Is the best hard steel knife REX 121?

Where does cruwear stand on that list of hardness? According to crucible it can be anywhere from 61-65 HRC but I believe that's referring to the ingot version. Would the CPM version have any difference?

I know that this stuff hold an edge like crazy, so far, it's preformed better than the piece of M4 I have.
 
The Mastiff said:
They make some knives in HAP 72 at about rc 68-69 :http://www.fendrihan.com/kiya-westernstyle-kamagata-knife-hitachi-steel-blade-p-2328.html
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That's an interesting find, thanks. Too bad both HAP72 knives are short ones :(

The Mastiff said:
There are much higher priced knives than this in much simpler alloys. Still, I'd like to try it in a mule at this hardness.
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I suppose partly because of the brand, and another thing is Aogami/Shirogami can support very thin edges, below 10 inclusive. HAP72/Vanadis 60 is unlikely to do that, but like you said, mule would be nice for utility use.
 
I have made blades from CPM-REX-121, CPM-REX-T15, CPM-s125v and also CPM-15v, ‘in my opinion’ due to the very high carbide contents they are not the kind of steels which hold a hair popping edge for any length of time but they are very hard after HT and wear resistant, they would be suitable for the ‘tooling industry’.
Not every steel I experiment with works best for a knife blade perhaps this is why I enjoy working with different steels in my quest to find out what works better that others.
 
farid. said:
I have made blades from CPM-REX-121, CPM-REX-T15, CPM-s125v and also CPM-15v, ‘in my opinion’ due to the very high carbide contents they are not the kind of steels which hold a hair popping edge for any length of time but they are very hard after HT and wear resistant, they would be suitable for the ‘tooling industry’.
Not every steel I experiment with works best for a knife blade perhaps this is why I enjoy working with different steels in my quest to find out what works better that others.
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Thanks for ringing in. :)

Personally I think the A11 steels are at the top of the usable heap for knife steels. :thumbup:

That's based on what I have personally seen.
 
How are you my friend,

This is the reason why I decided on the CPM-10v steel for the Spyderco K2, it is a good steel, I would highly polish the edge as it would improve its performance significantly.

Ankerson said:
Thanks for ringing in. :)

Personally I think the A11 steels are at the top of the usable heap for knife steels. :thumbup:

That's based on what I have personally seen.
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farid. said:
How are you my friend,

This is the reason why I decided on the CPM-10v steel for the Spyderco K2, it is a good steel, I would highly polish the edge as it would improve its performance significantly.
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I figured that was why you chose it. :)

I have tested A11 from 320 grit to .5 Micron and it's really very adaptable because it's so fine grained. :)
 
Ankerson said:
...They are the whole reason why I started testing knives in the 1st place back in the late 70's....
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I thought you were a part of giant knife industry conspiracy to keep people away from real performers like 420, 1095 and promo bad stuff like k294, etc.

Ankerson said:
I have tested A11 from 320 grit to .5 Micron and it's really very adaptable because it's so fine grained. :)
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And speaking of k294 and 10V, I had pretty good results with 320 followed by few strokes on 0.50mic diamond charged leather + leather strop, vs. 320 + plain leather strop.
 
Gator97 said:
I thought you were a part of giant knife industry conspiracy to keep people away from real performers like 420, 1095 and promo bad stuff like k294, etc.


And speaking of k294 and 10V, I had pretty good results with 320 followed by few strokes on 0.50mic diamond charged leather + leather strop, vs. 320 + plain leather strop.
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Yeah really. LOL :D

I bet you did. :)
 
What a great resource this forum is. I want to look into every blade suggestion made. I have never heard of most of them. Thank you all for your help and input which I will research. Thank you especially farid for your insight and knowledge of these steels. farid, you named several steels which you have used, I would like to persue these. Can these be bought? I have many d2 knives which I love, but wanted to try something more challenging. I don't know how to find a farid knife or what styles he makes. If farid or anyone can help me with this, I will appreciate it very much. Thank you all for such really good information and insight. This has been a valuable thread for me.
 
I want to also thank Ankerson; Jim's Knife Test and Reviews. Thank you Jim along with all of the other knowledgeable steel blade experts. I will take everything into consideration. I have all of the recommendations down and now will do the research and I will post it when I decide. This is really a fascinating study for me. Farid's and Jim's reputations are well known now and I will give great weight to their knowledge and studies. Everyone else seems to know much more than I about this and it make me more determined to challenge hard steel. Crazy maybe, but one of these will be the future of knife blades. Thanks again for sharing your great knowledge of knife blade steels.
 
I think the biggest thing to keep in mind in asking this question is what is the purpose of the knife? If you want the hardet knife just to have the hardest knife just to see how hard a steel can be that is one thing, but if you want a knife thats going to hold the longest edge then that's a different thing entirely a lot more goes into it than just having a high RC. I know someone in some thread somewhere (could i be more specific?) reference a metallurgy forum and i bet those guys could give you a ton of input too.
 
Here is what I would like to recommend to you.
Grind a blade from CPM-4V, send it to my good friend Brad at Peters heat-treating, heat treat at 1950F then with a triple temper at 1000F to 1025F 2 hours each cycle, that will give you around 62rc or at 1050F triple temper 2 hours each cycle and that will give you around 60rc.
Just to be clear Crucible recommends 2 tempering cycles, for 3v and 4v I do three cycles but that is just the way I do it, all my D3 tool steel BladeSports competition choppers also get three 2 hour cycles as well.
I think if you try a CPM-4v blade at 62rc with a convex grind, zero edge you will be impressed with the results, work the edge to a high polish at least a 4k water stone, try a piece around 3/16” thick, a thicker blade isn’t always better. You will also be impressed how much you can actually bend 4v before it breaks, if you know you will need a tougher tool then heat-treat to 60rc instead. Hope this works for you.





sawgrass said:
What a great resource this forum is. I want to look into every blade suggestion made. I have never heard of most of them. Thank you all for your help and input which I will research. Thank you especially farid for your insight and knowledge of these steels. farid, you named several steels which you have used, I would like to persue these. Can these be bought? I have many d2 knives which I love, but wanted to try something more challenging. I don't know how to find a farid knife or what styles he makes. If farid or anyone can help me with this, I will appreciate it very much. Thank you all for such really good information and insight. This has been a valuable thread for me.
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farid. said:
Here is what I would like to recommend to you.
Grind a blade from CPM-4V, send it to my good friend Brad at Peters heat-treating, heat treat at 1950F then with a triple temper at 1000F to 1025F 2 hours each cycle, that will give you around 62rc or at 1050F triple temper 2 hours each cycle and that will give you around 60rc.
Just to be clear Crucible recommends 2 tempering cycles, for 3v and 4v I do three cycles but that is just the way I do it, all my D3 tool steel BladeSports competition choppers also get three 2 hour cycles as well.
I think if you try a CPM-4v blade at 62rc with a convex grind, zero edge you will be impressed with the results, work the edge to a high polish at least a 4k water stone, try a piece around 3/16” thick, a thicker blade isn’t always better. You will also be impressed how much you can actually bend 4v before it breaks, if you know you will need a tougher tool then heat-treat to 60rc instead. Hope this works for you.
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Thank you Farid, your time your good advice is very much appreciated. You are gracious to give of your time and experience so willingly and I thank you for it.
 
Thank you Bladeforums, Jim and Farid for this wealth of information. For my own education I've done many cut tests similar to Jim's and have found very comparable results. I also have one of Farid's REX121 folders... Thanks again for making such an awesome steel available for us Farid. I'm still not sure when that steel will stop cutting, and it took me many, many hours and a diamond stone to convex the edge.

Anyway I've found that extreme wear resistance in a steel seems to come at the cost of keen edge holding (keen being a subjective assessment). Keep this in mind when looking at different steels. If anyone knows of a high wearing steel that keeps it keen edge, please let me know. I've found an excellent balance of that in M390. My REX121 although nearly impossible to dull, does not take a particularly fine edge. Neither does my Vanadis 10 or S110V. All good steels, don't get me wrong, but not as good as M390, 3V, S35VN and other lower carbide steels in fine edge capabilities.

For hardness...I'd have to ask why the OP was looking for the hardest steel. Not saying he shouldn't, just wondering why he is looking for it. It might help the forums help him.
 
Gunsnknives said:
Thank you Bladeforums, Jim and Farid for this wealth of information. For my own education I've done many cut tests similar to Jim's and have found very comparable results. I also have one of Farid's REX121 folders... Thanks again for making such an awesome steel available for us Farid. I'm still not sure when that steel will stop cutting, and it took me many, many hours and a diamond stone to convex the edge.

Anyway I've found that extreme wear resistance in a steel seems to come at the cost of keen edge holding (keen being a subjective assessment). Keep this in mind when looking at different steels. If anyone knows of a high wearing steel that keeps it keen edge, please let me know. I've found an excellent balance of that in M390. My REX121 although nearly impossible to dull, does not take a particularly fine edge. Neither does my Vanadis 10 or S110V. All good steels, don't get me wrong, but not as good as M390, 3V, S35VN and other lower carbide steels in fine edge capabilities.

For hardness...I'd have to ask why the OP was looking for the hardest steel. Not saying he shouldn't, just wondering why he is looking for it. It might help the forums help him.
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Thank you for the good question. Why? Well, I would never use it, just touch it and admire it as being unusual. I don't need the brittle hardest steel, but the rare and unusual qualities make it interesting for me. It is not practical, I know. So, that is it, I think, it is there and it is rare so it piques interest. I see no practical uses for REX 121 knives, but it doesn't have to be practical or functional to be fascinating. Maybe something to show off or brag about, but then, I doubt that I will ever have one. It has been an interesting study here though and a lot of really good and practical input. So that is it, Gunsnknives and the others that have asked why. Thanks for the interest.
 
sawgrass said:
Thank you for the good question. Why? Well, I would never use it, just touch it and admire it as being unusual. I don't need the brittle hardest steel, but the rare and unusual qualities make it interesting for me. It is not practical, I know. So, that is it, I think, it is there and it is rare so it piques interest. I see no practical uses for REX 121 knives, but it doesn't have to be practical or functional to be fascinating. Maybe something to show off or brag about, but then, I doubt that I will ever have one. It has been an interesting study here though and a lot of really good and practical input. So that is it, Gunsnknives and the others that have asked why. Thanks for the interest.
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Get a cheap knife and etch or grind whatever alloy name you want into the blade. Would be cheaper and accomplish the same thing.
 
You bring up an old thread to try to sell a knife? You know if all you do is buy and sell here then a paid membership with the privileges is a good idea and well worth it. Give it a try.
 
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