Initial Impressions-AR RPM9 Steel and Blades

Joined
Feb 4, 2022
Messages
535
I own two knives in this steel: CJRB Crag and Artisan Cutlery Arroyo. Both have seen medium use since purchase. After moderate dulling of the edges, I sent both to the whetstones (1000 and 6000 grit) and then to the leather strop using 1 micron (approximate) green compound. I was very impressed at how easy this was, each blade cooperated with small effort only. I only post this because this steel is so new and there is very little info out there regarding its properties and performance in the field.

If you have experience with this steel, feel free to post your experiences. For me, so far I am impressed.
 
I sent some knives over to Outpost 76 when this steel debuted. He noticed some issues in sharpening. Given, these were "day 1" drops so maybe they didn't have the heat treatment dialed in yet. In testing a 1" section of blade at 15dps versus cardboard, performance wasn't much different from ordinary 9Cr18Mov. That was a little underwhelming given that this was PM steel based on 9Cr18Mov. What really sunk it for me was how much better the Civivi and Sencut knives did with a really good heat treatment on ordinary 9Cr18Mov.

I've seen three possible benefits discussed that don't come up here. First, AR-RPM9 may have improved toughness versus 9Cr18Mov due to the powdered metallurgy. I really haven't seen that explored. Second, I've heard anecdotal reports that AR-RPM9 strops up very nicely. Third, Michael Emler noted that AR-RPM9 had better than expected corrosion resistance. Now, 9Cr18Mov already has good corrosion resistance. So that could be a thing but I haven't seen anything further about it.

 
Here is some more discussion on AR-RPM9, 9Cr18Mov, and hardness tests on some of the knives that were cut tested.

 
there is a big thread about it already :)

for a 'pm' it's rather lackluster - but decent given the low price
frankly, I prefer non-pm 14c28n
 
Thanks guys. I will check out the existing thread. I own two Civivis in 9Cr. No issues there and am really happy regarding price/value/performance. My comments above regard ease of sharpening only. I have not owned these long enough to discuss toughness, edge retention, etc.
 
I sent some knives over to Outpost 76 when this steel debuted. He noticed some issues in sharpening. Given, these were "day 1" drops so maybe they didn't have the heat treatment dialed in yet. In testing a 1" section of blade at 15dps versus cardboard, performance wasn't much different from ordinary 9Cr18Mov. That was a little underwhelming given that this was PM steel based on 9Cr18Mov. What really sunk it for me was how much better the Civivi and Sencut knives did with a really good heat treatment on ordinary 9Cr18Mov.

I've seen three possible benefits discussed that don't come up here. First, AR-RPM9 may have improved toughness versus 9Cr18Mov due to the powdered metallurgy. I really haven't seen that explored. Second, I've heard anecdotal reports that AR-RPM9 strops up very nicely. Third, Michael Emler noted that AR-RPM9 had better than expected corrosion resistance. Now, 9Cr18Mov already has good corrosion resistance. So that could be a thing but I haven't seen anything further about it.

That video reminds me of my recent experience with my Kizer in N690. I have corundum aluminum oxide whetstones in 1000 and 6000 grit. After using the 1000, the edge is nice and sharp, maybe slightly toothy, but with no apparent burr, at least to my feel. After the 6000 a burr can be felt by touch and the edge loses its sharpness using a fingernail test. No matter what I do, the burr will not release. I go very lightly on the 6000 and even switch to nothing but trailing edge strokes, to no avail. I also try the strop after the 1000 stone, and same result. It seems that the finer grit (the 6000 stone is approx. 4 micron and the strop uses approx. 1 micron compound) forms another burr and it cannot be removed. But if I return the blade to the 1000 stone, it returns to sharp and slightly toothy. I have decided that the steel is likely not heat treated ideally, or my technique may need refinement. Will continue to experiment.
 
My on EKKO is doing rather well. Yes it’s not the best steel but it’s certainly not the worst either, very good for budget knife.

Now there are random comments on both this forum and reddit claiming RPM9 isn’t actually powder steel, anyone know if this is true or not?
 
My on EKKO is doing rather well. Yes it’s not the best steel but it’s certainly not the worst either, very good for budget knife.

Now there are random comments on both this forum and reddit claiming RPM9 isn’t actually powder steel, anyone know if this is true or not?

I have no idea and I'm not sure anyone is in a hurry to get that question answered.

This steel has been out for over a year now. It didn't shake things up much. Being exclusive to the one company has been a limiting factor for interest in the steel, and I don't know how much the steel has done to promote the company. Yeah, it's a PM budget steel and I guess that's cool to have on the map. The problem is that however magical the process, it hasn't done much to rival regular 9Cr18Mov or other decent budget steels.

On edge performance, regular 9Cr18Mov with a better heat treatment from WE (Civivi, Sencut, Ferrum Forge) still holds a better edge. I've seen reports that AR-RPM9 is more resistant to corrosion but 9Cr18Mov is already very stainless. So even if true, I have to ask "by how much" and whether that actually matters to anyone. Anecdotally, AR-RPM9 is a little tougher and strops up nicely. Similarly, we are left wondering how much difference there is versus regular 9Cr18Mov--or 10Cr15CoMov, VG-10, N690, etc.--and if it's enough to be an important selling point. Better yet, how does it compare on those metrics with higher-toughness stainless choices like 14C28N or Nitro-V?
 
I have no idea and I'm not sure anyone is in a hurry to get that question answered.

This steel has been out for over a year now. It didn't shake things up much. Being exclusive to the one company has been a limiting factor for interest in the steel, and I don't know how much the steel has done to promote the company. Yeah, it's a PM budget steel and I guess that's cool to have on the map. The problem is that however magical the process, it hasn't done much to rival regular 9Cr18Mov or other decent budget steels.

On edge performance, regular 9Cr18Mov with a better heat treatment from WE (Civivi, Sencut, Ferrum Forge) still holds a better edge. I've seen reports that AR-RPM9 is more resistant to corrosion but 9Cr18Mov is already very stainless. So even if true, I have to ask "by how much" and whether that actually matters to anyone. Anecdotally, AR-RPM9 is a little tougher and strops up nicely. Similarly, we are left wondering how much difference there is versus regular 9Cr18Mov--or 10Cr15CoMov, VG-10, N690, etc.--and if it's enough to be an important selling point. Better yet, how does it compare on those metrics with higher-toughness stainless choices like 14C28N or Nitro-V?
Mine certainly strops up very nicely but yes I find myself doing so a tad bit more often than my s30v’s from Benchmade. It totally out lasts the Leatherman 420hc though. They’re my only comparison steels, I have a few Magnacut but I don’t use them too often.
 
Mine certainly strops up very nicely but yes I find myself doing so a tad bit more often than my s30v’s from Benchmade. It totally out lasts the Leatherman 420hc though. They’re my only comparison steels, I have a few Magnacut but I don’t use them too often.

It's not hard to beat the Leatherman 420HC on edge retention. Multi-tool blades are way behind the times compared to the EDC knife market. It's a step or two down from the comparison class here.

S30V should be a step up from the comparison class with AR-RPM9. I'd certainly hope it holds a better edge!

If this stuff is interesting to you, I'd definitely recommend exploring more knives in the market space where AR-RPM9 hangs out. For instance, look at Civivi or Sencut knives in 9Cr18Mov, 10Cr15CoMov (analogous to VG-10), or 14C28N; or Kizer knives in N690 or 154CM.
 
It's not hard to beat the Leatherman 420HC on edge retention. Multi-tool blades are way behind the times compared to the EDC knife market. It's a step or two down from the comparison class here.

S30V should be a step up from the comparison class with AR-RPM9. I'd certainly hope it holds a better edge!

If this stuff is interesting to you, I'd definitely recommend exploring more knives in the market space where AR-RPM9 hangs out. For instance, look at Civivi or Sencut knives in 9Cr18Mov, 10Cr15CoMov (analogous to VG-10), or 14C28N; or Kizer knives in N690 or 154CM.
Definitely interested, thank you for the recommendations.
 
I forgot I had created this thread more than a year ago. I now own 4 knives in this steel. Like Chronovore, my impression is that this steel is adequate but nothing to write home about. It does sharpen up easily and strops well. But not really noticeably different from other competing steels. Overall a competent steel, nothing bad about it given its price and market segment. I suppose when you market a "pm budget steel" it becomes too easy to expect a miracle, and a letdown is inevitable.
 
I have a CJRB Chord on the way; am i going to be disappointed? Itll only be for some general cutting nothing real heavy....
 
I have a CJRB Chord on the way; am i going to be disappointed? Itll only be for some general cutting nothing real heavy....


It'll do great for you, this kind of thread is geared towards sharpening nerds for the most part
 
I have a CJRB Chord on the way; am i going to be disappointed? Itll only be for some general cutting nothing real heavy....

Based on this thread and the other one linked previously, you should have an idea of what to expect from the steel. To sum up, it should be "okay". Edge retention won't be as good as a Civivi or Sencut in 9Cr18Mov but should still be a nice step up from 8Cr13Mov. It will probably be easier to maintain than steels like D2. For what it's worth, the corrosion resistance seems to be excellent.

The main thing, based on a dozen or so knives from this company, is to carefully check the knife when you get it. Make sure the action is smooth, lock-up is solid, there are no defects, etc.. Artisan/CJRB can turn out a well-made knife but I've also seen a lot of lemons from them. I'm also not alone in having been frustrated with their customer service. So if anything is wrong, you'll want to return it at the dealer level.

Good luck!
 
I have a CJRB Chord on the way; am i going to be disappointed? Itll only be for some general cutting nothing real heavy....
I like each of my 3 CJRBs and my single Artisan Cutlery. The quality is good for the price. The only issue I have had is with my Scoria. The liner lock has too much tension and has late lockup. It could be that the liner lock landing ramp on the tang was overcut and the liner bar had to be adjusted and bent inwards to accommodate. The practical impact is that my thumb gets sore when pressing the liner lock to close the blade. But it is safe and cuts well. Just a minor inconvenience in my book.
 
hopefully itll be nice just for occasional carry and light cutting tasks...

Assuming no defects, it should be. Expectation can have a serious impact. On the one hand, there was a lot of hype for this steel and then it felt like a whiff versus comparably priced options that were already on the table. On the other hand, this is a knife forum with concentrated interest. I was interested in the project, the idea, and the possibilities of a good PM budget steel. Of course, some people were dismissive from the start or couldn't have cared less.

In terms of "occasional carry and light cutting tasks", even lesser stainless like 12C27 or AUS-8 can be more than adequate. Think about all the guys out there still rocking 8Cr13Mov! If you get a knife you like (with no defects) and the price was right for you, consider it an extra side of gravy in the "more than adequate" category. (Sometimes, we get cutting into how much extra it is even if we might never actually notice the difference.)

Provided that you get a good one and keep it, let us know how it goes.
 
My arroyo took a good week to break in , the steel is super easy to sharpen on a sharp maker and I strop green and white and I'm good to go
 
Back
Top