cold worked austenitic SS B/H curves

[dgallup]

I'm trying to do a 2D FEA analysis of some devices that have deep drawn austenitic stainless steel components. If these parts were annealed I would use a constant permeability of about 1.005 or just leave them out of the analysis completely. However, since they have a lot of cold work they are more permeable.

The problem I'm running into is the data I've got gives single values of permeability as a function of percent cold work, ie 304 is 1.16 at 30% cold work & 2.30 at 50% cold work. 304L can go even higher, 8.5 at 50% cold work. Using constant permeability like that is creating obvious computational errors at high induction levels. With a constant permeability of 1.005 I'm getting 0.5 T in the SS while a constant permeability of 3 yields 1.2 T and 8 gives over 2 T in the same spot. Those values are obviously not right.

So I need to use a non-linear B/H curve for these austenitic stainless steels like I do for the ferritic materials. The problem is, I don't have such curves. Does anybody have a reasonable B/H curve for cold worked austenitic SS or know where to get such data?

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[EdStainless]

You want to know what the bad part is, it will vary considerably.
Slight changes in chemistry or temperature prior to cold work will have significant impact on the martensite formation.


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[dgallup]

I'm sure it will but I need some place to start. Surely this stuff has to saturate at relatively low flux density levels which isn't happening with a constant permeability model.

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[MagMike]

The cold drawing is converting some of the austenite to martensite, producing a magnetic response. Since most of the martensitic grades saturate out in the 1.7T range, I'd suggest making a hybrid magnetization curve with an arbritrary permeability and a saturation level near 1.7T (maybe lower). It certainly would not be perfect, but it is a start.

 

[dgallup]

MagMike - I'm planning on taking an approach along those lines. However, since only a (small?) portion of the the austenite is converting to martensite, I would think 1.7 T is too high. I'd love to have some actual data. I've contacted KJS Magnetics but I doubt they can measure my actual parts (too small). Hopefully they can provide some data on bar samples.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[EdStainless]

I have samples of cold drawn tube, but alas no way to measure them.

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