Decisions- Familiar Stainless Or The Dark Horse Carbon

 

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By: Chris Wiehle / Property of Cardinal Knife Co.

There are many attributes that qualify a “good” knife – including but not limited to; overall ergonomics, execution of the grind, heat treatment, to the proper choice of steel for the task at hand.  Of these, the one that confuses people most is steel selection, which for now can be broken down into two categories; carbon steel and stainless steel.  Within those two are a plethora of sub steels containing different amounts of alloying elements tailored to the end user’s needs.  The mixture of these elements affect hardness, strength (resistance to deformation under load), toughness (resistance to being fractured on impact), corrosion resistance (rust/staining), and abrasion resistance (edge retention).  The most influential element and the only one we will discuss here is Chromium (Cr).  Chromium is present all around us but when introduced to steel in amounts of at least 10.5% -12% it provides us with what we know as stainless steel.  Chromium also makes the steel stronger and is responsible for the formation of chromium carbides that provide stainless with excellent wear resistance.  Sounds great right? Not so fast; when nature giveth, nature taketh away.  The strength gains come at the cost of lost toughness, and the superior abrasion resistance (edge retention) comes at the cost of being a bit more difficult to sharpen.  So, following those examples, carbon is traditionally tougher, and easier to sharpen, but will oxidize (rust/stain) if left uncared for.  The blade will usually acquire a patina with age acquiring a grayish appearance which also lends a small level of protection against oxidation.  Important note- even stainless will oxidize given time and opportunity. So how does the knife buyer decide?  Continue reading, but keep in mind, the information provided has been “boiled down” and generalized.  We can’t nearly cover specifics and all the steels in use, but hopefully we can provide a firm footing so you will at least know the correct questions to ask.

  1. What do I need this knife for?
  2. Will it be regularly exposed to saltwater or damp/wet environments?
  3. Am I willing to wipe it dry when it’s wet and oil it once in a while?
  4. Is ease of sharpening important to me?

For example – A seafaring fisherman who exposes his knife to saltwater on a daily basis may opt for a stainless blade due to its paramount corrosion resistance.  He may also appreciate the abrasion resistance that stainless offers, which will reduce his time trying to sharpen the blade on an ever moving deck.  An outdoorsman in a drier climate on the other hand may prefer a carbon blade with an easy to sharpen razor like edge for dressing game.   In survival situations you may call on its brute toughness to split firewood, chop through bone, and use with a flint.  If you’re contemplating the big stuff like large “working” knives, machetes, choppers and swords, there’s usually little debate, and the toughness provided through carbon steel is almost mandatory.

stainless_steel_nyt_1-31-1915Stainless steel has been around since the early 1900’s.  It’s popularity skyrocketed mostly because people are lazy and don’t want to care for carbon knives.  The housewives of the time quickly acquired an appreciation for this new cutlery that basically took care of itself.   After that it was only a matter of time until the outdoor market followed suit.  This characteristic is also the main reason stainless knives litter the outdoors dept. of the big box stores.  Not because stainless outperforms carbon, but because it is easier to sell.  Stainless offers many fine qualities, and as a knife maker I use and appreciate both steels.  Carbon however, being the underdog in today’s modern societies, tends to draw my sympathy, so I will close on its behalf.

Your requirements may dictate the need for stainless, or you may simply not want to deal with the care a carbon knife requires.  However, if after reading this you’re still left undecided let me at least remind you of some significant roles carbon steel has played throughout history when all they had was carbon steel.  A time when survival took precedence over anything in regards to edged weaponry.  In its early years the Katana helped the Japanese defeat invading Mongols, it defined heroes in our world wars under the brand name KA-BAR, and legends were made through it on Texas sandbars spawning the birth of the world renowned Bowie knife, in its humblest of forms it continues to prepare the world’s finest cuisines.

6678 E Weld Park Rd / Stillman Valley / IL  61084      815-761-7217    www.cardinalknife.com


Knife Making Is An Illness – Literally

It’s been a while since I got in touch with my huge fan base so I figured I should shoot out a quick update.  In my last post I talked about a bad reaction I had to bird dust or carbon monoxide fumes while forging in my chicken coupe that left me sick for weeks.  Just recently I was hit with another episode lasting about 6 days after inhaling a collection of steel, wood, and synthetic dust from my vacuum collector bag .  The wife said I had the flu, but I know better, so I hit WebMD and down the rabbit hole I went.

Search Query: Can allergic reaction cause flu like symptoms?  Answer: Allergic alveolitis (allergic inflammation of the alveoli producing flu-like symptoms).  Both correct, damn.

All kidding aside, I don’t know what I had, but I do know the reactions are escalating, and it takes less and less exposure the older I get.  So, consider this a warning to any of you that have sinus issues.  There are these things called sensitizers found in wood, chemicals and other materials that classify like this – a substance with the potential to act, through whatever mechanism, to create a situation of airway hypersensitivity where none previously existed.  To compound on this, as the allergy develops, the response becomes more severe with subsequent exposures.

Even if you do not have a reaction to something the first few times you use it, it’s still vital that you take precautions and avoid as much exposure as possible.   I prefer to not be breathing from an air tank in 10 years so I will be investing in one of these bad boys maskcapture.  Take it from these Dead Romans , if it’s foreign to your body, then most likely your body will not know how to deal with it.

 

 


Smithy Update

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That which does not kill you makes you stronger. So they say.

I have completed the installation of a gleaming new roof on my smithy, aka “the chicken coop”. The following weekend I rewarded myself by spending and hour in the coop hand forging my first blade blank. The blank turned out okay (I’ll post that when completed), but I, on the other hand, have been ill for four days following my time spent there. I blamed my illness first on carbon monoxide fumes from the propane forge, but after some research I concluded my symptoms didn’t match those of CO poisoning, but, in fact, pointed to a severe allergic reaction to bird dust, and probably chicken shit as well. I presume, as an added bonus, the heat and stirring exhaust fumes from the forge acted as a catalyst to kick everything into high gear.
Apparently, aviary houses such as chicken coops contain severely allergic levels of bird dust from feathers and feces contributing to diseases such as Histoplasmosis, Bird Breeders Lung, among others, which pleasantly read…”Prolonged exposure to bird dust or other organic particles can lead to permanent damage and disability. For example, pulmonary fibrosis, which is a scarring of lung tissue, can be caused by repeated bouts of hypersensitivity pneumonitis.” (http://www.multiscope.com/hotspot/bird_breeders_lung.htm).

Scary stuff indeed. For now, I guess I’m relocating to another barn.

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Smithy in progress

IMG_20151227_080426282_HDRAfter years of procrastination and indecision I have finally begun work on my blacksmith shop aka “the old chicken coupe”.  The roof, as you can see, needs some TLC, so the tear off has begun and the new tin should be arriving shortly.   I’m in possession of a 110 lb drop forged turkish anvil (pics to come), and am awaiting the pickup of a newly built Atlas propane forge.   We are also trying to finish a basement bath so patience must be exhibited on my part, as I’m pretty excited to get hammering, but family projects first if we want to keep the wife happy :).  I’ll post an update soon.  ~Chris


Sharpening Stainless- Why is it more work?

Carbon Steel French Sabatier Chef Knife

Carbon Steel French Sabatier Chef Knife

You’ve seen the old carbon steel chefs knives, the ones stained with black spots, and washed grey with age.  Have you ever wondered why you still see them being used when there is a seemingly endless selection of new shiny stainless options available?  If you’re someone that uses edged metals often you probably already know the answer.  Many chefs, barbers, and wood workers often opt out of the trendy stainless for the old standby – carbon steel.

What’s the attraction?  Why would someone prefer one over the other.  Most often it becomes a choice of maintenance.  Carbon steel will take a keener edge than stainless, and you will be able to acquire that edge in a much quicker fashion.  Here is a photo taken with an SEM (Scanning Electron Microscope) that shows an ultra close up view of a commonly used stainless blade steel manufactured by Sandvik.stainless carbides sandvik12c27  The stuff that looks like moon debris going across center is actually chromium carbides protruding from the surfaced edge of the steel.  These large carbides contribute to the wear resistance of the steel but, at the same time, they also reduce the toughness and the sharpness potential of the blade.  The large carbides make the knife very difficult to sharpen and tend to fall or be ripped out of the cutting edge during use and sharpening.  As a result, most knife blades made from common stainless steels become micro-serrated making it very difficult to acquire an edge that can match that of a carbon steel knife.  (Photo courtesy Sandvik Materials)

These carbides are extremely hard.  Knife hardness is rated using a Rockwell tester on the C scale.  For arguments sake let’s say you have a Wusthof chef knife with a Rockwell of 58rc.  Those carbides you see in that photo, which are essentially what you are trying to sharpen, may actually test up to a hardness of 70rc.  Most knives, carbon or stainless, average around 56-60rc, so you can imagine why 10rc points adds a new level of difficulty when sharpening stainless steels.

Diamond Stones

Diamond Stones

Many stainless users attack this problem with diamond stones.   Yes, there is actually real diamond grit on the face of these plates, which is one of the reasons they are so expensive.  However, a problem still exists.  If one is not patient during the sharpening process, and simply pushes down harder to expedite the process, the diamond grit will rip the carbides right off the edge of the blade, creating that “toothy edge” and an even longer sharpening process.

So that leads us to the next question- Why then would someone prefer stainless over carbon.  The most obvious reason is corrosion (rust) resistance. The other main one is abrasion resistance.  Those carbides protect the surrounding softer metal and provide an improved wear resistance essentially creating an edge that will last longer.

Carbide analogy

Carbide analogy

Read this Bladeforums post to the left put up by a moderator there who operates under the username “Knarfang”.  He explains it much better than I, and provides a good analogy for carbides and wear resistance.

 

In the end it is completely up to the user and their intentions with their blade.  If you cut carpet all day and need a high abrasion resistance, stainless would be the best choice.  If you are slicing sashimi and tomatoes that requires a refined edge it would have to be carbon steel.

Next post should hopefully include some testing and comparisons between stainless and carbon.  In the meantime don’t buy any knives (or swords for that matter) off the home shopping network.  Thanks for reading- chris

Use of material on this page is forbidden without consent of Cardinal Knife Co.

 


Blade metals II – The Elements

Table of Contents:

  1. Intro
  2. Why you need to know
  3. What is Steel
    1. What is carbon steel
    2. Affects of Carbon
    3. Carbon Steel Review
  4. What is Stainless Steel
    1. Stainless additives (alloying elements) and their affects
    2. Stainless Review

1.  Intro-  In blade metals #1 we discussed the comparative “real world” properties of carbon steel to stainless steel.  For this second installment we will be looking into the metals on a more atomic level, and lightly covering what causes these metals to be different from each other, and how those differences affect their usage as knife steels.   Keep in mind we are only scratching the surface of metallurgy. Furthermore,  we will do our best to keep the text strictly pertaining to knife metals.

2.  Why do we need to know about this stuff?  At some point in our lives we all want to learn more about the things that interest us, and we discover rather quickly that we in fact knew a lot less than we thought we did.  “the more you learn the less you come to know” type of thing.  If knives interest us we owe it to ourselves and the knife industry to have a basic understanding of what makes them tick.  You will thank yourself in the end having purchased tools that best fit your needs.  The following is a simplified introduction to carbon and stainless knife steel.

3.  Steel-

steel make

(courtesy http://www.keenovens.com)

3.1  Adding carbon to iron allows us to harden the resulting steel, so that we may manipulate the steel into useable tools such as knives.  Other common alloying elements include manganese, nickel, chromium, molybdenum, vanadium, silicon, and boron.  Each element adds it’s own characteristics like toughness, hardenability, wear resistance, corrosion resistance and so forth.

Adding each of these elements to iron will result in a different recipe.  There is always a trade off though.  Too much of any one ingredient affects the entire recipe.  Too much carbon (usually over 2%) makes the steel less ductile (more brittle).

Knife steels, to be good performing for your needs, need to fall into a certain “recipe” range.    It would be a poor choice to choose a 1050 medium carbon steel for a small everyday chore knife because you would be sharpening it all the time.  This does not make 1050 a poor steel, it simply means it would be better suited to heavy duty chopping work as an axe.

3.2  Affects of Carbon-  This is only small sampling of available carbon steels.

1095-  The 10xx series of steels are considered simple carbon steels.  Simple because they only consist of a few alloying elements; manganese, phosphorous, and sulfur.  The last two digits, “95” in this case, denotes the carbon content.  For example, here is the AISI (American iron and steel institute) property chart for 1075. 1075 Capture (courtesy http://www.azom.com)

You will see iron makes up 98% with carbon contributing only .75 percent or (75 points).  This represents of very small precentage, but is critical to the hardenability of the steel.  The higher the carbon content the more brittle the steel becomes when hardened.  Less carbon content and you lose edge holding capabilities.  1095 is usually used for knives whereas the lower numbers like 1050 are used in larger blades like swords.

3.3  Review: Like most things, everything comes at a cost.  Generally, as hardness increases, toughness decreases.  Often the lower the carbon, the higher the toughness.  Toughness on the other hand is the maximum amount of energy a material can absorb before fracturing, it can also be thought of as the opposite of brittleness.

4. Stainless steel- Chromium content dictates whether a steel is classified as stainless or not.  Knife steels generally have around 13-15% cr.   Any amount under 13% usually triggers debates of the steels validity in the stainless family.   ASM (American Society for Metals) says “STAINLESS STEELS are iron-base alloys that contain a minimum of about 12% Cr, the amount needed to prevent the formation of rust
in unpolluted atmospheres (hence the designation stainless).” (Courtesy of http://www.asminternational.org/documents/10192/1849770/06940G_Chapter_1.pdf).

Generally, as chromium increases it will contain more chromium carbides, which tend to make sharpening these blades more difficult.  Some stainless steels may have many elements added to boost performance or alter its characteristics. (see below)

4.1  Alloying elements of stainless steel-

sandvik elementsCapture

(courtesy of http://www.smt.sandvik.com/en/products/strip-steel/strip-products/knife-steel/knife-steel-knowledge/important-factors/chemical-composition/)

4.2 Review:  As with carbon steel- the Carbon element also plays a very important role in stainless steel, but as seen above, a multitude of other alloys are used to alter the final characteristics, to best fit the needs of each maker and user.

Once we move past these basic concepts we get into the more involved specifics like; solutions of steel, phases of steel (ferrite, austenite, martensite, pearlite…), heat treatments, time temp transformation curves, quench mediums and so forth.  I will not be covering any of that until I feel confident enough in my knowledge to explain it.

Property of Cardinal Knife 

 

 


Why everyone needs fixed blade..

I wouldn’t say I dislike folding knives, I just don’t love them as I do my fixed blades, and as much as I prefer a nice fixed blade, I still choose to carry a folder as my EDC (everyday carry) knife. They’re more compact and usually suit my daily cutting requirements.  This makes for quite the paradox, that I don’t love to carry what I love to make.  There are days however I would not be caught dead without a trusty fixed blade on my side; a few examples -hunting, camping, hiking, or work around the farm.  There’s certain tasks simply better fitted to fixed blade knives; dressing game, hard cutting, bushcraft and so on.  Fixed blades are stronger, more reliable, quicker retrieval for defensive needs or repeat tasks, and better looking 😉

I realize I am insulting a very large crowd so let me be the first to say how much I appreciate my folding pocket knife.  It serves its purpose quite well, hidden away at the ready for my daily needs of opening boxes and such. Would I choose to carry it hunting? Absolutely not, the potential for bad things to happen is much greater than with a fixed blade.  There are small parts that can break, freeze, or get jammed.  The hinge area creates a weak spot susceptible to bending or breaking.  Especially during survival mode when knives are introduced to circumstances they normally wouldn’t.  Save for last- fumbling around for it in my pocket with gloved hands presents it’s own level of difficulty.  I think of my folding knife comparable to my local Starbucks worker.  I appreciate them both very much.  Both of them perform good light duty work,  both are probably best left to a clean indoor environment, and I’m pretty sure neither of them are good at chopping wood.

My point is this, everyone should have a good fixed blade knife whether you choose to carry it everyday or not. One day your life may depend on the knife you carry.  Choose wisely and live to talk about it!