06-08-2018, 01:20 AM
(This post was last modified: 06-08-2018, 11:24 PM by KnifeGrinders.)
Molybdenum
Appreciate that info, Larrin.
I understand that the volume of carbides is as important as what carbides are of, but since I could use only the knives I own and my collection of blades does not have every steel, of what I have I picked those that have close content of wear-resistant elements other than Vanadium, but couldn't equal them in chromium content. Nevertheless, chromium-rich M390 and Elmax do not fall out of the general pattern we've revealed.
When you sort them by chromium content you see no pattern at all, when you sort by carbon content you see a pattern similar to vanadium content but less regular, and when you sort by HRC you see only a hint of a tendency.
I had done all that thinking before concluded that "edge retention correlates primarily with the content of wear-resistant alloys, then with the carbon content, and finally with the HRC", but it does not correlate with the volume of chromium carbides.
Larrin, could you advise please what Molybdenum/Cobalt content in a vanadium-free or low-vanadium steel would give a carbides volume comparable to the high-vanadium steels we've tested? Would really appreciate if you could name the steels.
I need this final test as we are most curious if these Molibdenum/Cobalt steels display the same quick initial rolling as high-vanadium, or this is a vanadium-specific phenomenon.
Mark, yes all knives I sharpen on CBN wheels, my usual sequence for knives is CBN #400 >> #1000, then paper wheel with 5 micron diamonds (or felt wheel with 6 micron) - all the above at the exact edge angle resulting in a razor edge with a foil burr, which I deburr on a paper wheel with 0.5 micron diamonds at +0.4 degree higher angle. As I see it the diamonds on this final wheel cut off the foil burr at the very apex.
We revealed this +0.4 degree in our study detailed in the USA Sharpeners' Report:
http://knifegrinders.com.au/Manuals/USA_...rticle.pdf
We call it the Best Honing Angle (BHA), but actually it is gentle deburring.
Tormek confirmed later that the best honing angle on their leather wheel for chisels is by 0.46 degree higher than the edge angle; Tormek hones with 3-1 micron alumina honing paste.
If you think over our diamonds and Tormek honing paste, so different and common only by the best angle, it becomes clear that deburring at this angle goes along the very apex, giving a cleaned keen edge.
(06-07-2018, 06:50 PM)Larrin Wrote:(05-19-2018, 05:23 AM)KnifeGrinders Wrote: It is getting really intriguing what Mike's SET testing of the A2 steel hardened to a range of HRCs will show.A2 has a much lower carbide volume than Vanadis 10, M390, or Elmax so that would be expected to be a more significant difference than simply the vanadium content. M390 and Elmax don’t form much in the way of vanadium carbides but rather vanadium enriched chromium carbides. D2 has a similar carbide volume to Vanadis 10 but with chromium carbide instead. Though it is conventional rather than powder metallurgy so CPM-D2 would be a better comparison for vanadium vs chromium. Vanadis 4 would be a good comparison for lower carbide volume but maintaining the vanadium carbides of Vanadis 10.
The main lesson we've learnt so far is not to assume anything, yet I wonder if the A2 data will show similar pattern of equal initial keenness loss, but better long-run retention with the increase in HRC or not.
A2 is a high carbon and primarily Molybdenum steel, and if the pattern is different, it will tell us that what we've seen is vanadium-specific and shouldn't be generalized to other wear-resistant alloys.
Appreciate that info, Larrin.
I understand that the volume of carbides is as important as what carbides are of, but since I could use only the knives I own and my collection of blades does not have every steel, of what I have I picked those that have close content of wear-resistant elements other than Vanadium, but couldn't equal them in chromium content. Nevertheless, chromium-rich M390 and Elmax do not fall out of the general pattern we've revealed.
When you sort them by chromium content you see no pattern at all, when you sort by carbon content you see a pattern similar to vanadium content but less regular, and when you sort by HRC you see only a hint of a tendency.
I had done all that thinking before concluded that "edge retention correlates primarily with the content of wear-resistant alloys, then with the carbon content, and finally with the HRC", but it does not correlate with the volume of chromium carbides.
Larrin, could you advise please what Molybdenum/Cobalt content in a vanadium-free or low-vanadium steel would give a carbides volume comparable to the high-vanadium steels we've tested? Would really appreciate if you could name the steels.
I need this final test as we are most curious if these Molibdenum/Cobalt steels display the same quick initial rolling as high-vanadium, or this is a vanadium-specific phenomenon.
Mark, yes all knives I sharpen on CBN wheels, my usual sequence for knives is CBN #400 >> #1000, then paper wheel with 5 micron diamonds (or felt wheel with 6 micron) - all the above at the exact edge angle resulting in a razor edge with a foil burr, which I deburr on a paper wheel with 0.5 micron diamonds at +0.4 degree higher angle. As I see it the diamonds on this final wheel cut off the foil burr at the very apex.
We revealed this +0.4 degree in our study detailed in the USA Sharpeners' Report:
http://knifegrinders.com.au/Manuals/USA_...rticle.pdf
We call it the Best Honing Angle (BHA), but actually it is gentle deburring.
Tormek confirmed later that the best honing angle on their leather wheel for chisels is by 0.46 degree higher than the edge angle; Tormek hones with 3-1 micron alumina honing paste.
If you think over our diamonds and Tormek honing paste, so different and common only by the best angle, it becomes clear that deburring at this angle goes along the very apex, giving a cleaned keen edge.
http://knifeGrinders.com.au