0.5mm grain oriented electrical steel?

[Deactivated-1]

I'm trying to figure out what material is the core in a 36w fluorescent lamp ballast... The lamination are grain oriented, but the thickness I'm measuring is 0.502mm +/- .0005mm consistently (I'm measuring in the middle so there shouldn't be any error from burrs)

I can't find any standard which fits that criteria... anything I find in that thickness range is non-grain oriented, but there's clearly the splotchy grain texture, and it's sort-of in the same direction as is the rolling direction.

[Kleinstein]

It depends on the light conditions what one sees. To me the picture is not clearly showing individual grains. The pattern may well be corrosion depending on the surface conditions. The patter could repeat from contact to rolers or similar causing microscopic cratches.

EI type cores normally don't use grain oriented material, but more isotropic matierial, at least in the plane.  The grain oriented material is used for toroidal transformers and large transfromers where the core is made from several parts to that flux can follow the preferred directions. The bend around the corners in an EI core is already not working well with GO material.

Even the normal material can have some texture from rolling. The GO material uses more controlled roling with different in between annealing. Especially cheap material may be in between with parial preferred directions and neither a strong grain orientation nor fully isotropic.

[Dan123456]

I don’t know if transformer steel is the same or not (google is telling me it is probably silicon steel) but for a lot of other steels you can polish it up then dip it in ferric chloride to see the grains.

The ferric chloride eats the different alloys / components of the steel at different rates.

That said, the grains of a lot of steels can be absolutely tiny so not sure if you will be able to see them well with the naked eye or not 

Edit: derp, you already identified it as silicon steel  Sorry, not sure how I missed that