I have wondered about doing this for mower blade edges for durability.
Not the whole blade, as you don't want a hard blade that fractures on impact with something. But just the sharpening edge.
I've been trying to make the edges more durable too. A harder edge, will crack more in these applications. I did hear a super smart guy at work basically solve this issue, using a neat tool.
So instead of heating the steel of the blade, the machine deposits on the surface of the blade, a layer of tungsten wherever you aim it, its a concentrated point of application. You coat both sides of the entire blade edge, and you will have a surface that is extremely hard, insanely wear resistant, and the blade would retain its sharpness until you whacked a rock or something that would put a huge chip in the blade edge.
Last season I sharpened my blade edges on my John Deere about every 4 mows. I did randomly check the edge by just lifting the tractor up, and testing with my finger... My Brand new at the begining of the season blades were slightly rounded by the third use. Blamed it on sticks in the spring, and still sharpened them. Continued through entire season checking the edge condition each pre-sharpen of the blades. All the blades had rounded dents in them routinely after 3 to 4 uses, only one rock chip in one of the edges, it was not able to be sharpened at the chip, too much material was gone.
SO my observation is that the tip of the edge would wear down on the grass, sand, basically it was enough to round them off, very uniformly, over the entire edged surface on the blade.
The machine is expensive.
It takes lots of technique to work
It takes a lot of smarts to use it effectively
It would work best with brand new blades. The paint on at least the edges of the blades would have to be completely removed, and the metal surface would have to have any oils or other types of contaminates would need to be removed. Then, you get someone with skill and the tungsten material, and you coat the edges up. Hopefully you keep and angled edge, don't get the halfmoon shaped dents in the edge, and maintain a nice edge needing zero sharpenings throughout the season.
I am forgetting a drawback of this process, there is a clear reason why we didn't do it before.. I can't remember the issue, but it may have been something with the maximum thickness of each layer you can apply? IDK but the idea was hot in our group, and the guy was supposed to dig up / find the old machine in his garage, he is a real hoarder. All I know is that a tungsten coating on blade edges on paper would be very wear resistant. Much more resistant that the steel they use in the blades.
I'm sure part of the simple tech reason for the blades, is that they're well, just blades on a mower. Lots of people go years without even checking the condition of their blades. Tons of people just don't even care if the grass has a good cut pattern on the edges. Lots of simple just lets do it, don't care users out there. I bet the cost/sales values are iffy. I only know of three people that are smart enough and care enough to do it, I guess there is not enough demand for the product to create the solution.