I Tested the Edge Retention of 48 Steels

Synov said:
It would have the highest edge retention but the lowest toughness. The same would be true at any hardness. Going softer increases toughness slower for high carbide steels.

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I am not metalurgist so maybe i read this chart wrong. It seems that 3v has roughly 15 times greater toughness than CPM 154, S35VN, K390 and even more greater then Maxamet and Rex 121? It allso seems that Maxamet and Rex121 have 3 times greater edge retention? Does it mean that Rex121 would be 3 times better in edge retention on 59 Hrc then 3V? How approximately would be Rex121 toughness on 59 Hrc against 3V? Or I asking to much? :) Thank you!
 
zorandjurkic said:
I am not metalurgist so maybe i read this chart wrong. It seems that 3v has roughly 15 times greater toughness than CPM 154, S35VN, K390 and even more greater then Maxamet and Rex 121? It allso seems that Maxamet and Rex121 have 3 times greater edge retention? Does it mean that Rex121 would be 3 times better in edge retention on 59 Hrc then 3V? How approximately would be Rex121 toughness on 59 Hrc against 3V? Or I asking to much? :) Thank you!
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I'm not sure how you got those numbers. Toughness is on the left side of the chart. The numbers near the points are hardness values. 3V is only about 3-4 times as tough as the steels you mentioned at the same hardness. Maxamet and Rex 121 have about 2 times the edge retention.

Edge retention changes similarly with hardness for most steels, so yes the edge retention ratio would remain the same at any hardness. But how toughness changes with hardness is more dependent on the steel. The toughness of lower carbide steels changes rapidly with hardness but slowly for high carbide steels. So the toughness ratio may not be the same at different hardness.

At 59 Hrc, 3V is about 39 ft-lbs while Rex 121 would be about 7-8 ft-lbs.
 
zorandjurkic said:
I am not metalurgist so maybe i read this chart wrong. It seems that 3v has roughly 15 times greater toughness than CPM 154, S35VN, K390 and even more greater then Maxamet and Rex 121? It allso seems that Maxamet and Rex121 have 3 times greater edge retention? Does it mean that Rex121 would be 3 times better in edge retention on 59 Hrc then 3V? How approximately would be Rex121 toughness on 59 Hrc against 3V? Or I asking to much? :) Thank you!
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At 59 Rc the toughness of Rex 121 would still be bad
 
zorandjurkic said:
Do You maybe know what steel could it be tougness compared to? Would be edge retention more significant than 3V? I am sorry for bothering and thank you!
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It has similar toughness to S60V. It would have about 2.5 times the edge retention of 3V.
 
If you want Rex121 you will have to accept the fact that it will not be a tough steel. All steels are a compromise of various aspects and you have to find the balance of those aspects that work best for your needs. Rex121 is never going to be tough.
 
I would also add that understanding the intended use of a knife leads to deciding what material would be best for that design. REX 121 at any hardness is not going to make a good chopper, but will make a decent EDC meat/rope/cardboard/fibrous material cutting knife. If you attempt to force a high carbide steel to act like a lower carbide one by lowering hardness, you are leaving performance on the table.
 
Why would you attempt to use REX 121 at 59 HRC? R 121 performs best at high hardness (70+ HRC). S60V is optimized at 61~ HRC (this is way understated BTW, Shawn can explain better than I, microstructure and such, HRC is only one variable). At 61 HRC S60V is at approximately 6-7 ft/lbs toughness. Rex 121 at 70 is like 3 ft/lbs or so.

Essentially, at a working hardness (optimal for cutting) S60V has double the toughness of REX 121. RX 121 will have nearly double the edge holding ability though.

In the ratings article Larrin has REX 121 at a toughness of 1 on a 1-10 scale and an edge holding at 12 on a 1-12 scale, S60V has a toughness of 3.5 and Edge holding of 7. on a 1-10 scale.

I actually prefer S90V over both of them for EDC size fixed blades.
 
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navman said:
Why would you attempt to use REX 121 at 59 HRC? R 121 performs best at high hardness (70+ HRC). S60V is optimized at 61~ HRC (this is way understated BTW, Shawn can explain better than I, microstructure and such, HRC is only one variable). At 61 HRC S60V is at approximately 6-7 ft/lbs toughness. Rex 121 at 70 is like 3 ft/lbs or so.

Essentially, at a working hardness (optimal for cutting) S60V has double the toughness of REX 121. RX 121 will have nearly double the edge holding ability though.

In the ratings article Larrin has REX 121 at a toughness of 1 on a 1-10 scale and an edge holding at 12 on a 1-12 scale, S60V has a toughness of 3.5 and Edge holding of 7. on a 1-10 scale.

I actually prefer S90V over both of them for EDC size fixed blades.
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To explain briefly. I think Rex 121 would be a great replacement for 1095 in smaller outdoor knives. It would also be a good core for layered steel. I don't know if this steel is even available in the EU or how much it costs, so I don't dare try anything. As for stainless steels, I have to admit that as a user and not an expert, I think Magnacut is a really good step forward.
 
Synov said:
Probably not. Outdoor knives should be tough. You don't want to worry about it breaking from dropping it on the ground or hitting it against something hard. Rex 121 should be used carefully.
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Imagine two to three times better edge retention than 3V and so much more than 1095 on knife like Mora Basic or companion. Well, for that Mora i will spend 100- 150eur even if it's as fragile as tempered glass. Layered blade (with two lateral layers of 420 steel, differentialy hardened) on 58/54 Hrc wouldn' be so bad :)
 
zorandjurkic said:
Imagine two to three times better edge retention than 3V and so much more than 1095 on knife like Mora Basic or companion. Well, for that Mora i will spend 100- 150eur even if it's as fragile as tempered glass. Layered blade (with two lateral layers of 420 steel, differentialy hardened) on 58/54 Hrc wouldn' be so bad :)
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Yes, that's great to have, but a broken blade is much worse than a blade that needs sharpening more often. Also, "edge retention" here refers to abrasive wear resistance, which may not be the most relevant factor in edge retention in outdoor activities. For example, hardness is much more important than wear resistance for cutting wood.
 
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Doesn't quite work that way. The outer cladding will not prevent the edge from being damaged. Really you should look at a different steel that meets your needs. For what you want, REX 121 is not the answer. BUT, if that is what you want, don't let your dreams be dreams.

Me personally. For outdoor blades (camping, hiking, carving) I actually prefer CPM 4v V4E. Better edge holding than 3V with slightly less toughness and corrosion resistance.
zorandjurkic said:
Imagine two to three times better edge retention than 3V and so much more than 1095 on knife like Mora Basic or companion. Well, for that Mora i will spend 100- 150eur even if it's as fragile as tempered glass. Layered blade (with two lateral layers of 420 steel, differentialy hardened) on 58/54 Hrc wouldn' be so bad :)
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I won't ask: "And what about Magnacut steel at 59 Hrc?" :-) Honing is excellent with a sharpening rod that is 62 Hz. I assume that sharpening is easy too.
 
zorandjurkic said:
I won't ask: "And what about Magnacut steel at 59 Hrc?" :-) Honing is excellent with a sharpening rod that is 62 Hz. I assume that sharpening is easy too.
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Running high carbide steel soft doesn't make a lot of sense.

The saying is "you are leaving A lot on the table"
Basically, you aren't making good use of that steel. You aren't going to get the performance out of it, soft. MC likes to be Harder...
 
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This chart by Dr. Larrin shows that you would not gain much, if any, toughness by running Magnacut below 60 hrc. 61/62 seems to be a good hardness for Magnacut if you want it towards the tougher side. Pushed to 64 and it beats AEB-L at 64 in toughness, but exceeds AEB-l everywhere except cost.
 
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