I'd be finding a piece of broken truck spring.....the multi leaf kind.....
plenty on the side of the road....lol.....
excellent quality of steel....even upto 1/2" thick.....
Can be shaped by steel cutting discs quite easily.....done right with a long tang for the hammer....
I made a 6-8"blade for my metal cutting Guillotene... done the job and never needed sharpeing over the years of daily use......the original blade was unavailable...the gulliotene is French and over 50 years old......
be interested in what D_W says.....
in the third world old truck springs are highly regarded for steel stock......making cutting tools etc...
for fun I just may try it for making a couple of large scew turning tools.....
good excuse to go to the scrappie......hahaha....
More on truck springs - grain structure generally is very compact below 0.85% carbon or so, which until there's excess carbon usually equates to high toughness (hard to break tools and knives). I've never heat treated 5160 and recall that it might have some additives in it, so I can't comment (enough to say that it'll really be top shelf just heat, quench and temper). A plain steel with nothing more than a small amount of chromium, manganese and maybe a fraction of a percent of vanadium makes for a dandy backyard steel because it's hardenable, but will not form carbides in any large amount meaning that there are no large carbides to dissolve (and no real significant need for normalization).
So, long story short, the truck spring stuff is really well thought of for utility knives, machetes, etc, and will make a usable (but not great) chisel if at the top of its hardness range). And it's cheap because someone else paid for it when they bought a car.
For woodworking in dry wood, its sucking wind a bit for anything other than axes (which you'd prefer to use in wet wood, anyway) because the lack of carbon corresponds to lower terminal hardness and fine edge holding that won't match something like O1 or whatever inexpensive 0.8-1.2% carbon chrome vanadium steel would be available.
I think plain steel in the 1-1.25% carbon range is fairly easy to heat treat (but i only think that because my test results show I can match commercial process). For some odd reason, my only 1084 samples that I've ever sent lacked toughness and were harder than expected - who knows. I think the guidance to have knife guys start on a lower carbon steel is the assumption that they'll abuse a knife and won't have the ability to normalize the metal.
That's the run down on the popularity of the lower carbon steels, though -it's because you can pretty much beat them until they're covered with dents and they won't actually break easily. Strangely, some of the higher carbon steels don't continue to get tougher if you just temper parts back further and further (so if you're hanging around in the just above saw temper range, the low carbon stuff is superior).
And lastly, I have never done site work or timberframing, so I don't know what those guys love. If the wood was wet, car springs would be fine. If it was oak and dry, I think experienced users would not like it much for trimming joints.
There's an overarching theme for some of the folks on knife forums who forge that they want an endless stream of cheap fuel and cheap steel - so scrap yard stuff remains stylish, but if you're making something fine, then it's nice to buy known bar stock from a known mill that's got a known microstructure.