I am surprised the steel is hard enough that it won't need heat treatment,let us know how well it holds up under use if you ever decide to test it.
Well since its designed more as a killing blade than for peeling taters I'm not likely to tell anyone if I ever do use it.
The Chainsaw bar it came from was designed and tempered to withstand the tremendous (or maybe TREE-mendous) forces of a twisting, settling, and sliding of a tree trunk thicker than your body. So its extremely tough and springy to avoid breakage.
As I mentioned a new file could barely cut this metal and I wore out several just doing the final shaping after grinding.
I finished the blade using progressively finer silicon carbide papers glued to flat hardwood, then Steel chalk valve polishing compound impregnating cloths tightly wrapped around flat hardwood.
The blade is actually mirror finished but the scan doesn't pick that up well.
I'd estimate that the blade as is is as hard as any pre 1960's hunting knife. Not as hard as those bolt cutting Buck knives, but adequate for practically any use you'd want to put it to within reason.
Were I to re heat treat the blade I'd cover the blade with clay and thin down the clay as the edges like the Japanese did their Samurai blades. The toughness of the blade counts more for me and it comes with the original piece of steel, otherwise I'd have annealed the steel before working with it and re tempered it later.
I've made a few knives from files by annealing the brittle steel and re tempering afterwards. They worked out well but were nothing special.
I did make one that you could whittle a steel bolt with like sharpening a pencil.
