Victor, thanks for posting on this. The reason I said universal is because there was a reference to a standardized color coding system chart that I found on the web 2 days ago but who knows what standards the MFG's use?
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My O2 is dark blue at the end.
Uddeholm steel color chart
Attachment 203702
Wordpress Color Codes | Coloring Anything
Victor, I just did some quick searching and I think your correct. Ok, so now I will try the spark testing and density methods.
But no matter what the outcome I will still be using these steels as is ! :)
All else aside, at worst, you have a lot of material for making good tools and such. Might have some folding knife blades hiding in the block of D2 if you are so inclined. :D My experience with US suppliers like Alro is that yellow on the end means 1018. The HRA(hot roll annealed) is probably 1018 too.
So far I have been working on putting together the parts for the post anvils. I now have 4 of the disc brake rotors for a base plus I have found the tubing to fit the various anvils and a guy who will do the cutting and welding ( Randy Stinar in Cannon Falls). They should be done in about 3 weeks.