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These are the properties of knife steels that matter most to knife owners and makers. Some Custom knife makers use a dozen different steel alloys to make knives, others only one. Their choice will affect your custom knife for its entire life. So you either trust your knifemaker or question WHY they only use "Steel A" for the knives they make. It's important enough to know that you should ask. The properties of a given knife steel affect how a user or owner of that knife perceives the usability of that given knife. Does it stay sharp for a reasonable time? Does it chip or deform when used? Does it rust when left wet? Check the list of Knife Steel Properties below that control these "usability" features and make your new knife easy to use and maintain! 1 - Knife Steel Hardness Steel hardness is a measure of the strength of your knife or its ability to resist permanent deformation. Most often, knife steels are tested for hardness using the Rockwell C scale. The Rockwell tester works by indenting steel with a fixed load and then measuring the distance the indenter penetrates the steel. This reading then gives the knife maker a quality assurance measurement to be sure the heat treatment protocol for a given knife has been successful. High hardness increases edge retention and reduces toughness, so a "tempering" process is applied after the initial heat treatment to reduce brittleness while maintaining an appropriate hardness for the intended use of the knife. In the past, Rockwell readings of 52-57 were considered adequate for most knives. Many newer steels and even older formulations easily achieve Rockwell 62-65 while maintaining adequate toughness. This alone improves edge retention. 2 - Steel Toughness The toughness of given steel tells us the steel's ability to resist breakage, chipping, fracture, or catastrophic failure. It is typically measured with a Charpy Impact tester. This is a destructive test where a weighted pendulum is dropped into a steel sample of a controlled size. The amount of force required to break the sample is recorded at foot-pounds of torque. The higher the force required to break the sample, the higher the toughness. Tougher steel displays greater resistance against impact, bending, and twisting forces. It can also take a finer edge without the risk of microfractures, to a reasonable extent. One of the Catch-22 scenarios in knife making is this - as hardness increases, toughness decreases. So, it becomes important for the knife maker to find a balance between the two properties that make for a useable knife. "Toughness is a measure of how much resistance a steel has to fracturing. In the context of a knife, this would be chipped edges or broken knives." -Dr Larrin Thomas, Knife Steel Nerds 3 - Edge Retention The quantity and hardness of carbides in the hardened matrix of a steel knife are crucial in determining its wear resistance and edge retention. The iron/carbon phase known as martensite has a maximum theoretical hardness based on carbon content, but it has a limited useable hardness before it becomes too brittle for practical use. Carbides, which are formed when alloying elements are added to the original steel, play a significant role in increasing edge retention and wear resistance. Most alloying elements can join with carbon to create carbides that are considerably harder than the surrounding steel matrix. Chromium carbides, even though they are the softest, are significantly harder than the steel matrix holding them in place. The hardest carbides are Vanadium and Niobium carbides. However, there is a tradeoff with carbides, as with all things knife and steel-related. Carbides in significant volume, especially in large sizes, can make any steel less tough by creating crack initiation points that weaken the steel. Machinists often use carbide cutting tools that are very hard but also very brittle. Therefore, some carbide in knives is good, but not too much. Edge retention refers to the ability of a knife to retain its edge during cutting. Factors controlling edge retention are hardness, toughness, carbide content of the steel, and the edge geometry of the knife. For example, a harder knife will cut longer than a softer knife of a given steel. Tougher steel will resist chipping and micro-fractures that would compromise the edge at the microscopic level. Steels with a higher carbide content typically have better edge retention simply because carbides are harder than the steel matrix surrounding them. Below is a hardness chart of typical carbides that could be present in a given knife steel, provided the element is in the steel. The far right column shows Rockwell C hardness for each. The increased hardness of the carbides provides additional edge retention. Dr Larrin Thomas has done extensive testing around edge retention. His results and analysis are in this article: "Testing The Edge Retention of 48 Knife Steels" 4 - Stain Resistance Stain resistance most often refers to a knife's ability to resist corrosion and oxidation or, more simply, rust. To make a steel stainless, enough Chromium must be added at the foundry so there is "free Chromium" in the matrix that isn't tied up with carbon in carbides. This free Chromium then reacts with Oxygen on the surface of your knife to create a microscopic layer of Chromium Oxide. It is this layer that provides the steel of your knife with stain resistance. Molybdenum and some other elements also contribute to stain resistance. 5 - Sharpenability The term "sharpenability" refers to the ease or difficulty of achieving a proper edge on a knife made from a particular type of steel. This aspect is affected by wear resistance, as sharpening involves removing any material that doesn't contribute to a precise edge. If a knife steel is highly wear-resistant and contains a large amount of hard carbides, it may be difficult to sharpen without the use of diamond stones. On the other hand, simple carbon steels can be sharpened easily but may not have a long edge retention. Knife Steel Properties Matter For The Life Of Your Knife No single steel is perfect for EVERY job a knife might do. Simple carbon steels are easily sharpened and take a keen edge, but without your dedication to proper maintenance, they will turn orange with rust. Knives with extreme edge retention are notoriously difficult to sharpen for you and very difficult for me to make a knife from. Let's have a talk about how you intend to use your knife, your attention to maintenance, your ability to sharpen, and other factors. Then we can choose a knife steel that's right for you! More FREE Learning: What is Heat Treating? The Next Ultimate Knife Buyer's Guide How I Design and Make a Kitchen Knife What Makes a Good Chef's Knife? Knife Safety Tips Order Your Custom Knife from Keith Nix Knives Shop Now! keithnixknives@gmail.com 828-337-7836 Thanks for reading, Keith Keith Nix Knives

Keith Nix Knives FREE Learning!! Which Hunting Knife Style is Right For ME?? Does Anyone Make Hunting Knives Near Me? Everyone who hunts has a unique perspective on what constitutes a good hunting knife. This is partly influenced by the type of game each hunter pursues, and partly by their family traditions. Some prefer large, sturdy knives while others prefer shorter, more precise blades that are agile. For instance, bird hunters require different blades compared to bear, deer or rabbit hunters. Similarly, fishing enthusiasts are also hunters, but their blade requirements are distinct. STEEL Let's talk about the steel that your knife is made from, before we dive into blade shapes. Over the past two decades, the knife market has introduced a number of "super steels". Some of these offer exceptional wear resistance - meaning they hold their edge for a long time - while others provide superior stain resistance. Others still tout advancements in toughness or hardness. Hunting knives are essential tools for any outdoor enthusiast. However, choosing the right steel for your hunting knife can be a daunting task, especially if you're looking for a steel with high wear resistance or edge retention. These types of steel can be incredibly difficult to sharpen in the field, which can be a real problem if your knife becomes dull during a hunt. If you accidentally damage the edge of your "super steel" knife while cleaning game, you may not be able to fix it unless you have a diamond hone with you. This is because these types of steel require a different type of sharpening stone than traditional carbon steel knives. Diamond stones are the preferred choice for sharpening high-performance steel knives, but they can be expensive and difficult to carry with you in the field. Additionally, the cost of producing and using high-performance steel can be significant. For example, imagine a hypothetical steel called CPM-XYZ that has ten times the wear resistance of traditional carbon steel. CPM-XYZ requires diamond stones to sharpen, costs 5-7 times more than traditional steel, and incurs higher production costs. This means that knives made with this type of steel will be more expensive to purchase and produce, and they may not be worth the added cost for some hunters. Ultimately, it's up to you to decide whether the benefits of high-performance steel are worth the added cost and potential difficulty in sharpening. While high-performance steel can offer significant advantages for certain applications, it may not be necessary for all hunters. It's important to consider your specific needs and preferences when choosing a hunting knife, and to make an informed decision based on your individual situation. A hunting knife is a tool, in fact, a multi-tool. Typical classic designs try to make the hunting knife a tool to gut and clean a carcass, skin it, break it down into primal cuts, debone the primal cuts, and fillet a few trout for dinner after the same knife is used to process enough firewood to last all night. Of course, no knife will do ALL that well, and it makes no sense to even try to make one. THE LAUTNER If you're in the market for a hunting knife with a classic aesthetic, then look no further than "The Lautner". The knife is designed to be thin enough to serve its intended purpose as a knife, rather than a small axe-like object for splitting firewood. The drop point measures between 4 and 4.5 inches, providing ample blade length for various hunting needs. The handle is ergonomically designed to fit comfortably in your hand and provide you with maximum grip. I've named this knife "The Lautner", and it is available in any steel that I currently stock. Whether you're an avid hunter or simply appreciate the aesthetic of a well-made knife, "The Lautner" is sure to impress. THE ROLLINS If you prefer a smaller hunting knife, I can offer you something different than the standard ones. It is a smaller, more agile blade that was commissioned by a friend of mine. We worked together to design it, and named it "The Rollins Pig Skinner". This knife has a 3" blade, which is perfect for skinning feral hogs that my friend hunts in South Carolina. The blade length can be increased to around 4" to suit your preferences. The co-designer of this knife is my friend, and we named this blade "The Rollins" after him. The knife is made of high-quality materials and is perfect for hunting, camping, and other outdoor activities. Its smaller size makes it easy to carry around, and its agility ensures precision while using it. THE DAVIS I also offer you a third hunting knife that may be perfect for your next hunting trip. This knife is designed to excel in two different tasks: filleting and skinning. With a 5-inch blade, this knife will easily fillet fish and skin small game. However, if you need to tackle larger animals, this knife can be stretched up to 6.5 - 7 inches to become a boning knife that is perfect for bigger game. This knife was designed in collaboration with a hunting enthusiast who had a particular love for an old fillet knife that was perfect for him to skin deer. The blade is thin and flexible, just like a fillet knife, but still has enough weight to efficiently skin larger game. The best part? This blade can be easily modified to fit your specific hunting needs. Whether you need to skin a deer, fillet a fish, or bone a larger animal, this knife can be customized to fit the task at hand. And it's great in the camp kitchen, performing the duties of a chef's knife. In my opinion, a "hunting knife" should be a "Hunting Set" that includes three or four specialized knives to handle all the necessary tasks from field to table. If you require a specialized hunting knife unlike any of those above, let's discuss your needs and customize a knife that is perfect for you! More Free Learning: The Great Steel Debate Order Your Custom Knife from Keith Nix Knives Shop Now! keithnixknives@gmail.com 828-337-7836 Thanks for reading, Keith Keith Nix Knives

Let's Explore How To Prevent It Happening WHAT'S UP WITH FACTORY EDGES? Knife enthusiasts know that most factory knife edges are not as sharp and durable as those created by a skilled sharpener. Therefore, many knife owners prefer to sharpen their new knives immediately, with some suggesting that multiple sharpenings are needed to assess a factory knife's performance accurately. But why is this necessary? And do power grinders damage knife edges? The BESS sharpness scale addresses this factory "dullness," noting that typical NEW high-end kitchen cutlery tests out on the Edge On UP! sharpness tester at 250-350 grams of force to cut the calibrated test media, while a kitchen knife done by a proficient sharpener can easily be in the 150-175 gram range. It is essential to remember that knives produced in factories may have uneven edges due to the grinding process. The process usually involves rapidly moving belt grinders or wheels and may sometimes be done by hand. This can lead to discrepancies in the edge angle of up to ten degrees in bevels between the two sides of the edge and seven degrees from the heel to the tip. However, this information is not the primary focus of today's discussion. Instead, we will discuss the potential harm that may arise from power grinding the apex or edge of a knife. By understanding the risks involved, we can take steps to ensure that we are using our knives safely and efficiently. HOW HEAT AFFECTS THE EDGE OF A FINE KNIFE Grinding steel with abrasive wheels or a belt grinder generates heat due to the friction between the abrasives and the steel. The heat created during this process can be a genuine concern if it exceeds the original tempering temperature of the steel. If this happens, the knife's apex could become over-tempered, causing the steel to become softer. This can have a negative impact on the durability and performance of the knife. The tempering temperature of the steel is a critical factor in determining its hardness and toughness. When the steel is heated to a specific temperature and then cooled, it undergoes a transformation that changes its properties. If the heat generated during grinding exceeds this temperature, it can undo the tempering process and cause the steel to become softer. Furthermore, if the heat generated during grinding is allowed to continue increasing, it can cause the edge to re-harden and become untempered martensite again. This phase of steel is very hard but also very brittle. This can further compromise the overall quality of the knife by making the apex brittle and prone to chipping or breaking. Therefore, it's crucial to approach knife grinding with great care and precision to ensure the best possible outcome. Remember that the apex of a knife is very thin, and heat build-up can be rapid and often catastrophic if not managed properly. Proper cooling and frequent checks of the temperature of the steel during grinding are essential to avoid over-tempering or re-hardening of the edge. By taking these precautions, you can ensure that your knife will maintain its durability and performance for a long time. When grinding the blade of a knife, a moderate amount of heat is acceptable in the thicker regions, like toward the spine. This is because the steel volume of the blade functions as a heat sink and assists in the distribution of heat before higher temperatures can damage the blade. However, the scenario is different for the microscopically thin edge of the blade. A well-honed kitchen knife generally has an edge width of a half micron or less. (A micron is about .00004") This size is so minute that it can only be observed clearly with a scanning electron microscope. This minuscule area is of utmost importance and is highly susceptible to damage caused by heat. It is, after all, the BUSINESS part of the knife. Do power grinders harm knife edges? Making knives requires the steel to be heated to high temperatures, quenched quickly, or cooled down to room temperature, and then tempered at a lower temperature to reduce internal stresses. The typical tempering temperature is around 400°F (200°C ) or less. If a knife being sharpened is heated to a temperature lower than that tempering threshold, it's unlikely to cause any damage at all. However, the temperature can easily exceed that limit in the sub-micron area of the edge's apex within a second or less, resulting in a compromised "heat-affected zone." In this zone, grain structure, hardness, and temper will likely be affected. Edge stability and edge retention will be adversely affected. The heat-affected zone (HAZ) is an area of the knife edge that has not been melted but has undergone changes in properties due to exposure to relatively high temperatures. The HAZ is located from the apex back through the blade to the unaffected base material. This HAZ may be only a couple of thousandths of an inch back from the apex, but if it is there, your edge is degraded. Tempering color or "heat tint" is a useless barometer for checking for HAZ. If you're grinding fast and dry, HAZ cannot be avoided. Your knife won't hold an edge as well as it SHOULD. So, is it best to avoid the situation altogether? I believe it is, and there are ways to mitigate the creation of this heat-affected zone (HAZ). Let's go over a few: 1) Only Hand Sharpen Knives-- This isn't a viable option for professional knife makers and sharpeners. Still, it could be the answer for the home sharpener who only wants to keep personal knives keen and ready. Hand-sharpened edges haven't been exposed to the potential heat caused by grinding with belts or wheels. 2) Grind wet-- Add some water or a Kool Mist to your setup. It's messy, but it saves edges! Some sharpening machines come ready for wet grinding as well. Make sure your abrasive belts are the "wet/dry" variety. A belt not rated for wet use will disintegrate rapidly. 3) Grind Slowly-- Slow down the speed of your machine. A powered knife grinder, whether using belts or wheels, should be a variable-speed grinder. Does your machine have only one speed? Then don't grind knives on it. You cannot control the heat. If you're ruining your customers' knives or even your own, why are you doing that? Light pressure and quick passes can't stop the edge, the APEX, from being overheated. 4) Use Structured Abrasives-- Structured abrasive belts such as 3M Trizact generate far less heat than other types of belts while still moving material at an acceptable rate. 5) Dip The Blade-- Dipping the blade in cold water after each pass on your grinder will help prevent the build-up of excessive heat, but it WILL NOT save the apex of the edge. That heat and over-tempering does happen in milliseconds. 6) Hand Sharpen After Belt Grinding-- I do this for every knife I sharpen. ALL knives get sharpened by hand after a touch-up, edge thinning, or reprofile on the belt sander. This helps remove the possibility of HAZ. At Keith Nix Knives, we use all the other precautions when belt sharpening, thinning edges, or repairing chips, cracks, or broken tips. Then, as an added precaution, all finish work, or the final sharpening, is done by hand. Hand sharpening knives ensures we deliver the finest edges while minimizing the chance for a HAZ (heat-affected zone) that may ruin your blades. (Here is How your knives will be hand sharpened at Keith Nix Knives.) SUMMARY: The Question is: DO KNIFE GRINDERS DAMAGE EDGES? The extremely small volume of material at the apex of a knife can be easily overheated to the point of overtempering. The knife sharpener needs to realize this and plan for it. It is common for knife edges to overheat during power sharpening operations, as the small volume of steel at the blade's apex makes it prone to this issue. To minimize the chance of overheating, it is advisable to grind wet, grind slowly, use structured abrasives, and dip the blade in water. Hand sharpening ONLY is an effective way to eliminate or minimize this issue. Hand sharpening a small micro-bevel after grinding can also help. Exercising great care while sharpening a fine knife is essential, as it can be ruined in mere seconds if not appropriately handled. As always, I'm grateful to the Knife Steel Nerd in charge, Dr. Larrin Thomas. I reference his article and study for much of this. If this subject interests you, I suggest you read Dr. Thomas' article. It can be found here: "Does Sharpening With A Grinder Ruin Your Edge?" -By Dr. Larrin Thomas Other sharpening posts and articles at Keith Nix Knives: Local Knife Sharpening in Black Mountain How I Sharpen Knives Quantifying Sharpness Order Your Custom Knife From the Keith Nix Knives Shop! Sign Up For The Keith Nix Knives Newsletter! Click HERE! keithnixknives@gmail.com 828-337-7836 Thanks for reading, Keith Keith Nix Knives

Why Use Liquid Nitrogen? What Is Liquid Nitrogen? What Does It Do? How Do You Know It Does That? Will LN2 Fix a Bad Heat Treatment? People ask questions! And we're going to try and provide some answers today about one of the most misunderstood parts of heat treating knives- the cryogenic quench! WHAT IS LIQUID NITROGEN? The air we breathe is 78% gaseous nitrogen. It is all around us as you read this. So there's plenty of this element, but we need it to be liquid, and we need it in a container! This involves a process called "air liquification", which compresses and chills air or gaseous elements to the point where its constituent components separate and liquify. (carbon dioxide solidifies at -120F, nitrogen liquefies at -320F, oxygen at -297F, hydrogen at -423F). Knowing that, the liquifier can collect each liquified gas at a specific temperature, pretty much in its pure state. Much like a liquor still purifies and collects alcohol, except the temperatures are reversed! Then all that's necessary is to keep it cold, and pump it into my dewar. The vacuum insulated dewar I own insulates so well I only fill it about twice a year! Now remember, LN2 boils at -320F, so I think that's amazing! Why Use Liquid Nitrogen?- When a knife steel is heated to a certain point it changes to a softer, nonmagnetic phase called austenite. That "certain point" is modified by the carbon and other alloying content of the steel. Then as we quench the blade back to room temperature, it will pass a point called Ms "martensite start" , where the austenite begins to convert to the harder, stronger martensite(we want this conversion!). As the steel continues to cool is passes a point called Mf "martensite finish". Now, due to carbon content and other alloying, that Mf temperature can be below room temperature, below freezing, and sometimes even below dry ice temp.(dry ice, or solid CO2 is at least -120F). This can leave a percentage of the matrix as "retained austenite", which isn't a good thing for a variety of reasons. It is critical that the knife go straight from room temp to LN2. A delay of even a few minutes, or the sometimes recommended "snap temper" before LN2 offers an opportunity for the retained austenite to stabilize. Don't even check hardness, get your blade in the LN2 now! What Does LN2 Do?- This is the reason LN2 is the choice for cryo treating to insure Mf. It is cold enough to facilitate the conversion of retained austenite(RA) to hard martensite. There are reasons we want to convert this RA as soon as possible. Here are a few: 1) Retained Austenite makes the matrix of the steel softer. At levels around 20% or above, RA negatively affects the bulk hardness of the blade, hindering performance and sharpenability. 2) Under certain stresses, RA can spontaneously convert to untempered martensite. There is a valid reason we temper our knives after hardening. Untempered martensite is extremely brittle and prone to fracture. It has very low toughness. It is prone to chipping. It creates crack initiation points and stress risers. BAD JUJU! 3) RA negatively affects edge retention and sharpenability. Softer steels are harder to properly sharpen than harder ones. Soft steel doesn't want to take a crisp edge, doesn't want to let go of the burr or foil edge when stropping. And then the softer high RA knife gets dull many times faster. How Do You Know LN2 Does That?- There are a number of ways to accurately measure the effects of LN2 on steel. 1) Rockwell Hardness Tester. Running sample coupons before and after LN2, before and after LN2 AND tempering, and at different temperatures, and checking the hardness of each one is a knifemaker's way of verifying our processes are giving the results we expect! 2) Magnetic Resonance Since RA is nonmagnetic, a very accurate measurement can be made of how much RA is in a given piece of steel. While I do not have the means to conduct this test, there is plenty of research available to verify the theory. To the left here is a chart created by Dr Larrin Thomas, showing the effects of austenitizing temperature (hardening temp) and room temp quench vs home freezer vs LN2. It is easy to see that LN2 treated samples are 3.5 Rc points harder compared to room temperature, and 2.5 points harder compared to a home freezer treatment. That's quite a difference, and exactly why I use LN2 treatment on all knives at Keith Nix Knives. Will LN2 Fix A Bad Heat Treatment? - No, LN2 will NOT fix a bad heat treatment. If a custom knife is austenitized at too low a temp, it won't fully harden. LN2 cannot fix that. If the knife is austenitized at too high a temp, awful things can happen like explosive grain growth, too much carbon in solution, and so much excess RA even LN2 can't save the piece. So LN2 isn't a "fix" for anything. It is a logical continuation of a proper heat treatment, that can enhance desirable properties of the blade. Learn more about heat treating HERE! My desire is to make the very best knives I am capable of making. To get the geometry right for the knife and the tasks it will perform. The best support for that geometry is a hard steel matrix that supports the carbide structure of the steel, resists edge rolling and chipping, and sharpens easily. LN2 helps steels achieve all those properties. (Special Thanks to Dr Larrin Thomas of Knife Steel Nerds for his seemingly unending research and generous sharing of his findings with the knife making community.) More FREE Learning: What is Heat Treating? The Next Ultimate Knife Buyer's Guide How I Design and Make a Kitchen Knife What Makes a Good Chef's Knife? Knife Safety Tips Order Your Custom Knife from Keith Nix Knives Shop Now! keithnixknives@gmail.com 828-337-7836 Thanks for reading, Keith Keith Nix Knives