Sharpening S30V blade

David,

My only tested high Va blades is GB M4.
Initially, maintained with white compound + Martin's Washboard, it got sharp, good to be EDU. However it lacks the smoothness to shave my face like cheaper steel (8Cr13MoV) on same compound. Tge 8Cr even got smoother after testing it with green, which also worked well with 52100.

Yesterday I made time & broke out the diamond paste + thin cardboard (those from kleenex), 12, 6, 3, 1, 0.5, 0.25, 0.1um. Tested the M4 on them (stopped at 0.25). It's a world of difference.

My finding mirror the carbide tear out vs fiamond shaping you mentioned.

Thanks for sharing the 'why', otherwise I might still be stubbornly clinging to simple compound (black, white, green). It's no wonder some people stays with simple steel. It's easier to maintain (polished that is) with just old green (CrO?).

@ Vijay, I try copy paste that URL with the code:
[img]http://i.imgur.com/pwcYNF4.jpg

Back to topic, I don't have S30V, but if the Va is the same hardness like M4, I'd suggest get some diamond if you want 1um or better refinement.
 
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Thank you Chris, I would really appreciate that. I like the 8cr13mov too, but Did you know that It's made with scrap metal. Yup...
 
Vijay,

Please share the source that 8Cr is made of recycle material. I'm guessing that in this era of recycle, almost anything is recycled, it depends on the processing & impurity resulting from it. Some might be recoverable (like iron, not sure, not a metallurgist).
 
Will research, I've heard it being mentioned before and It's plausible as there was a time off great slowdown in Steel production and access coking coal production in China, 8cr13mov is more than 1% carbon. Also China import alot of scrap metal from Malaysia. I try and get some facts, sorry for sounding so sure about the facts.
 
Thank you Chris.

Chris "Anagarika";13236555 said:
David,

My only tested high Va blades is GB M4.
Initially, maintained with white compound + Martin's Washboard, it got sharp, good to be EDU. However it lacks the smoothness to shave my face like cheaper steel (8Cr13MoV) on same compound. Tge 8Cr even got smoother after testing it with green, which also worked well with 52100.

Yesterday I made time & broke out the diamond paste + thin cardboard (those from kleenex), 12, 6, 3, 1, 0.5, 0.25, 0.1um. Tested the M4 on them (stopped at 0.25). It's a world of difference.

My finding mirror the carbide tear out vs fiamond shaping you mentioned.

Thanks for sharing the 'why', otherwise I might still be stubbornly clinging to simple compound (black, white, green). It's no wonder some people stays with simple steel. It's easier to maintain (polished that is) with just old green (CrO?).

@ Vijay, I try copy paste that URL with the code:
[img]http://i.imgur.com/pwcYNF4.jpg

Back to topic, I don't have S30V, but if the Va is the same hardness like M4, I'd suggest get some diamond if you want 1um or better refinement.
Click to expand...
 
A little late to the party, but thought I'd toss this in anyway. Have had pretty good luck working higher carbide steels using silicon carbide both in grit from a stone,and in various blends of graded SiC as I tested my home brew compounds. I have no idea what size the carbides in s30v are supposed to be, but I am not seeing any tear out, nor when working with D2 (though D2's chromium carbides are not quite as hard as SiC, so not surprising). Had to take a closer look as the conventional wisdom doesn't quite support my observations...

Anyway, have been doing a bunch of follow-up as time permits on an s30v Bos HT. Best results at very high polish have come from EEF diamond plate followed by diamond lapping film. Stropping with 1u diamond paste was barely distinguishable in use from my silicon carbide compound, though 1u lapping film did work very well and produced a much higher polish than the 1u compound. This steel is quite tough once the particles size drops down into the single digit micron range. Easier and a bit faster with diamonds, but mostly when using lapping film. On the strop, both minerals seemed to have some issues though worked fine.

Last test I did was to simply do my usual Washboard (had to use 800 grit 3M instead of the 600 grit Gator brand), in any event, a medium finish on the wet/dry, then a heavy dose of WB SiC compound on a sheet of paper. Did just like the 'best practices' video and rubbed off most of the binder and larger abrasives - finished off on the fine stuff. I had to use a bit more elbow grease, but then the WB is made for a heavy hand. I generally work on grinding media at between 1 and 4 ozs, on the WB with paper and compound it can go as high as 4 lbs. Had to lean on this one, but it came around nicely. Could just treetop some leghairs and I don't believe I could have gotten it much finer with this set-up (I grabbed one of the cosmetic blems from my latest run of boards because they're just plain nicer than my old prototype).
The D2 came around a bit nicer, treetopping leghair with authority.
I have no idea how this would work on s90 or s110v, but the s30v edge doesn't really look a whole lot different from other edges at this level of finish - no evidence of carbide tearout, or even much in the way of edge micro rounding etc, at least that can be seen with an optical microscope. The micron calibration strip upper left is just under 4u at 400x, and 1.5 at 1000. Not exactly sure what is going on, but for a fairly refined edge the SiC appears to capable of playing ball a bit longer than the conventional wisdom might allow.

s30v_400_2_Cal_zps2e61cb03.jpg


s30v_1000_3_Cal_zps8ed01af1.jpg


And the WB - finally pouring my compound into a nice mold, no more lovin' spoonfuls!

0227041910_zpsa3ecccc9.jpg
 
HH, Thank you for this work. I'm not sure what a vc tear-out would look like either. Still, a 800 grit refined edge looks unrefined under magnification. DM
 
Good work & nice pic, thanks Martin/HH!

Just like art, I interpret/view your micrograph a little diff than your. S30V VC avg size around 2um (according to Crucible). 4% V can easily map to every 7um x 7um (~50um sq) one VC should be present. I marked a few of my interpretation to your 1K pic - where I think carbides interacted with SiC + heavy (burnishing) pressure.
s30v_1000_3_Cal_zps8ed01af1.jpg

I wonder the surface etch with FerricChloride, carbides might be more visible.
 
bluntcut said:
Good work & nice pic, thanks Martin/HH!

Just like art, I interpret/view your micrograph a little diff than your. S30V VC avg size around 2um (according to Crucible). 4% V can easily map to every 7um x 7um (~50um sq) one VC should be present. I marked a few of my interpretation to your 1K pic - where I think carbides interacted with SiC + heavy (burnishing) pressure.
View attachment 419278

I wonder the surface etch with FerricChloride, carbides might be more visible.
Click to expand...

Blunt, from what I can tell, it might take some sort of electrolytic process to etch VC, I can't find a straight answer without paying for it. Normally the sample has to be worked down to "smooth" to get good resolution between carbides and the steel matrix, so would have to finish to a .2u surface which would defeat the purpose.

Your map might be a fairly accurate representation, I really don't know. Certainly at 400x there are inclusions of some sort that aren't visible on carbon or simple stainless at that magnification. They almost appear to be a mix of ribbon shapes and smaller specks? In any event there is nothing remotely in the range of 2u defects along the edge - at these magnifications it would be impossible to miss, though there could very well be much smaller tear outs which would only become visible at higher magnification - the Father in Law told me 1000x was really just a good starting point for studying cutting edges...

I recall an earlier conversation with you where we (I) speculated that as the micron size of the carbides falls the need for diamond or CBN on these steels might drop somewhat - though still recommended if only for the toughness the Vanadium imparts as an alloying agent and not for the carbide content.

Martin
 
HeavyHanded said:
Blunt, from what I can tell, it might take some sort of electrolytic process to etch VC, I can't find a straight answer without paying for it. Normally the sample has to be worked down to "smooth" to get good resolution between carbides and the steel matrix, so would have to finish to a .2u surface which would defeat the purpose.

Your map might be a fairly accurate representation, I really don't know. Certainly at 400x there are inclusions of some sort that aren't visible on carbon or simple stainless at that magnification. They almost appear to be a mix of ribbon shapes and smaller specks? In any event there is nothing remotely in the range of 2u defects along the edge - at these magnifications it would be impossible to miss, though there could very well be much smaller tear outs which would only become visible at higher magnification - the Father in Law told me 1000x was really just a good starting point for studying cutting edges...

I recall an earlier conversation with you where we (I) speculated that as the micron size of the carbides falls the need for diamond or CBN on these steels might drop somewhat - though still recommended if only for the toughness the Vanadium imparts as an alloying agent and not for the carbide content.

Martin
Click to expand...

As I understand it, that's actually what Crucible intended as the goal of their CPM process (in part), in pursuing a small-as-possible target size for the carbides to ensure easier grinding on steels like these. At some point, the decreasing size of the carbides becomes insignificant with regard to ensuring a fine edge on a cutting tool. The steel still retains high wear-resistance, because the carbides are just as hard. From a sharpening standpoint, the smaller size makes them less of an obstacle in making a cutting edge as narrow & sharp as can be, at the apex. Less of a need to thin/shape the carbides themselves, if they're already small enough to 'fit' into a hair-popping edge profile. If the extremely hard carbides don't have to be abraded, then the larger volume of the (much softer) matrix steel is the only thing dictating what abrasives can be used; and that's not really an obstacle.


David
 
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The interesting thing here (to me) is that while there are apparent cavities where a carbide has presumably been worn free, they are much smaller than the rated size for these carbides. There are neither 2u defects in the exposed edge, not are there visible 'lumps' in the surface where a carbide is anchoring the surrounding steel. Either the Bos HT creates smaller carbide formation (if that's possible), or the SIC can work these carbides down to a pretty small size before they pop out (my theory). It is my opinion they might just as well be worn free by diamond on a strop as any other abrasive, though I have found (like Chris) that alumox is really lacking on these high carbide steels, even the ones with high chromium carbides. That might also be an effect of the alloying properties rather than the carbides - I don't know enough to make a call. Another consideration is that the tear out removal of carbides from stropping cannot be any more aggressive than the tear out from moderate to rough use concentrated right on the apex, yet these steels seem to excel at rough use...

For a truly high polish on s30v, higher than my "utility" SiC compound, the 6u/1u diamond lapping film on my Washboard did a nice job - better than my DMT EEF even followed by 1u diamond paste on strop. With a small splash of soapy water it really felt just like a waterstone. I'll have to take a few more pics when time allows.

All said and done, it seems to prefer a medium grit finish in much the same way a high RC carbon steel prefers a finer finish.
 
Vijay,

I actually joined Blade Forums to respond to your post. You seem most sincere, plus I also do a lot of business with the RMAF. So I kind of owe you.

I use an Edge Pro. I use it on classic stainless, Japanese high carbon, as well as powdered metalurgy blades. WRT steels with moderate Vanadium like S30V the Shapton stones should work like a champ. If you want to geek out, stop the Shaptons at 5K, switch to diamond, and continue until your arm gets tired. I own a few of the EP glass plates and put 3M diamond lapping films on them. I use 30u and 15u for shaping (both self-adhesive) and then run down through 6u, 3u, 1u, 0.5u, and 0.1u depending upon how I feel that day. From 6u down uses water tension to stick to the glass, no adhesive required.

No Edge Pro? No problem. The diamond films can be applied to any substrate. I buy mine at at PSIDragon. Given Malaysia's involvement with high tech you might be able to find the stuff in your own back yard.

All of my work has been on HItachi Aogami Super and HAP40. I looked at my new Spyderco S30V and S110V knives and felt no fear. Another day at the office.

Cheers,

Rick
 
HeavyHanded said:
It is my opinion they might just as well be worn free by diamond on a strop as any other abrasive, though I have found (like Chris) that alumox is really lacking on these high carbide steels, even the ones with high chromium carbides. That might also be an effect of the alloying properties rather than the carbides - I don't know enough to make a call.
Click to expand...

I found this peculiar and wanted to test it. So, when my Bos heat treated S30V blade wouldn't slice newspaper I sharpened it on Only a Norton 1985 era IB-8 fine India stone. It responded very well and could work up a burr and remove it with just normal sharpening. No added elbow grease. I removed all the burrs just on the stone as I didn't have a strop. The edge on this steel is now very clean and will cut newspaper both with the grain and across, easily. A nice sharp edge. So, the powdered steels with vanadium are capable of being sharpened on a Norton fine India. I'm becoming more certain these vanadium carbides are not as hard as some sites state and the India stone more capable. DM
 
David Martin said:
I found this peculiar and wanted to test it. So, when my Bos heat treated S30V blade wouldn't slice newspaper I sharpened it on Only a Norton 1985 era IB-8 fine India stone. It responded very well and could work up a burr and remove it with just normal sharpening. No added elbow grease. I removed all the burrs just on the stone as I didn't have a strop. The edge on this steel is now very clean and will cut newspaper both with the grain and across, easily. A nice sharp edge. So, the powdered steels with vanadium are capable of being sharpened on a Norton fine India. I'm becoming more certain these vanadium carbides are not as hard as some sites state and the India stone more capable. DM
Click to expand...

The only area where I've noticed the AlumOx not performing well in s30v (or D2 for that matter) was in a stropping compound, and that is still pretty subjective - it did polish up the bevel nicely but there was a difference in quality of the cut compared to the SiC. The Norton India stone is one tough cookie.
 
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