What are the darker regions in annealed 1018 steel?

[snowJT]

The following is an image of 1018 steel I annealed, image size is 100x zoom

Just wondering what the darker regions are... perlite?

http://i21.photobucket.com/albums/b300/DrGame/181879b.jpg

 

[daysyworld]

Hi, steel 1018 usually has between 0.15-0.20 % of Carbone, yes, the darker regions are perlite

 

[Cerpin Taxt]

Sure, dark structure is Perlite.
Carbon fraction is given in alloy specification

1018 $$\rightarrow$$ 0.18% Carbon

And ... Annealing Treatment ( Total Annealing) may result in perlite + ferrite.
It's shown in your micrograph
Dark - perlite
Bright - Ferrite