I find that as I get older...dragging stuff home that I do not have a specific use for is counter productive....it's time and energy to make space for it, move it when I clean (which is not too often...prolly cause of all the "finds" I have carted home...lol) and then dream up ideas to prove to myself that I didn't waste a bunch of time and energy no matter how cheap it was...well, you see where I'm going here...lol
I've used them at work, there threading dies for pipe. probably made by Ridgid.
they are good steel, it takes a lot of threading before they dull but I have no idea what there made of.
personally, unless I had a forge and power hammer I'd pass on them.
maybe Ed or another smith here will have a better answer.
Too short, wide, and thick for stock removal. Forging them out to a usable piece of steel to start a blade with will take a lot of time and effort. Depending on the alloy content they could have a narrow heat range for forging. Heat treating is "your guess is as good as mine". I'd pass and let him sell them for scrap.
I have one of those and there great....for tapping small holes mostly in folder making. I believe mine's a #45
I believe that one pictured says it's for 1/2" and up. that would be great for serious production tapping but for the occasional hole that you would need to use taps that large, I'd just hand tap them.
I could be mistaken but that's what it looked like.