New Knife Steel Ratings by Knife Steel Nerds

[Wartstein]

I agree with what pretty much everyone it seems that Magna Cut will be just a great, and on a very high level well balanced steel!

Still: As one who is not concerned with corrosion resistance, I wonder what steel Dr. Larrin could design even better in "just" the combo of edge retention and toughness, if not putting a so very high emphasis on rust proofness too...

[Larrin]

I agree with what pretty much everyone it seems that Magna Cut will be just a great, and on a very high level well balanced steel!

Still: As one who is not concerned with corrosion resistance, I wonder what steel Dr. Larrin could design even better in "just" the combo of edge retention and toughness, if not putting a so very high emphasis on rust proofness too...

I didn’t put a high emphasis on corrosion resistance, that was just the result from eliminating the chromium carbide.

[Josh1973]

I am - again - surprised how relatively "bad" REX45/HAP 40 fares. Especially how really not spectacular its toughness actually is. Of course I don't doubt the results at all (!), but this is different to what - also experienced - knife users always tend to say and also different to my own experience.
M4 seems to be the clearly better choice here: About the same edge retention, noticeable tougher.

…

I think Spyderco ran their Rex 45 too hard. Larrin tried to replicate the Spyderco heat treatment, which basically means that it wasn’t tempered for long enough to achieve an more optimal level of toughness. Tempering REX45 to 64-65 HRC would have resulted in a better balance of properties, in my opinion. If Larrin ever decides to optimize the heat treatment for REX 45, I think you will see a more desirable balance of properties.

I think most Japanese knife makers that use HAP40 (Hitachi equivalent of REX 45) temper it down to about 65 HRC. So, Spyderco’s heat treatment is going to result in much lower toughness than what is commonly achieved with the steel, and I have no idea why they decided to do that.

Well put and agreed. Some people on this forum act like REX45 is garbage steel on here. Well I have a Native Chief that has still yet to need sharpening from EDC use Involving cutting branches and breaking down cardboard boxes. But I don't use my folders to stab steel drums or baton oak logs anyways. So I am not concerned with the toughness issue of REX45 at higher Rockwell. It does not take a metallurgist to know that running a steel at high Rockwell will result in better edge retention but sacrifice toughness. And running a lower Rockwell will result in the exact opposite. I do agree that perhaps Spyderco should have ran the REX45 3-4 points lower on the Rockwell.
I never thought I would see the day junk 8CR13MOV would be praised on this forum while REX45 would be shamed.

[Wartstein]

I agree with what pretty much everyone it seems that Magna Cut will be just a great, and on a very high level well balanced steel!

Still: As one who is not concerned with corrosion resistance, I wonder what steel Dr. Larrin could design even better in "just" the combo of edge retention and toughness, if not putting a so very high emphasis on rust proofness too...

I didn’t put a high emphasis on corrosion resistance, that was just the result from eliminating the chromium carbide.

Thanks for the clarification!

I naturally assumed that high corrosion resistance must have been a main goal, since it is so extremely high.
Even more amazing, since you did actually NOT highly emphasize this..

So if you were to design a steel where corrosion resistance is not a concern at all (or lets say would be high enough at the A2-ish level), but the combo of edge retention / toughness should be the best possible: You´d go with a high speed / high alloy tool steel I guess?

[Gtscotty]

Spyderco has a good reputation for delivering knives with properly treated steels. I've never had a ton of money, and I don't have Larrin's expertise, so I buy Spyderco knives. I bought a few ZTs too, they seem to have a good reputation. I'd trust Buck, because the people doing their heat treat is well known. I don't have many Benchmade knives, but I'd imagine they are also OK.

It wasn't that long ago that manufacturers started using better grade steels, and until there are more tests run on the various knives, I'll just stick with what I know.

I agree. Instead of worrying about how steels compare when processed sub-optimally, it makes far more sense to me to compare well done samples of each and then only buy from companies with a reputation for putting in the effort to consistently produce optimal blades.

[Larrin]

So if you were to design a steel where corrosion resistance is not a concern at all (or lets say would be high enough at the A2-ish level), but the combo of edge retention / toughness should be the best possible: You´d go with a high speed / high alloy tool steel I guess?

MagnaCut has the same edge retention-toughness combination as 4V and Vanadis 4 Extra and they have a similar microstructure. So there doesn't appear to be an automatic advantage to being non-stainless. 4V and Vanadis 4 Extra still have higher potential hardness (66+ Rc) which is where the hardness-corrosion resistance balance comes in.

I wouldn't bring in high speed steels, necessarily, into this discussion as they have a similar problem that stainless steels have. With stainless steel you are balancing another property on top of the others we already need to balance, corrosion resistance along with hardness, wear resistance, toughness, etc. With high speed steels you are also balancing another property along with the others: hot hardness. You are somewhat limited in design with the need for high Mo/W just like with stainless steels you are limited because of the need for high Cr. The tradeoffs are different, however.

[Karl_H]

Well put and agreed. Some people on this forum act like REX45 is garbage steel on here. Well I have a Native Chief that has still yet to need sharpening from EDC use Involving cutting branches and breaking down cardboard boxes. But I don't use my folders to stab steel drums or baton oak logs anyways. So I am not concerned with the toughness issue of REX45 at higher Rockwell. It does not take a metallurgist to know that running a steel at high Rockwell will result in better edge retention but sacrifice toughness. And running a lower Rockwell will result in the exact opposite. I do agree that perhaps Spyderco should have ran the REX45 3-4 points lower on the Rockwell.
I never thought I would see the day junk 8CR13MOV would be praised on this forum while REX45 would be shamed.

I don't think anyone is "shaming" REX45. I think it is a fine steel for knife blades. Since Spyderco doesn't share any information regarding their heat treatments, I do think it is fair to wonder how well optimized Spyderco's heat treatment is and what use each steel is best suited for, given the heat treatment. When other knife makers are heat treating the same steel to a different hardness range, it begs the question.

Spyderco markets REX 45 as "A true steel connoisseur’s blade material, REX 45 is an ideal steel for [Insert Knife Name Here]".

In my own use, I have found that the low toughness limits the use of REX45 at lower edge angles (15 dps) for cutting rubber inner tubes and whittling wood. Slightly disappointing, but not entirely unexpected. I am not talking about "stabbing steel drums" or "battoning oak logs".

[z1r]

What actually surprised me was how well 8Cr13MoV faired. It gets so much crap talked about it but it holds an edge so much better than many HC steels and is definitely more corrosion resistant. And, in the Spyderco lineup, it's very affordable.

I think otherwise decent, affordable steels like AUS-8/8Cr13MoV and 440C develop a bad reputation partly because the market is flooded with cheap knives in those steels that have been poorly heat-treated or have really terrible edge geometry.

Spyderco does a good job with its 8Cr13MoV knives, but there are so many companies out there that regularly pump out 8Cr13MoV knives with edges that are ground terribly, & therefore not giving the steel the chance to perform anywhere close to its potential.

I have to agree, the 8Cr13NoV in my Byrds and Tenacious are head & shoulder above the same steel in another maker's knife I own. Night and day.

Agreed. I keep saying the CE Resilience in 8Cr is a very high performance knife for the $$. Takes a fantastic edge and holds it well enough for my day to day chores.

I keep my CE Tenacious in my desk at work just because, in a pinch, I can sharpen it on the bottom of my coffee cup if need be.

[Doc Dan]

Finally, a video on my level.

[Sharp Guy]

I am - again - surprised how relatively "bad" REX45/HAP 40 fares. Especially how really not spectacular its toughness actually is. Of course I don't doubt the results at all (!), but this is different to what - also experienced - knife users always tend to say and also different to my own experience.
M4 seems to be the clearly better choice here: About the same edge retention, noticeable tougher.

…

I think Spyderco ran their Rex 45 too hard. Larrin tried to replicate the Spyderco heat treatment, which basically means that it wasn’t tempered for long enough to achieve an more optimal level of toughness. Tempering REX45 to 64-65 HRC would have resulted in a better balance of properties, in my opinion. If Larrin ever decides to optimize the heat treatment for REX 45, I think you will see a more desirable balance of properties.

I think most Japanese knife makers that use HAP40 (Hitachi equivalent of REX 45) temper it down to about 65 HRC. So, Spyderco’s heat treatment is going to result in much lower toughness than what is commonly achieved with the steel, and I have no idea why they decided to do that.

Well put and agreed. Some people on this forum act like REX45 is garbage steel on here. Well I have a Native Chief that has still yet to need sharpening from EDC use Involving cutting branches and breaking down cardboard boxes. But I don't use my folders to stab steel drums or baton oak logs anyways. So I am not concerned with the toughness issue of REX45 at higher Rockwell. It does not take a metallurgist to know that running a steel at high Rockwell will result in better edge retention but sacrifice toughness. And running a lower Rockwell will result in the exact opposite. I do agree that perhaps Spyderco should have ran the REX45 3-4 points lower on the Rockwell.
I never thought I would see the day junk 8CR13MOV would be praised on this forum while REX45 would be shamed.

I'm on this forum several time per day I don't think I've ever seen anyone imply that REX45 is garbage steel. I have no clue where you got that impression. You're all welcome to express your thoughts and opinions but, if I recall correctly, everyone was excited and happy that Spyderco was running REX45 at a higher hardness. It actually felt like HAP40 was now inferior because it couldn't be run as hard due to the SUS410 outer cladding. I like HAP40 and I've never felt that way but I'm pretty easy to please. This is the first time I've actually seen anyone complain that they're running REX45 too hard. So it would seem to me that we have the best of both worlds. You can buy knives with REX45 at a higher hardness or HAP40 with more toughness. How fabulous is that?

[Airlsee]

Since I don't fabricate knives or depend on knives for my livelihood, the arguments in threads like this are only good for amusement.

I'm not going to get hung up on Spyderco's specific HRC numbers per steel/per batch. If you need to cut all day buy Maxamet or K390. M4, HAP40, Rex45 all work very well for my uses, and I'm glad that I've got multiple examples of each. Until one of them starts blowing out giant chips or rolls the entire edge in heavy EDC use, I'll be perfectly happy with all 3 and their varying HRC's.

I do wish I had a HRC tester just for fun though, LOL!

[Accutron]

This is the first time I've actually seen anyone complain that they're running REX45 too hard. So it would seem to me that we have the best of both worlds. You can buy knives with REX45 at a higher hardness or HAP40 with more toughness. How fabulous is that?

^^^ This.

After about a year of using a Rex PM2, I sold all of my Seki HAP40. The lower heat treatment wasn't the only issue, but it was definitely a contributing factor.

[James Y]

For those of us where corrosion resistance is of primary concern it’s good to see so many stainless steels we know side by side for toughness, edge retention and corrosion resistance. Wish H1 was included like others in the corrosion resistant 10 rating: LC200N and Vanax. I have some knives in H1 and LC200N but not Vanax yet. I’m much more familiar with those in the 9-9.5 corrosion resistant rating like: M390/20CV/204P (favorite EDC steel for corrosion resistance and edge retention in a small 3” blade length folder). Of course, MagnaCut is begging to be tried.

Interesting. I thought S45VN was supposed to have an advantage in toughness over S30V, but this chart shows them both rating a 4 in toughness.

I’m sure that actual use in various blades/grinds, heat treats, etc., will yield results that differ from the chart to varying degrees.

Jim

What does S45VN bring to the table that we don't already have, except for being a new steel? I mean seriously. Cool looking knife, though.

See article:
https://knifesteelnerds.com/2019/11/01/ ... 5vn-steel/

S45VN offers better corrosion resistance and toughness than S30V with the same edge retention.

This is what the S45VN Article said:

“The main changes we expect from S45VN vs S35VN and S30V are an improvement in corrosion resistance due to the increase in Cr of about 1%. We expect a reduction in toughness when compared with S35VN because of the increase in total carbide content. The design including niobium and nitrogen additions should help maintain toughness similar to or better than S30V.”

“S45VN has only slightly reduced toughness when compared with S35VN, and S45VN is an improvement over S30V, particularly when hardness is factored in:”



“The S45VN datasheet provides a number for CATRA edge retention relative to 440C, which it lists as 143%. This is in comparison with 440C which is 100%, S30V at 145%, and M390/20CV at 180%. However, the datasheet has an asterisk next to the 143% value and says that it is “based upon market feedback.” These estimates should perhaps be treated with some suspicion as the S35VN datasheet has the same asterisk for its 145% value which puts it at the same level as S30V, but independent experiments put S35VN around 132% at 61 Rc [8]. The same study found values for 61 Rc S30V at 149% and 61.5 Rc M390 at 179% [8], which are similar to those given by Crucible (though for 20CV rather than M390). However, Bob Skibitski of Crucible confirmed to me that the 143% number is based on actual CATRA experiments. Interestingly, the S45VN datasheet has a newly adjusted CATRA value of S35VN of 140%, better reflecting the somewhat reduced edge retention of S35VN when compared with S30V.”

Thank you!

I am interested in trying out S45VN, as I really like S35VN, and I like S30V, but a bit less than S35VN. The differences between 30 and 35 are not that great for me, but there is just “something” about 35 that I like more than 30. We’ll see about 45.

Jim

[z1r]

I never thought I would see the day junk 8CR13MOV would be praised on this forum while REX45 would be shamed.

I don't think anyone is shaming Rex45, certainly not me, but I also think it unfair to categorize Spyderco's 8Cr13MoV as junk. I only wish I had pulled the trigger on that ugly mint green Para 3 in M4 so I could conduct my own comparison of M4 vs Rex 45.

[Sharp Guy]

I'm not going to get hung up on Spyderco's specific HRC numbers per steel/per batch. If you need to cut all day buy Maxamet or K390. M4, HAP40, Rex45 all work very well for my uses, and I'm glad that I've got multiple examples of each. Until one of them starts blowing out giant chips or rolls the entire edge in heavy EDC use, I'll be perfectly happy with all 3 and their varying HRC's.

I do wish I had a HRC tester just for fun though, LOL!

I used to have access to one several years ago and it was great. Now that I'm really into knives I miss it

You've reminded me that my good friend has a portable one. I need to see if I can borrow it

[zuludelta]

Interesting.  I thought S45VN was supposed to have an advantage in toughness over S30V, but this chart shows them both rating a 4 in toughness.

I’m sure that actual use in various blades/grinds, heat treats, etc., will yield results that differ from the chart to varying degrees.

Jim

I think the ratings represent a ballpark range of possible values, and thus S30V & S45VN having the same toughness ratings might mean that you won't find an appreciable difference in their toughness in use (assuming consistent heat treatment & grinds), even though there may be a measurable difference in a controlled testing scenario.

The measured difference in toughness between the two is probably small enough so as not to be practically (or maybe even statistically) significant.

[Larrin]

The ratings are all rounded to the nearest 0.5 because higher precision than that would be more misleading than useful. S30V was rounded up and S45VN was rounded down.

[Soanso McMasters]

The ratings are all rounded to the nearest 0.5 because higher precision than that would be more misleading than useful. S30V was rounded up and S45VN was rounded down.

I was looking at toughness between BD1N and S110V to get an idea of what to expect with 110. Are they rounded up or down?

[Fireman]

With the .5 ratings, there are 20 possible rankings. This is a good rating system for ease of data consumption for the masses. Knife nerds may want a scale out of 100 but the variables of heat treat, edge profile etcetera make it problematic for stats. I like that Dr. Larrin shows the range potential on the graphs with the lines. I find that quite useful. I support the “Larrin Scale” but I like the steel comparison graph overlays with the “Line of potential” on them.

[Karl_H]

If you really care about the details, skip the ratings and look at the actual data that the ratings are based on.