Hand Tools

Subject:
short answer...
Response To:
Re: Photos for bill.. ()

David Weaver
I think I may have said on here that suspecting it's carbides is more likely, but not particles. In powder metals, I don't know.

Carbides are bigger than the original powder metals, though. Larrin's micrograph page (which I linked a few times) shows carbides on microgaphs with a micron scale bottom right.

It's not that easy to find someone telling what their powder particle size is - I see a document from the 1970s (the era of 3V development and probably 1st gen PM steels) stating 4-100 microns. 3V would've been expensive and probably on the low end, but it only has a small amount of vanadium in it, so it doesn't matter (vanadium by itself makes small carbides and there's not much of it).

What sizes are the carbides for PMs? if you eyeball larrin's micrographs, you could say 1 to 10 microns in general on the longest length. niobium and vandium in small amounts, very small carbides. A whole lot of vandium and chromium, bigger carbides (not sure how the three play with each other as some will combine and then the rest will go free).

So, the voids in the pictures are consistent with the micrographs.

as far as the diamond particles, they leave a scratch pattern a little finer looking than an 8k waterstone, but deeper (so the edge sharpness and durability wasn't quite as good). I suspect the reason the pattern looks finer is because they're more closely graded than the particles in cheap waterstones.

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