Why are high end straight razors mostly made of low alloy steel?

L

Londinium Armoury

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Jun 2, 2020
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If high alloy tool/stainless steels (modern super steels) out perform more simple steels when it comes to fine edge holding. Why aren't more high end straight razors or straight razor enthusiasts and makers using them on their blades?
 
There is probably also a factor regarding carbide size and density in high alloy steels, that results is them not being able to get as fine to begin with...but I'm not a metallurgist...
 
Straight razors produce a lot more than one shave per honing. Yes they get stropped between uses but it's not like they need a loaded strop. The most shaves I went was 90 and I probably could have kept going but boredom over took me.

There are plenty of threads on the net about the struggles of honing some of these custom straights of high alloy steel. You add in that factor with most straight razor shavers preference for edges off of natural stones and simple high carbon steel will always be the most popular.
 
The low end steels are typically easier to machine, blank and sharpen/re sharpen.

Fine carbide size is the most important aspect. Finding a good balance between hardness, and small carbide size.

An added bonus, the smaller carbide size typically yields a stronger steel.

Look up Steelnerds.com article on AEBL, and it covers a good bit of the early stainless use in razors.

AEBL is a good example. Fantastic steel. Ultra fine carbide size, very tough/strong steel even at higher hardness.

knifesteelnerds.com

All About AEB-L - Knife Steel Nerds

I've gathered all of the information I have on AEB-L steel, including its history, toughness, edge retention, ease in sharpening, and other properties.
knifesteelnerds.com knifesteelnerds.com

knifesteelnerds.com

What Causes Razor Blades To Dull - Knife Steel Nerds

A recent article in the journal Science claimed that micro-chipping is the cause of dull razors. Is that true?
knifesteelnerds.com knifesteelnerds.com
 
Londinium Armoury said:
If high alloy tool/stainless steels (modern super steels) out perform more simple steels when it comes to fine edge holding. ...
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I've not seen any evidence that "modern super steel" can outperform simple carbon steel at fine edge taking and/or holding. Do you have a reference for this?
 
ToddS said:
I've not seen any evidence that "modern super steel" can outperform simple carbon steel at fine edge taking and/or holding. Do you have a reference for this?
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I did some edge retention testing which focused only on fine edge holding, the results are repeatable and my interpretation of the results is that HRC had a bigger factor in edge stability than chemical composition. 2 razorblade steels were tested and they performed average, with a score of 2-4. S30V and S35VN also under performed scoring around 4-5 (slightly better than the razorblade steels 12C27/+) Old simple carbon steel at lower HRC performed poorly. So did Japanese SK5 at lower HRC scoring 1-2. Then some simple carbon 1095 at a very high HRC (63-64+)did well scoring a 7. The steels that performed in the top 3 all had 1 thing in common, very high HRC, K390 scored a 9 but M2 tool steel at 65 HRC and Spydercos CTS XHP actually did the best. far out performing 1095 at the same HRC. Tool steels at high HRC over performed. Also Hogues cryo treated 154CM, Cold Steels AUS10 and Spyderco + Benchmades S30V all scored roughly the same. The extra carbides in S30V seemed to have no actual benefit over Hogues 154CM.
 
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Londinium Armoury said:
I did some edge retention testing which focused only on fine edge holding, the results are repeatable and my interpretation of the results is that HRC had a bigger factor in edge stability than chemical composition. 2 razorblade steels were tested and they performed average, with a score of 2-4. S30V and S35VN also under performed scoring around 4-5 (slightly better than the razorblade steels 12C27/+) Old simple carbon steel at lower HRC performed poorly. So did Japanese SK5 at lower HRC scoring 1-2. Then some simple carbon 1095 at a very high HRC (63-64+)did well scoring a 7. The steels that performed in the top 3 all had 1 thing in common, very high HRC, K390 scored a 9 but M2 tool steel at 65 HRC and Spydercos CTS XHP actually did the best. far out performing 1095 at the same HRC. Tool steels at high HRC over performed. Also Hogues cryo treated 154CM, Cold Steels AUS10 and Spyderco + Benchmades S30V all scored roughly the same. The extra carbides in S30V seemed to have no actual benefit over Hogues 154CM.
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Well, let's geek out more.

It's why we're all here isn't it?

What was the test used to see the differences and performance?

How were the knives sharpened and what angle, finish, abrasives and progression used?
 
DeadboxHero said:
Well, let's geek out more.

It's why we're all here isn't it?

What was the test used to see the differences and performance?

How were the knives sharpened and what angle, finish, abrasives and progression used?
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The test was done to see when the absolute sharpness from the apex was lost, I did it because 99% of all of the testing being done was heavily bias in favour of testing the working edge of knives. So I wanted to see what steel performed the best when it comes to how long it can hold it's absolute sharpness.
Tissue (Paper towel) was used to determine when a certain level of sharpness was lost, and when the knife no longer cleanly cut the tissue I gave it a score according to the number of cuts it made.
Vinyl floor tiles were used to degrade the edge stability, by applying around 30 lbs of pressure and running the entire knife edge along the corner of the vinyl floor tile, and after each cut into the tile an attempt to cut into the tissue paper was made.
All of the knives (around 25 different steels) were given a 20 degree micro bevel for the test, so they all had the same angle apex, they were sharpened by me with progression of stones and ceramic rod system to apply the micro bevel.
Every knife after failing the test could still shave arm hair, so the level of edge degradation was very small for the testing, for example they go from being able to whittle a hair, to only being able to shave arm hair, you wouldn't notice the difference if cutting paper before and after the test. Tissue paper is a very good material for testing an edge, because unlike card, plastic or paper that people often use, only a very sharp edge will cleanly slice tissue paper and it tells you exactly when some edge degredation has taken place
 
I agree that most testing is biased towards pure wear resistance rather than to the sort of early dulling processes that occur at higher levels of sharpness. I'm not familiar enough with all of those steels to comment on your conclusion,,, maybe comparing the same steel at different hardness levels would be easier to interpret.

At the same time, I don't see your test being directly relevant to straight razor levels of keeness or edge holding. I'm trying to imagine what would remain of a vintage hollow ground straight razor if I tried to run it through a vinyl composite tile with 30 pounds of force... probably just the spine. People do prize those extremely hard razors from 100+ years ago, but they are very fragile.

Straight razor geometry is typically 7.5-8.5 degrees per side. The apex angle for Feather Super Artist Pro and the old Gillette blue blades are/were about 10 and most modern razor blades are around 12-13. It seems you really need to keep the apex below 10dps with no microbevel to shave comfortably.

Maybe as high grit diamond stones become available more people will experiment with making razors with "super" steels.
 
ToddS said:
I agree that most testing is biased towards pure wear resistance rather than to the sort of early dulling processes that occur at higher levels of sharpness. I'm not familiar enough with all of those steels to comment on your conclusion,,, maybe comparing the same steel at different hardness levels would be easier to interpret.

At the same time, I don't see your test being directly relevant to straight razor levels of keeness or edge holding. I'm trying to imagine what would remain of a vintage hollow ground straight razor if I tried to run it through a vinyl composite tile with 30 pounds of force... probably just the spine. People do prize those extremely hard razors from 100+ years ago, but they are very fragile.

Straight razor geometry is typically 7.5-8.5 degrees per side. The apex angle for Feather Super Artist Pro and the old Gillette blue blades are/were about 10 and most modern razor blades are around 12-13. It seems you really need to keep the apex below 10dps with no microbevel to shave comfortably.

Maybe as high grit diamond stones become available more people will experiment with making razors with "super" steels.
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That was my overall interpretation of the results, that the HRC of the steel was responsible for better or lower performance of the absolute tip of the apex. It's supported by the low alloy steels at high HRC out performing the high alloy steels at a lower HRC. Also it applied in reverse as well, as the high alloy steels out performed the low alloy steels when the HRC advantage was reversed. But chemical composition does seem to play somewhat of a secondary role, and it does have an impact.
Multiples of the same steel were used at different HRC, soft D2 (running at whatever Ontario runs it at, I would guess no higher than 57-58 HRC) scored low only getting a 3, then another D2 blade running at a higher HRC over 60+ scored a 6, so it literally doubled its edge stability just by increasing the HRC by a few points.
I don't think this exact test would be good for very thin straight razors, but it could be good if the pound of pressure were lessened. I believe the results would translate and be quite consistant, but 30 pounds of pressure is too high. 3 lbs of pressure or less could be used and would still gain soem sort of repeatable results.
I'm not a big straight razor collector so I don't really have access to a large selection of razors in various exotic steel types, I would like to read or see the results if somebody else does happen to have enough razors to do the test with.
It's a very easy test to set up, the flooring companies won't even charge you for the vinyl tiles, they give them away in samples online.
 
You still making blades? Why not make the straight razors?
Londinium Armoury said:
That was my overall interpretation of the results, that the HRC of the steel was responsible for better or lower performance of the absolute tip of the apex. It's supported by the low alloy steels at high HRC out performing the high alloy steels at a lower HRC. Also it applied in reverse as well, as the high alloy steels out performed the low alloy steels when the HRC advantage was reversed. But chemical composition does seem to play somewhat of a secondary role, and it does have an impact.
Multiples of the same steel were used at different HRC, soft D2 (running at whatever Ontario runs it at, I would guess no higher than 57-58 HRC) scored low only getting a 3, then another D2 blade running at a higher HRC over 60+ scored a 6, so it literally doubled its edge stability just by increasing the HRC by a few points.
I don't think this exact test would be good for very thin straight razors, but it could be good if the pound of pressure were lessened. I believe the results would translate and be quite consistant, but 30 pounds of pressure is too high. 3 lbs of pressure or less could be used and would still gain soem sort of repeatable results.
I'm not a big straight razor collector so I don't really have access to a large selection of razors in various exotic steel types, I would like to read or see the results if somebody else does happen to have enough razors to do the test with.
It's a very easy test to set up, the flooring companies won't even charge you for the vinyl tiles, they give them away in samples online.
Click to expand...
 
I have a decent collection of straight razors and kamisori's some over 50 yrs. old and all made from traditional razor steels. I agree with the goal of high HRC and available steels of the time. The performance of these razors sharpened correctly matches or exceeds shave comfort of current safety razor blades available at least on my face. I am sure the newer steels would make great razors. I always wanted to find one made out of SG2 to see how it would hold up.
 
The only "newer" steel I would want to try a razor in would be LC200N. In fact, I probably will.
 
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