Nitrogen Enhanced Knife Steels The Facts

 Nitrogen Enhanced Knife Steels The Facts in a Practical Sense (so far!)

Joe Vogel Evo-X Nitro-X7 Stahl Wanger Linder Kasé Super Edge 7**

HRC 62

                             

A simple but functional well-made synthetic sheath was supplied to house the knife. It is both riveted and stitched and has a rigid plastic liner to prevent the knife damaging the scabbard. The belt loop is also similarly constructed.

It has long been known that the presence of Nitrogen in steels has both beneficial and also undesirable effects. Some of those undesirable effects which might first come to mind are those of actual elemental nitrogen (gas bubbles) forming within finished ingots.

The desirable effects are still being vigorously investigated and much current research is focusing upon what are known as "High-Nitrogen steels*" 

(Ref: The Review article: *Nitrogen Steels and High-Nitrogen Steels: Industrial 2 Technologies and Properties 

Alexandr Svyazhin, Liudmila Kaputkina, Inga Smarygina, and Dmitry Kaputkin

Journal of Steel Research International Wiley-VCH Germany. 2022

I would highly recommend reading the review article cited above for a full overview of what is currently known about the effects of Nitrogen as an alloying component of steels.

However, all of that being said for the above "High Nitrogen steels",  ie steel alloys enhanced with Nitrogen under pressure during the production process, Buderus Edelstahl, a German steel manufacturer has been able to produce a steel alloy with up to 0.2% Nitrogen at atmospheric pressure in the liquid state. This is being achieved via the natural absorption of atmospheric nitrogen during the melting process they use. 

Although the nitrogen content is lower than that when compared to melting techniques which use  greater than atmospheric pressures (Trinks, C. Pers. comm. Buderus Edelstahl 2025). Trinks states that with this process, there is "no risk" of the steel losing any nitrogen because of outgassing during subsequent heat treatment processes (Trinks, C. Pers. Comm. Buderus Edelstahl 2025).

Obtaining the maximal N concentration is highly dependent up the other alloying elements and Buderus have found that Cr content in particular plays a major role.

Is Knife Abuse Normal? and Nitrogen Steels

Kitchen knives are the best examples of knives, which by default, encounter total abuse during their working life, day after day. 

They are used for cutting against all sorts of surfaces with zero consideration for the edge because they are of course a tool and that tool's job is to prepare food whether in some dive of a cafe to a (what some consider) 5 star restaurant. They will be resharpened countless times and definitely not on some 1000 dollar precision knife aficionado's sharpening device. The sharpening tool will probably be a butcher's steel or similar, or maybe at best (for that environment) a set angled grinder that one simply drags the knife through.

Very few knife makers in the kitchen industry are highlighting or even using nitrogen to their advantage, with the major players basically using (what they are all calling "their proprietary steel grades. Let me tell you, most of this is marketing hype, with the major steel alloy in use being Din 1.4116 that is also known as X50CrMoV15. 

Now just to clarify, if this steel is properly heated treated then a good knife blade can be produced just like HC420 can also produce a good knife blade. I have them and will trust my life and those of others around me with such tools. However, if the heat treatments are mediocre then DIN 1.4116 is garbage. No different to even a "high end" knife steel with a poor heat treatment. Heat treatment is science NOT ART!

One knife manufacturer Fox Knives of Italy, their kitchen line "Due Cigni" do in fact manufacture their kitchen knives using a nitrogen enhanced steel alloy. X50CrMoV15N such as this model (which I own and use all the time) features a nitrogen enhanced steel butcher's knife.

Why am I telling you this? Well it might be because the addition of Nitrogen (regardless of the technique) should and it does cause the formation of nitrides. Butcher's knives are probably of the most heavily "abused" forms of cutlery wielded by the human hand. Just think about it. The knife edge may regularly contact bone and or other knife dulling surfaces such as synthetic or natural cutting boards, stainless steel surfaces etc. Durability is key for such a knife edge in an active butcher shop.

So how does this all translate into the outdoor world?

Well if you haven't seen the very thorough testing done by Roman Kase of Kase knives in Switzerland; where he made 3 identical knives with the same heat treatment, one of which was made with Nitro-X7. He demonstrated at the microscopic level that, surprise, surprise, Nitro-X7 out performed the following 3 blade steels:

(Buderus Nitro-X7  (X70CrMoVN15) (Nitrogen 0.15-0.2%) HRC 63.3)

1/ CPM*** MagnaCut (C 1.15%, Cr 10.7%, Mo 2%, Nb 2.00%, V 4%, N 0.2%) HRC 63.5

2/ Böhler M390 (C1.9%, Cr 20% , Mo 1.0%, W 0.6%, V 4.0%) HRC 64.5

3/ Nitro V (X70CrN13) at HRC 62.0

Especially when examining lateral edge stability. Speaking of lateral edge stability if you are familiar with my reviews I often demonstrate the use of a blade by said ways scraping for example to produce extremely fine tinder material from birch bark. If produced in such a way, even the weakest sparks from a steel will ignite such scrapings! During this process, if the knife edge is unstable it will either roll, or chip. Neither of these results are desirable for the longevity of the knife edge, so lateral stability is key to a good outdoor blade if you ask me. 

For those who don't know, the designation "N15" means that the amount of the element "Nitrogen" (that's right, it's a gas) can reach up to 0.15% per volume.

The X__ means 0.5% C for the X50 or X70 means 0.7% carbon content on average for the alloy mix.

Some Brief History

Once Nitrogen was considered disadvantageous to steel alloys however, it has also been known that with careful control it has some very interesting beneficial effects but obviously not alone but in conjunction with other alloying components and the methods of introducing nitrogen to the alloy.

Let's examine this further

WildSteer X50CrMoVN15

As for WildSteer, a French company, they used to rave on about their "nitrogen doped 4116 steel" but now they say nothing on their current marketing literature about such things.  They also used to go on about how they forged some of their knives (now listed as not available). No such ramblings anymore from them! Personally, I'm not jazzed about any of their knives. However, if you are a WildSteer owner/fan and love them, then please let me know why,  with your comments, they will be  most welcome!

FOX (Due Cigni) X50CrMoVN15

Fox knives from Italy, their kitchen line Due Cigni. Personally, I don't see the X50CrMoVN15 any better than the stuff other kitchen knife manufacturers such as DICK, Victorinox etc. are using ; EXCEPT the handles are far better on the Due Cigni line. The Butcher's knife shown below has been hardened to around HRC 58 and is difficult to sharpen if left go blunt and this latter condition is a real possibility in an active kitchen.

NITRO-X7

Now We Have A Truly New Kid On The Block!

There is a new knife steel in the Nitrogen steels and that is Nitro-X7, developed by the German company Buderus Edelstahl in conjunction with Kase Knives of Switzerland as I mentioned above. 

We see this steel being used for the production knives from Dirk Wanger and the knife I have for review is a design based upon the German YouTuber/survivalist/biologist Joe Vogel and Roman Kase of Kase Knives Switzerland.

Wanger Linder X70CrMoVN15

Nitro-X7 has a carbon content of 0.7% and a Nitrogen content of up to 0.15-0.2% according to Buderus Edelstahl.

What sets this Nitrogen enhanced steel apart from other Nitrogen enhanced steels and also those of certain powder metallurgical steels is the incredibly fine microstructure  which is on par with such microstructures observed for PM steels!

 Unfortunately it has not been possible to gain permission to republish the Micrographs seen on Buderus's site regarding Nitro-X7 So please visit their site to check them out. As far as i know there is yet to be any published papers regarding this new knife steel, although i suspect this is not far away due to the significant difference Nitro-X7 has over other popular knife steels.

To be honest I've never watched Mr Vogel's YouTube channel, then why would I, since it is in German and I just passed it at school and I absolutely hate this auto dubbing as it is so super annoyingly irritating to listen to, I'd rather brush up on my German LOL. But seriously, this design looks good for many an outdoor tasks (and it is) from gutting fish to camping and hiking duties, and that's exactly what we put it through.

There is no question about the comfort of this TPE grip. This grip, I do have loads of experience with this style since the days of collaborating with Linder Knives and using the Super Edge series of knives. Then I handled knives completely covered in mud (Super Edge 2) and no problems! See my video here

For a smallish knife the spine is very thick (I measured 4.85mm ie 0.191" thickness)  which is 5mm and reassuring for a light to medium work.

If you are concerned about the thickness of this small knife then rest assured it is more than strong enough for some heavy (but not abusive work). Working carefully we used this same knife to harvest fat wood in the absence of a  folding saw!

You can see the video here of how I obtained this fat wood. 

This knife is perfect for food preparation as the blade is uncoated, so will alleviate anyone's concerns regarding any toxic properties of blade coatings. Personally speaking as a scientist (biologist neuroscientist) I do not believe there is any scientific evidence to prove that blade coatings such as TEFLON is of harmful nature to human beings. Please NOTE, I said "scientific", not unsubstantiated information from the social media of which this abounds  with such BS.

This new model from Wanger Linder can be  housed in a simple but effective synthetic no nonsense scabbard made from ballistic  nylon and a hard polymer insert . It is more than enough for the safe carry of this knife for hunting, fishing, hiking and camping activities.

The same rigid plastic material helps to keep the belt loop open. This scabbard's construction is further enhanced  by being riveted at all potential stress points.

Here's a serious test for the sharpness retention of ANY knife steel. Try cutting the dried stems of the Fairy Ring Champignon mushroom (Marasmius oreades). At best when these tiny delicious mushrooms are fresh, the stems are extremely fibrous (they are usually not eaten) and once they desiccate*** these stems become incredibly tough and if a knife edge is not extremely sharp one will not be able to cut through  them without considerable effort, as these stems become very resistant to cutting. I have to say that after a half a day of cutting through dried mushroom stems with this Nitro-X7 blade was still performing like no tomorrow!

Cutting close to the ground there's always a chance to contact some stones abrasive materials. Simply cutting grass is abrasive as many grasses have an epidermis of cells containing high amounts of silica. So far the Nitro-X7 is holding up  very well and we will continue to use it without retouching the edge at all during the whole duration of testing like all of our other knife tests.

*** one of the few mushrooms which can still be picked when fully desiccated.

Can the blade produce some feathers?

Ok so this is just soft pine, later we will try harder woods.

Cutting close to the ground is no problems with this steel at HRC of 62.

Afternoon out picking field mushrooms!

Seen above taking wild Oyster mushrooms

**Many thanks to: Dirk at Wanger Linder for supplying me with the knife for testing. Also many thanks to  Dr Clemens Trinks (Expert, Product Technology)  Buderus Edelstahl Germany for an insightful correspondence regarding Nitro-X7.