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View Full Version : Thoughts on Bohler Elmax, M390 and RWL-34



marthinus
02-17-2011, 04:20 PM
It seems reading many international threads on M390 and Elmax developed by Bohler might just be the competition for many of the CPM steels developed by Crucible. I dont know who produced RWL-34 except that Des Horn and Gareth Bull are using it locally.

I have had good experience with N690. However I have seen many more 12c27 blades by our local makers (nothing wrong with it IMO). However trying to keep up with international trends, moving away from conventional steels to powdered steels are we starting to fall behind keeping with 12c27 and N690?

Here is the data

Elmax:
http://www.bucorp.com/files/UDDEHOLM_ELMAX.pdf

M390
http://www.bohler-uddeholm.co.za/english/files/M390DE.pdf
http://www.bohler-uddeholm.co.za/english/files/M390DE.pdf

RWL 34
http://www.michaelwest.dk/knive/rwl34-datasheet.pdf

Buffalohump
02-17-2011, 06:14 PM
Mart, I am trying to remember the story behind RWL 34. I know it was developed in tribute to Bob Loveless, hence the initials. I believe it is very similar to 154CM but dont quote me on that! :D

I dont know why it is that custom makers dont use more US steels, given that the exchange rate is more favourable than with Europe. Maybe some of the makers can enlighten us?

marthinus
02-17-2011, 06:44 PM
Hi Buffalohump

I dont know the full story behind it but as far as I know it is the powdered version of ATS-34. ATS-34 was 154CM competition when the steels were just introduced. Crucible then started making CPM-154 and naturally RWL-34 developed. Dont know which one came first though. That is all I know. Will be interested to hear what the experienced makers say.

One advantage to Bohler is that they have a plant/stockist in SA in Isando. That might be a factor?

Tiaan Burger
02-17-2011, 07:58 PM
I dont know why it is that custom makers dont use more US steels, given that the exchange rate is more favourable than with Europe. Maybe some of the makers can enlighten us?

I think it is due to shipping costs. It is cheaper to get steel from Europe despite the exchange rate being higher.

As to using US steels... anybody got some Chev El Camino bladesprings? :D

Buffalohump
02-17-2011, 08:09 PM
What I can tell you is that ATS-34 is the Japanese version of 154CM. I was reading the other day about it. There were some issues with 154CM at one point and many makers switched to ATS-34 because it produced a more consistent end result. The exchange rate probably had a lot to do with it. Bob Loveless was also instrumental in introducing it to the US market. He had experience with it because his knives were tremendously sought after in Japan and he visited that country quite a bit. In the 90s it was the hot steel of the day for a while. RWL-34 came later, I have an idea its a Swedish steel. I know there are guys here that know more than me about it. Harm, I'm sure, can shed some light.

What's interesting is that while many makers have moved away from ATS-34, the slipjoint makers in the US still use it a lot for some reason. I suspect because it gives a very nice finish, more so than S30V. The one to watch is CPM-154, Crucible's powdered version of 154CM. I have heard it is excellent, finishes nicely, is very tough, but still easy to sharpen. And of course, its stainless....


Hi Buffalohump

I dont know the full story behind it but as far as I know it is the powdered version of ATS-34. ATS-34 was 154CM competition when the steels were just introduced. Crucible then started making CPM-154 and naturally RWL-34 developed. Dont know which one came first though. That is all I know. Will be interested to hear what the experienced makers say.

One advantage to Bohler is that they have a plant/stockist in SA in Isando. That might be a factor?

marthinus
02-17-2011, 08:21 PM
I have read similar things on CPM-154. Seems the only difference reading on the two is a small amount more of Vanadium in the RWL-34. Seems Damasteels (Swedish) are making the RWL-34 (http://www.damasteel.com/steelgrades.html).

RWL can also take a wicked polish! Just found this picture when searching (photos belong to member knifemaniac on bladeforums)

http://lh6.ggpht.com/_fNTQZJhU31I/SpqolL07sRI/AAAAAAAAFco/xdMmI4HQMiQ/s640/DSCF3969.jpg
http://lh6.ggpht.com/_fNTQZJhU31I/SrH32iYG0OI/AAAAAAAAFhg/N2Fg00Zv9-s/s640/DSCF4177.jpg

JohanO
02-18-2011, 03:32 PM
It seems reading many international threads on M390 and Elmax developed by Bohler might just be the competition for many of the CPM steels developed by Crucible. I dont know who produced RWL-34 except that Des Horn and Gareth Bull are using it locally.

Bohler-Uddeholm actually manufactures three 3rd generation powder metallurgical steels of interest to knife makers:
• M390, for the first time available in SA, 2nd quarter 2011
• Elmax, to my knowledge unavailable in SA
• Vanax, still in experimental phase, will become available from KMTs once trails proven to be successful.

Bohler-Uddeholm is the only steel manufacturer with a 3rd generation powder metallurgical manufacturing ability.

To illustrate the significant advantage of powder steels as opposed to conventional steels, the following set of improvement is achieved, using the same steel (composed of the same elements in the same mix), but manufactured differently. The accepted differences in performance, of the exactly the same steel composition, between conventional and 1st generation is between 80% and 400%, 1st generation and 2nd generation is another 13% and between 2nd and 3rd generation another 17%. This improvement is primarily due to much purer (cleaner) manufacturing, the uniformity and size of the powder particles, all resulting in a more homogeneous distribution of elements in the steel. The 3rd generation process is distinguished by a much cleaner process, aerated gas insertion and most importantly “cold loading hipping” to eliminate thermal shock during solidification.

M390 will be available from KMTs during the 2nd quarter 2011.
RWL-34 is a Swedish steel, distributed in SA by Des Horn.

JohanO
02-18-2011, 03:35 PM
I have had good experience with N690. However I have seen many more 12c27 blades by our local makers (nothing wrong with it IMO). However trying to keep up with international trends, moving away from conventional steels to powdered steels are we starting to fall behind keeping with 12c27 and N690?

I’ll conceive that 12C27 and N690 might have been around for a while but need to point out that, as far as value for money, they will remain dominant steels for quite some time. Their manufacturing properties, results in polish ability and cutting ability can only be matched or beaten by much more expensive steels and therefore they will remain main players.

Sandvik 14C28N is probably the most modern convensional steel available in the world with the introduction of Nitrogen (the “N” at the end of 14C28N). The steel was initially supplied exclusively to Kershaw and Kai Cutlery but is now also available from KMTs.

The following quote from www.zknives.com explains the significance of Nitrogen in steel well, with the exception that this type of steel has since become available to knife makers:
“Nitrogen (N) - Nitrogen acts very similar to Carbon in the alloy. N substitutes C in small amounts(or even large, with modern technologies), for hardness. Obviously, Nitrogen forms Nitrides, not Carbides. INFI has N, and there's few more, with Sandvik being the champion having 3% N in the alloy, completely substituting C. Sadly, not available for knife makers. Because Nitrogen is less prone to form Chromium nitrides than Carbon is to form Chromium carbides, its presence improves corrosion resistance, leaving more free Chromium in the alloy. Since Nitrogen is less reactive in forming Nitrides, it can be used for added hardness without increasing carbide size and volume, e.g. Sandvik 14C28N steel.”

There are many knife steel in use in SA today and it can only get better as technology and availability improves. In Summary, the following knife steels is available from KMTs:
• 14C28N
• Panzer 36
• 12C27
• N690
• 19C27
• K110 (D2)
• K460 (O1)
• EN 42F (Spring steel)
• 5160 (Spring steel)
• M390 - 2nd quarter 2011
• Vanax - Almost, watch this space for developments.

www.kmts.co.za.

NeelsRoos
02-18-2011, 06:04 PM
Hi Johan - My thought exactly. Sometimes I think when it comes to knife steels we are trying to re - invent the wheel by adding a 0.5% of chromium and 0.2% of vanadium and market it as the best steel on the market. If there was an obvious superior steel there would not have been about 20+ Martensitic steels on the market.
Only drawback of N690 for me is first removing the "black hard skin" on the outside.
Otherwise a fantastic steel.
Neels

marthinus
02-18-2011, 06:26 PM
JohanO

Thank you for VERY informative posts!

Major
02-19-2011, 10:09 AM
Greetings all,

I primarily use Sandvik12C27 which I get from KMTs, however I recently made a USMC 1219C2 Marine Fighting/Utility replica using RWL-34. I found it excellent to work with and feedback from the client has been very good as well, here is a picture of the finished product.
134

Des Horn
02-19-2011, 11:39 AM
Hi all,

RWL34 is made by ERA steel of Sweden and sold through the Damasteel agents world wide.

To set the record straight RWL34 a powder steel had been on the market for at a guess well over 10 years before Crucible came up with CPM154. I remember, at meeting in the USA, some years back, discussing all the pros and cons of different knife blade steels, chaired by one of the crucible managers, I asked the question, “How would you rate RWL34” and his comment was “They have set the bar and we are getting there”'.

Well they have with CPM154. Many knife makers changed to ATS34 when a batch of highly finished 154CM showed small black streaks and spots. In my opinion , until the introduction of the powder steels 154CM and ATS34 were the best knife steels available. What the powder steels have achieved is mainly two fold.

1) They produce a finer grain structure due to the difference in how the steel cools for the first time. A normal billet of cast steel weighs in the region of 3 tons and takes a very long time to cool from the molten state. This slow cooling allows the chrome and Iron carbide crystals to grow. The crystal structure of an iron meteorite is an extreme example of what slow cooling does. These crystals are the weak point in the steel acting as stress risers and thus the original or starting point of a fracture line. The powder steels “if correctly heat treated" outperform the normal steels, partly due to the rapid cooling of a very small billet. Powder steel effectively consists of a 0.1mm billet of steel that is cooled in a blast of liquid Nitrogen. This is almost instantaneous so the Carbides do not have time to grow resulting in an extremely fine structure allowing for one to temper to a higher hardness and still be tougher than the normal steels.

2) The powder steels manufacturing process allows components to be evenly dispersed in the steel that would normally separate out. Here I must quote my friend Wolf Borger who explains powder steel as a soup. If a rich soup with lots of fat and meat is served hot after stirring all the components are there , but if allowed to cool slowly and frozen the components separate out regardless of how finely blended or how well it is stirred. The fat floats to the top and the meat and vegetables separate into layers. If this soup is well stirred then sprayed into a freezer each droplet will freeze with a perfect mix of the components with no separation.

CPM154 and RWL34 outperform the normal steels 154CM and ATS34 by a major amount. If you really want to see good finish in an easy to machine and grind steel just try RWL34.

To comment on them being stainless! None of these steels are STAINLESS! But only stain resisting.

All these steels effectively behave like high speed steel and have a double tempering curve but if tempered at the higher point of about 500 C rather than the normal of about 180 C they are tougher but less stain resisting. So depending on what is most important to your knife modify how you temper the steel.

Nitrobe 77, an experimental steel, that I have been using on some knives, for the last year needs to be discussed, but that is for another thread.

Remember that RWL34 is one half of Damasteel.

Des

Steven65
02-19-2011, 12:01 PM
Excellent explanation Des!
Thank you very much for posting that info. Very informative

Steven

Graham Knight
02-28-2011, 12:24 PM
When it comes to the term Powder Steels, I have noticed that the term is thrown around quite losly within the Knife Makeing industry. One must realize that as with all technology, the concept of "a spade is a spade, is a spade" definatly does not apply! There are many types of Methods of manufacturing Powder Metallurgical Steels, and over the years these methods have been refined exponentially!

Cruicible Steels utilize the Generation one process which was developed in the early 50's/60's if my memory serves me correctly. This Gen1 process by todays standards is not the most effective way to produce a Powder steel. The reason for this includes:
1. The powder is produced via an induction melting process which to the best of my knowledge is not protected from the atmposphere. This allows contaminants to enter into the melt. The melt is then top poured into a tondish. This is problematic as the "slag" is the first component of the melt to hit the tondish (as it floats ontop of the melt) and inevitably it finds itsway to the powder. The best efforts are made to prevent this which in itself is arcaic; a broom typr fixture is used to "brush" the slag back in an attempt to avoid it from entering into the powder making process.
2. Atomizing: in Generation 1 after the steel exits from the tomdish, it falls approximatly 3 stories through a nitrogen shroud. At the time this was the only known method for making steel droplets. Naturally these droplets would not be uniform in size and therefore, even before the HIPP-ing (Hot isostatic press) process, the steel would be at a distinct disadvantage.

Generation 2 Steels fixed the issue surrounding the cleanliness of the steel with respect to the slag through bottom pouring out of an EAF furnace (at the same time protecting the steel from the environment). However, at this stage the technology for controling the droplet size was not available.

Generation 3, developed in the late 80's, early 90's (estimated) resolved the issue surrounding droplet size. Because of this, and because of cleanliness and a uniform microstructure, the Generation 3 method is significantly more advanced than the other two. because of this, there is a physical property imporvement of +-30% in the annealed condition accross the board.

With the above information, i would advize that instead of chasing the next big thing when it comes to powder knife steel, that knife makers take a hard look at what they are actually purchasing. knife makers should be asking:
a) What Process am i buying into (Conventional, ESR - Electro Slag Remelted, Powder Steel)
b) What heat treatment is require to get the steel to perform properly. One can have the best steel, but be unable to carry out the correct heat treatment due to machinery constraints which will ultimatly result in a Rubish product.
c) Are you using the correct grade of material for your intended application, i.e if you are looking at manufacturing a shiny display knife, N690 will not be the best material to use as it has a distinct grain, and if you are looking to manufacture a hard working utility, 12C27 would not be the best chice as it does not hold an edge for long enough.

It is my opinion that nowerdays Marketing trumps Technology. This should never be the case! I could rename an average steel Graham2011 and with a good Marketing ploy i would be able to convince everyone of the "fact" that my new steel is the newest, latest and greatest. With the utmost respect, the Americans are the best at this Marketing tactic.

Des Horn
02-28-2011, 12:46 PM
I agree ,
There are many good steels out there but they are worth zero if not heat treated correctly.

Graham Knight
03-04-2011, 07:12 AM
There are many good steels out there but they are worth zero if not heat treated correctly.

I could not agree more! Design, Heat treatment, steel selection and knife makers skill are like the 4 legs of a table, sacrificing (only a little bit) on the one will result in a very sub standard product.

Earlier in this thread comments were made regarding "re-inventing the wheel" when it comes to steel. Lately when it comes to steels, producers have been focusing on the METHOD of producing the steel in order to come uo with a superior product. an example of this would be:
You could have 3 steels, each having the same chemical composition, however the one is a conventionally produced steel, the second would also be conventionally produced, however it is cross rolled, the third is ESR (Electro Slag Remelted) and cross rolled, the fourth would be VAR (Vacuum Arc Remelted) and cross rolled and finally the cream of the crop the PM Steels (Generation 1, 2 and top of the range 3).

Each of these steels, under chemical evaluation would not seem to have any benefit over one another, however by looking at thier microstucture and the cleanliness thereof, one would definatly be able to see (under a microscope) definate advantages yielded to the steels as one moves from 1-8.

This investment into the production route of the steel manufacturer should not be sneezed at. It is proving to be very effective and very worth while.

G

Des Horn
03-04-2011, 08:03 AM
Hi Graham ,
I agree with all that you say , what I do not understand is why so many knife makers are prepared to spend many hours making a knife and then try and save a few Rand buying a cheaper steel (But pretty good steel ) but not the best !
I am also aware of some knife makers who heat treat their blades softer than ideal (one case I know of to 52HRC) just to make finishing easier , stating that they are too expensive to be used anyway !!!!!

Graham Knight
03-04-2011, 12:40 PM
Hey Dez,

OOH dont get me started on that one, if one does the maths on steels when it comes to knife making, even if you are looking at a steel that cost R1000/kg, which would naturally be the best steels in the world (no doubt because of the price), the average weight of a blade on a average size knife i would estimate to be about 200grams (gross weight before any stock removal) this would make the cost of the best steels in the world = R200 for that piece.

Even if my weight estimations are completely off, noone can argue the fact that if you compare costs from the most expensive blade to the cheapest, the fact of the matter is that both costs are neglegeble compared to the cost of your time and labour.

So my opinion is... for goodness sakes, use the best steel available, heat treat it to the best of your ability, make it look good and then sell it for a fortune! profit margins will be allot higher in the case of the good blade material!!!

Sorry, i know i waffel a bit

marthinus
03-04-2011, 02:08 PM
Wow, Des and Graham, thank you guys for SO MUCH information! It has been really educational.

Des.

I have a Gareth Bull knife in the works using RWL-34 so will post pictures when it is done. I am really excited about it! I have 154CM and VG10 (I am very happy with these steels), but by the sound of things RWL-34 will knock my socks off! Will love to see how it holds up in my use to S30V Sebenza.

Des Horn
03-06-2011, 08:27 AM
Hi Marthinus,
So that is why Gareth came to visit last week !
This young man has masses of talent and if he can survive the first few years in the market he is sure to be around for a very long time.
Please post the pics when you get them.
I am convinced that at this time RWL34 is up with the very finest all round knife steels available.
(lets consider NITROBE 77 as still too rare to be put into the mix)
VG10 is a great steel and CPM154 is far superior to 154CM.
I still chuckle over the man from crucibles comment on ZDP189. "It appears to be a type of D2 on steroids" . But recently I have heard complaints of edge chipping.
How would you rate your S30V by Chris , do you "Use but not abuse" your knives?
The question is because a well known friend in the USA has stopped using it as a result of too many complaint as a result of edge failure.
I have some heat treated blanks from him in S30V that I am playing with.
Plan to make myself a carry knife and not abuse it but work it very hard!

HeartCoppi
03-06-2011, 08:33 PM
Hi all,


2) The powder steels manufacturing process allows components to be evenly dispersed in the steel that would normally separate out. Here I must quote my friend Wolf Borger who explains powder steel as a soup. If a rich soup with lots of fat and meat is served hot after stirring all the components are there , but if allowed to cool slowly and frozen the components separate out regardless of how finely blended or how well it is stirred. The fat floats to the top and the meat and vegetables separate into layers. If this soup is well stirred then sprayed into a freezer each droplet will freeze with a perfect mix of the components with no separation.


Des

Really great way of explaining the concept.

mete
03-06-2011, 10:00 PM
For those who use steels with secondary hardening do you temper at 200 C or 540 C and why ?

JohanO
03-07-2011, 06:24 AM
For those who use steels with secondary hardening do you temper at 200 C or 540 C and why ?

Generally:

The initial temper band offers the best combination of wear resistance and corrosion resistance
The second temper band offers the best combination of wear resistance and toughness


When the knife / knife application demands toughness, the secondary temper curve offers a significant advantage.

Beware, included with the second temper curve is the "temper embrittle zone". should you enter this, your steel will scatter like safety glass under heavy loads / operations.

Here we need to be steel and application specific and stick uncomfortably close to the manufacturers specifications (TTT Diagram) or you will soon advice everybody to stay away from the secondary temper curve.

ChrisB
03-07-2011, 07:17 AM
Hi Neels, just leave the N690 in Pool acid overnight, and it removes the scale nicely, mayby a bit longer, found this out by trying something else,

Des Horn
03-07-2011, 07:24 AM
I have done many blades in the secondary zone , making sure that the required temperature is not overshot or not reached , and have never had a failure.
At this time the navy is testing blades tempered at this point.
Their specifications for the knife can best be described as a pry bar that can cut.
I worked as close to their design as possible (It did need some serious modification) but the end result is scary strong.
The edge thickness is almost double the normal .6mm but it cuts like a dream chops steel cable up and is still able to cut leather after all this abuse.
The most edge wear (not damage) occurred when chopping stainless cable into short pieces.

HiltonP
03-07-2011, 11:16 AM
Just to back Des up, I've seen his knife cutting pieces out of a steel beam!
It should come with an R18 age restriction!

Des Horn
03-07-2011, 07:48 PM
Hi Neels, just leave the N690 in Pool acid overnight, and it removes the scale nicely, mayby a bit longer, found this out by trying something else,

Hi Chris,
Surely it is easier to use steel with no scale ?
Time is a precious commodity!

Buffalohump
03-09-2011, 10:58 AM
Des, I have been using my Spyderco Stretch in ZDP-189 a lot lately and I havent had any issues with chipping. However, I dont use it hard or abuse it because its a nice knife and now discontinued and I dont want to ruin it. This is a dilemma I have with many of my knives! I like good steel but I am not inclined to push them too hard because they cost too much... : )

As far as S30V goes I have several knives in this steel and only one chipped (thanks to my wife, who claims she has no idea how it happened). I have heard that if one polishes the edge with repeated stropping or buffing it is far less likely to chip. I'm referring to micro chips here. If one uses it as a chisel or screwdriver I'm sure the other kind of chipping will happen regardless!

I know Mart uses his Insingo pretty hard and I dont think he's had any issues with it chipping but I'll let him answer that question.


Hi Marthinus,
So that is why Gareth came to visit last week !
This young man has masses of talent and if he can survive the first few years in the market he is sure to be around for a very long time.
Please post the pics when you get them.
I am convinced that at this time RWL34 is up with the very finest all round knife steels available.
(lets consider NITROBE 77 as still too rare to be put into the mix)
VG10 is a great steel and CPM154 is far superior to 154CM.
I still chuckle over the man from crucibles comment on ZDP189. "It appears to be a type of D2 on steroids" . But recently I have heard complaints of edge chipping.
How would you rate your S30V by Chris , do you "Use but not abuse" your knives?
The question is because a well known friend in the USA has stopped using it as a result of too many complaint as a result of edge failure.
I have some heat treated blanks from him in S30V that I am playing with.
Plan to make myself a carry knife and not abuse it but work it very hard!

mete
03-09-2011, 03:18 PM
Chipping - There is a problem that comes up fairly often on the forums and that is chipping of a new knife . From my knife experience and industrial experience I believe that most of this problem is caused by overheating during factory grinding and polishing. It is very easy to overheat blades especially when grinding thin blades and even more so at the tip. Grinding always creates heat so it's important that you don't create any more heat than necessary. Go slow , cool often.
Initially S30V seemed to have a chipping problem but then makers learned proper HT.
Most chipping now ,of any steel, seems to disappear after 1 to 3 sharpenings.