly" stainlesses, being AL-6XN, 254 SMO or 25-6MO.

James Kelly

http://www.rolledalloys.com