The content will probably vary from one company to the next, just like saw blades will.  Al the edger blades I have ever used were so hard I hard to lower the temper cut to cut them with a dremel tool, and anneal the handles a couple of times just to bore the pin holes.  It is just a guess but I think the blades I get are 5160.  I have one knife that I skinned a couple of deer and a couple of coyotes with and it will still shave your arm.