Steel that performs better when polished, and holds razor sharpness

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shinyshinyblades

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Jun 15, 2021
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I love a smooth push cut that feels like a laser, which you only get when you bring a blade to an extremely high polish.
I also love for a blade to retain its hair whittling razor sharpness as long as possible. I dont care how long a working or toothy edge will last.

Unfortunately most of the test and demos ive seen don't really test how long hair whittling razor sharpness is maintained.

Can anyone recommend blade steels that have these characteristics, and maybe steels I should avoid?

The only steel that i own that comes close to this description is ZDP 189 which when highly polished gives me an almost 30-40% increase in edge retention.
It also seems to keep that hair whittling razor sharpness for a much longer period than my other blades (s30V,m390)
 
If you want my opinion, maintaining hair-whittling sharpness is simple: don't cut anything else with it. cutting paper, meat, plastic, even cheese will foul the edge and make it lose it's extreme sharpness. Of course, a touch-up on leather might easily restore the edge, but I agree with the post above. Any decent carbon steel.
 
52100 is one of the finest-grained carbon steels, significantly moreso than 1095/O1/Super Blue.
(Edit: 5160 and L6 are even finer since they have basically no carbides, but they don't get as hard.)

AEB-L is definitely the reigning champ for fine grain, hardenability, and moderate stain resistance. If you want better stain resistance 14c28n is a close relative of AEB-L.

For stainless, wear-resistant "super steel" with a polished edge I'd pick CPM S35VN. Vanadis is also pretty fine-grained, but with any of the vanadium-heavy steels it's more difficult to achieve the polished edge you're after.

If you haven't read Larrin's summary of the work Roman Landes did studying thin edges, you should definitely check it out: https://knifesteelnerds.com/2018/08/27/what-is-edge-stability/
 
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are there any other powdered steels that would fit the bill?
is there no substitute for ZDP 189 in this category? I know it has a unique composition.
 
So far Kohetsu's HAP40 steel @ ~65 HRC is my current king of the hill regarding taking & holding highly polished edges (up to 1.0 micron diamond compound) at low edge angles (apex @ ~20 degrees inclusive)
Even at that hardness HAP40 can be considered quite tough, noticably tougher than ZDP-189 at the same hardness.
And also noticeably more corrosion resistant, as in pro-kitchen use it only seems to form a patina.

Example here: https://www.bladeforums.com/threads/kohetsu-hap40-santoku.1509214/#post-19911835
 
52100 is unlikely to maintain a razor-sharp edge longer than a super-high-hardness steel.
Maybe something exotic like CPM REX 121, which can hit 70+ HRC, would out-perform ZDP-189.
It may also help to have a higher edge angle (or a microbevel) in order to stabilize the edge; going too low can improve cutting performance, but sacrifices longevity (like an actual razor).
 
im seeing a lot of 52100 and aeb-l
and while these steels definitely fit the bill for taking a very refined edge, its a razor edge that doesnt last anywhere near as long as ZDP
im looking for something that is at least around ZDP level or exceeds it

i know there exist powdered steels like s90v and such, but these seem to preform worse when polished, so they dont fit the bill.

So far the only powdered steel ive used that actually sees a significant performance increase is ZDP-189, and is also able to hold that laser edge for a decent amount of time, more so than s90v, and m390.
 
kwackster said:
So far Kohetsu's HAP40 steel @ ~65 HRC is my current king of the hill regarding taking & holding highly polished edges (up to 1.0 micron diamond compound) at low edge angles (apex @ ~20 degrees inclusive)
Even at that hardness HAP40 can be considered quite tough, noticably tougher than ZDP-189 at the same hardness.
And also noticeably more corrosion resistant, as in pro-kitchen use it only seems to form a patina.

Example here: https://www.bladeforums.com/threads/kohetsu-hap40-santoku.1509214/#post-19911835
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HAP40 is definitely nice steel, but toughness to me isnt as important as edge retention. and ZDP is far superior for edge retention.

Im not sure if HAP40 improves its preformance when polished though. have you noticed an improvement in this area?
 
Super keen edges don't last long, but they will last longer with super wear-resistant steels.

My best edge-holding blade is Rex 121 at 70 Rc. Very thin. Very sharp. Cuts like a razor. Never gets dull. But that's a specialty steel without a lot of toughness.

Vanax Super Clean is a high-wear powder steel that is very fine grained and easy to keep sharp. Not an easy steel to find, but it's a wonderful EDC steel.

AEB-L is a tough steel, but won't hold an edge long. 52100 is a great steel, but it won't hold an edge long, either.

Probably your best bet would be S90V, 10V or K390 or ZDP 189 at high hardness. None will be easy to sharpen, but they will hold an edge for a long time. But the super keen edge will still not last long.

Remember that geometry cuts. Go with a thin blade with a narrow edge -- say 0.007 inches or less. Spend some time to get the apex very clean, then use a strop to maintain the keen edge.
 
AEB-L @63 RC. Did this yesterday, kinda a normal day. Cut out (4) holsters from 8/10 oz saddle leather, (18) sheaths, one from the same 8/10 oz leather, one from 8/9 oz and the rest from 7/8 oz. (37) individual pieces of leather cut. All leather premium Wicket and Craig.

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This roundknife is used almost daily and in fact is the one tool that is never put away, its always on the bench. It has to be highly polished sharp or it doesn't cut the leather correctly. I maybe sharpen it every 6 months or so, maybe. Stropping or buffing brings it back to highly polished razor quickly.
 
Do you know how your razor edges fail, do they wear out or deform? Also, how do you polish your final edge, diamonds, CBN or something else?

ZDP-189 is not a fine grained steel and it works for you so fine grain is not what you need. It has high wear resistance and gets hard so you would need something like that, but with higher wear resistance or hardness. You also need to be able to abrade vanadium carbides which you don't have to do with ZDP-189. Steels like S90V, S110V should be able to do it if your edge is not deforming, but fails due to wear. If it deforms and not wears out then maybe a steel that gets very hard is your answer. Without knowing your mode of failure or how you get your razor edge it is hard to say what would work better. If you need both higher wear resistance and hardness you will need to go to something like maxamet, z-max, 10V, 15V, m398, etc. Since you say that HAP40 lasts a lot less for you, you are probably loosing sharpness due to wear since hap40 is usually treated very hard, just a guess since I don't know which knives we are talking about. Basically it sounds like you need more wear resistance and ability to polish harder carbides. Really a bunch of guesses and assumptions, since we don't really know your sharpening, specific knives, how the edges fail, etc
 
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HAP40 needs to be around 65-66 HRC to really shine, so comparable to ZDP-189.
Given two identical Chef knives with the same sharpening angle, same grade of edge polish, same thinness behind the edge, and the same use, the HAP40 knife tends to hold that high sharpness for longer.
(based on feedback from a few Chefs i sharpen for)

ZDP-189 steel is most certainly no slouch (one of my own EDC knives for many years is a modified Spyderco Endura ZDP-189), but it tends to (micro-)chip sooner, and the apex will definitely corrode faster from citrus fruits (especially lemons) and tomatoes.
There's a reason why on certain kitchen knife forums HAP40 has been nicknamed "voodoo steel".
 
ace said:
Do you know how your razor edges fail, do they wear out or deform? Also, how do you polish your final edge, diamonds, CBN or something else?

ZDP-189 is not a fine grained steel and it works for you so fine grain is not what you need. It has high wear resistance and gets hard so you would need something like that, but with higher wear resistance or hardness. You also need to be able to abrade vanadium carbides which you don't have to do with ZDP-189. Steels like S90V, S110V should be able to do it if your edge is not deforming, but fails due to wear. If it deforms and not wears out then maybe a steel that gets very hard is your answer. Without knowing your mode of failure or how you get your razor edge it is hard to say what would work better. If you need both higher wear resistance and hardness you will need to go to something like maxamet, z-max, 10V, 15V, m398, etc. Since you say that HAP40 lasts a lot less for you, you are probably loosing sharpness due to wear since hap40 is usually treated very hard, just a guess since I don't know which knives we are talking about. Basically it sounds like you need more wear resistance and ability to polish harder carbides. Really a bunch of guesses and assumptions, since we don't really know your sharpening, specific knives, how the edges fail, etc
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They all fail by wearing out.
I use only diamonds all the way down to 0.1 micron on a guided system, that I DIY'd it has a sliding rail that moves laterally and a pivot arm.

I have s90v, and when I go down to 0.1 micron it actually does somewhat worse then if I just gave it a coarse finish. I have seen reports of the same thing. Im getting approximately a 10-15% decrease in preformance when they are polished. wheter that is a signifigant difference or just normal variability i do not know for sure. With ZDP at least the difference is large enough that im more confident.

the M390 class seems to vary enough for me to feel that coarse or polished doesn't make much difference.

most of the more exotic steels like ZDP and HAP40 are spyderco stuff. I have a few benchmades, and kizer in m390 s90v.
The thinnest knives I have are the delica and bugout.
The chaparral is thinner but it only comes in CTS-XHP, which actually preforms like a lesser ZDP for me. It seems to take and hold a razor edge decently and going down to 0.1 micron seems to improve its preformance.

I have yet to try maxamet, z-max, 10V, 15V, m398, k390.
Im cursious if anyone has experience with these and if going down near the 0.25-0.1 micron level improves the performance, and if they prefer a smooth polished edge or coarse one.
 
From my experience I have witnessed the following:
From greatest to least:
Percentage Improvement on edge retention when polished:
ZDP189 -> HAP40 -> M390 -> s90v/s110v -> s30/s35vn

Steels that hold the razor hair whittling edge the longest
ZDP189 -> M390 -> HAP40 -> s90v/s110v -> s30/s35vn

AEBL and 52100 i left out, because although they should significant improvements when polish the edge doesn't last long enough.
Im wondering if there is any knife steel that can be put on the left of ZDP for both cases.
 
shinyshinyblades said:
...
Steels that hold the razor hair whittling edge the longest
ZDP189 -> M390 -> HAP40 -> s90v/s110v -> s30/s35vn
...
Im wondering if there is any knife steel that can be put on the left of ZDP for both cases.
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Rex 121 at 70 Rc, for sure.

In Larrin's data, ZDP 189 at 65 Rc gets 720 TCC.

Rex 121 at 71 Rc gets 1,010 TCC
 
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