Any simple way to guess steel type?

Hi Again!

I recently made a trip to the nearby metal scrapyard to just buy a forklift tine, some structural steel, and bought some plate while I was at it.

But I noticed that one of the big plates I bought is significantly harder to grind. And I absolutely can not drill through it. I know I can spend money to get it tested. And I can still try the harden then smack test. But I'm not really looking to make knives out of it. It cuts fine with a torch, and seems to weld easy enough with 7018.

It just now occurred to me that it might be heat treated to begin with? But it was on a stack of other identical plates, and just sold as regular "steel."

So any cheap and easy ways to guess / test what it might be? I'm mostly just sating my own curiosity.

My best advice is to search YT(or just a general internet search) on how to identify steel with a spark test. You'll find plenty of ways to test the steel for composition and hardness. But, unless you submit it for a formal composition analysis, you can only guess. What you bought is called "mystery metal", so unless you can find something that ties it to a specific alloy, there really is no definitive way of know what you have.
I wonder if the just surface is hardened.

Etching will give indication of what might be in it too. (I.e. 80crv2 etches lighter than 1095 b/c of alloying).
Kevin Harvey from Heavin Forge has sample pieces of known steel. He proposes that you compare the sparks generated from the unknown steel with that off the known steels to try and determine the correct steel.