Identifying different types of steel/cast iron

I'm not sure if this should go in this section or the metal identification section, but I found this tonight and found it very interesting so I thought I'd share. If for whatever reason you ever need to know what the different kinds of cast iron/steel are and how to identify them, this guys video pretty much sums it up. Some of y'all may already know how to tell the difference between the different types of cast iron/steel but I found it very interesting and informative. A thank you to ChuckE2009 for making this vid.

http://www.youtube.com/watch?v=cFf_x97vcQ0