Hand Tools

unusual toothy looking wear... *PIC*

David Weaver
..under the microscope - 1095 and 1084 have unbelievably fine looking visual wear at the outset and then all the way through. But they have far less surplus carbide than 26c3, which gets harder and has better edge strength, but it's not possible to get the grain structure as fine in a sample snap test.

The 26c3 iron in question here wears extremely evenly, but at the outset without unicorning the bevel side a bit, the initial edge seems to have a more toothy look.

I wonder if those little lines are iron carbides leaving (they're not an artifact of honing). They could potentially be a micron or a couple of microns given the excess of carbon...

....edit, while writing this, I tracked down a micrograph of 26c3, and the carbide volume is visible in carbides a couple of microns in size, just like a higher carbide volume steel that's not carbon carbides.



Others for comparison:





XHP (given the look, it's a wonder that the edge is as uniform as it is - high carbide volume, but chromium and carbon carbides (the carbon carbides get tied together with some chromium, and then the rest of the chromium roams free. One of the reasons the knife people call XHP a crappy stainless is because the carbide volume makes for low toughness (but it makes a fabulous slicer that blows away steels people think it will fail against - larren doesn't even like it). Since chromium carbide steels don't seem to tolerate hot temperatures (they will dissolve into a matrix at a lower temperature than vanadium by a lot), they don't do anything high speed that I'm aware of, but they're about as hard as tungsten carbide matrix material ( as in, the carbides are only about as hard as the whole of the matrix of "carbide" material on bits) and sharpen OK.


3v (not difficult to see why it's tough)


cpm D2 - notice how much better it is than D2. The trouble with this is that an edge durability test will find nothing different between D2 and CPM D2. If you're actually making things, the fact that some D2 bits will come off of the fine edge very early will be extremely annoying. I've never seen powder D2 in tools, but there's lots from some English makers of the conventional stuff (it's wear resistant - and Brent Beach's edge pictures showed just how coarsely it wears). The reason CPM isn't used would come down to one thing - cost. D2 is cheap. CPM D2 is not.

Left after browsing these is some puzzlers - like why isn't 10v nicer to use when the carbide volume is low compared to XHP (which for an alloy steel, can be a delight to use):


© 1998 - 2017 by Ellis Walentine. All rights reserved.
No parts of this web site may be reproduced in any form or by
any means without the written permission of the publisher.