No sharpen draw knife

I thought some people might be interested in my drawknife. It never dulls. Ever.

This is a picture (below) of one of my draw knives. I have three but this one is special and very, very different. It was made around 1976 and has been used a lot. The thing is, I can’t dull it, and I can’t sharpen it. Now, I’ve never tried purposely to dull it. I’ve used it mostly to carve guitar necks in mahogany and maple. And I’ve used it on other things too but always respectfully. I never tried to carve bricks with it.
It’s history is that it was made by my brother a long time ago. He was a nuclear pipe welder at the Portsmouth Naval shipyard in Portsmouth NH. He worked with lots of exotic metals for 30 years which is probably what caused his lymphoma a few years ago. Sometimes he had a little time on his hands at work. (federal job).
One day he came home with this drawknife. He had sharpened it at the yard when he made it. Actually, I don’t think it’s sharpened. I think the metal edge was cut that way by machine. It’s not razor sharp but just about as sharp as a chisel after you’ve touched it up then used it on a project. You know not tip-top sharp but pretty good. I used it awhile then tried to sharpen it. I used the traditional methods. I have a variety of stones, but to no avail. I put files to it and even a brief shot at a grinding wheel. I haven’t any diamond stones and have never tried diamond so I don’t know if that would do anything. And as far as I know, any material, like metal filings that is produced when I try to sharpen it comes from the sharpening device.
If memory is good (which it usually isn’t) the metal is something like nickel-cobalt alloy, used either in pressure fittings around the reactor or possibly nuclear sub hull metal. I used to listen to stories about metals and what they were used for but all the names are a jumble in my head.
So, this little draw knife stays as sharp as it was 30+ years ago getting no sharper and no duller than it was.
I’ve included a couple of pictures. If it doesn’t look very sharp it’s because the shiny knife edge is very old. The shiny doesn’t show any longer.

-- The smell of wood, coffee in the cup, the wife let's me do my thing, the lake is peaceful. http://gagnerwebsite.com/Deceiver/Craftsman_on_the_lake/Craftsman_on_the_lake.html