The test is performed twice. Otherwise, the test results won't be accurate.One method is by using a diamond-tipped cone to forcibly impact the metal. Steel’s hardness is most often altered by the addition of carbon. Initially only a minor load of pressure is applied, and the measurement is taken. The hardness of a steel is determined by the heat treatment of the blade. © Misen, LLC For press and general questions, email us at [email protected] But steel that’s too hard can make a knife blade brittle and lower its tensile strength, so the knife will be easy to damage if misused. Chromium is also the element that makes steel resistant to rust and discoloration. An example is stainless steel AUS-8, which usually 57-59 Rc. The scale is created by comparing resistance to indentation. At the other end of the spectrum, the Vickers hardness test method is used on thin metals, as well as composites and ceramics. The scale that bears his name determines relative hardness of metal by measuring the depth of an indentation after a heavy object impacts a piece of metal. The differential depth hardness measurement was conceived in 1908 by a Viennese professor Paul Ludwik in his book Die Kegelprobe (crudely, "the cone test"). The Rockwell hardness test is the industry standard for knives. So, how do they go about testing metal?First, the metal needs to be heat-treated and perfectly flat. The pressure is dramatically increased for this second test with approximately 300 pounds of pressure bearing down on that diamond tip.The difference between the amount of pressure used for the first test and the second test is the Rockwell hardness number. In fact, if it's really hard, it can shatter just like glass on concrete!The steel used in making a knife also has a great deal to do with how well that knife will hold an edge. The test is performed at least twice on a piece of metal to produce an average. Eventually the test was adapted to test non-metallic materials - even plastics.How is Rockwell hardness measured?The Rockwell scale measures the relative hardness of a metal. Today, we can be far more precise by using methods such as. Manufacturers usually offer a hardness rating range because steel’s hardness will vary slightly. And it’s how we know that the hottest chili pepper in the world — the Carolina Reaper — has a rating of 1,641,183 Scoville units. Because Rockwell testing is done on only a small area of the metal, it's possible that a nearby area could yield slightly different numbers. In simple terms, the higher the number, the harder the steel. The HRC rating is a measure of quality for you, but for knife manufacturers, it’s more of a way to maintain quality control. There are so many types of steel, it can be difficult to determine what the best steel for kitchen knives is — unless you have a system of precise measurements. That’s an important consideration when choosing a, Don’t Let Rockwell Be Your Top Decision-Maker. Rockwell C, 150kg Rockwell B, 100kg Brinell, 3000kg 10mm Ball Vickers Shore Scleroscope … The harder material allows for a thinner blade with a finer cutting edge. Everyone in the steel industry recognizes the Rockwell hardness scale. You probably wouldn’t use a Maserati as your commuter car, just as you wouldn’t want to purchase a high-end Japanese-style chef’s knife with an HRC above 60 for everyday use in your nonprofessional kitchen. A knife made of harder steel will stay sharper longer. The Rockwell hardness scale important to your search for the perfect kitchen knives because harder steel holds its sharp cutting edge better than softer steel. Sign up below to be one of the first to know when Misen knives are back in stock! A kitchen knife with an HRC above 60 rewards you with excellent edge retention, but it will take more time and effort to sharpen when honing no longer restores that razor-sharp edge. A knife that could chop trough bone, hard woods, dig and pry needs to be durable first and foremost. For instance, a harder steel with a RC of 58-62 will hold an edge better than a softer steel. Anything below a 52 HRC rating would be too soft for a kitchen knife. Testers then measure how deep the cone penetrated from a given amount of force. The Rockwell hardness test allows knifemakers to find a balance that promotes blade sharpness and helps the owner keep it that way. The differential-depth method subtracted out the errors associated with the mechanical imperfections of the system, such as backlash and surface imperfections. Each different steel alloy has its own optimum range that balances hardness with performance and the intended use.So, why does a knife's Rockwell rating matter? Be first to receive news about sales, coupons & new promotions. A knife with an HRC in the high 50s offers higher tensile strength, meaning it can flex without breaking. , and each uses a unique combination of test forces and types of indentation. During the first test, only a minor amount of pressure is applied, using a diamond-tipped point on something that looks like a pencil in a drill press. Some steel is actually too soft to make a practical knife. Today, we can be far more precise by using methods such as high-pressure liquid chromatography. Generally, a knife with a Rockwell Hardness Scale rating of 58-62 will hold an edge better than a blade that has a lower HRC rating. The amount of force and depth of the cone-shaped indentation is then measured. Keep HRC in mind, but place more importance on the style of knife you prefer. The scale follows the letters of the alphabet. What is a good rockwell hardness for a knife?The hardness of a knife is very important as far as its performance and durability. It shouldn’t be hard — or difficult — to buy quality kitchen knives. Two (or more) tests on the same piece of metal will produce an average for that particular piece.Why a range of RC numbers? A rating in the low- to mid-50s will mean that the knife blade will not hold its sharp edge as well, but it will be easier to sharpen and require less skill to maintain. The Rockwell system is universally accepted as a hardness baseline. The difference between the depth of the first and second indentation determines the hardness. This ensures that the test area is completely flat and provides a target for the major pressure test. Knife makers heat the metal for their blades to specific temperatures. The scale follows the letters of the alphabet. It’s relative unless we have precise measurements for comparison, which is why, in 1912, Wilber Scoville decided on a scale to rate the pungency of chilies and peppers by measuring their capsaicin content. HRc refers to the Rockwell Scale of Hardness, part C. The Rockwell scale is widely used by metallurgists to define just how hard a piece of steel is: the higher the number, the harder the steel. A particular metal's rating is important to the knife maker because a harder steel will hold an edge better than a softer steel.There are several different Rockwell scales; each one is used for a different material. Getting what you've paid for The Rockwell test helps knifemakers balance the three most important factors that can affect the quality of their finished product: hardness, flexibility, and toughness. Softer steel makes knife maintenance easier. Diamond is the hardest natural substance known to man. Like a fancy sports car, a knife with an HRC rating well above 60 may be expensive and hard to maintain. A rating above this number indicates extreme brittleness. You end up with a Rockwell hardness number value measured at the microscopic level and expressed in degrees. Having these three factors in proper balance allows them to produce a knife that will take a sharp edge and then keep that edge under a range of conditions without damage to the knife.Buy a high quality knife and you'll experience the lasting quality and pleasure of use that comes from a knife with that properly executed balance.Lots of abbreviations, but just one scaleThere are several different abbreviations a knifemaker may use when referring to the scale: HR, HRc, HR C, RC, Rc, C on the Rockwell Scale, Rockwell Hardness C Scale, Rockwell C scale... No matter how it's written about knife steels, they all refer to the same scale (c). However, one steel is not better than another simply because it is harder. Scale C is specifically used for rating the steel used in knives.The highest RC rating is not necessarily the bestA harder steel will generally hold an edge better than a softer steel, but it's also more likely to crack or fail.