When choosing steel, properties such as sharpness durability, ease of maintenance and sharpening, and last but not least, price and steel availability are considered. All these practical properties are inseparably linked to the hardness of the steel. For Øyo, good steel quality is about finding the balance between the durability of the knife's sharpness, i.e., how long it lasts before becoming dull, and how easy it is to sharpen again. Therefore, we have chosen a hardness level for a large portion of our knives that we believe is right in relation to the mentioned balance.
The Rockwell scale (HRC) provides an objective quality measure that describes the hardness of the steel. The harder the steel, the more material strength. Rockwell is an international hardness scale that indicates the surface hardness of the metal. There are several scales A, B, C, D, E, F, G, H, K, N, and T. The most commonly used scales are B and C, referred to as HRB and HRC, respectively. The scale used to measure the material strength in knives is HRC.
The quality of the knife steel helps determine how hard the steel can be hardened and, in turn, what HRC one can achieve. Different hardening processes will, therefore, give the knife steel slightly different qualities.
There are several variables that can change this relationship. One is the alloy itself, and other factors include whether the knife is forged or stamped. A forged knife will have a relatively greater material strength at lower HRC values. This means that Rockwell must be considered in relation to steel quality, alloy, and whether the knife is forged or stamped.
Knife steel that is hardened beyond 57-58 HRC can result in the material becoming brittle. When the thin knife edge of 20-30 microns, which is common for most steel knives, it is important to have the right hardening. Softer steel may cause it to bend, and harder steel may cause it to break. The material that has bent can be straightened with a honing rod, while with broken material, enough material must be removed so that the edge becomes 20-30 microns again. This process usually involves grinding or the use of coarse honing rods or diamond honing rods. It leads to grinding marks and a less sharp edge.
To make it easier for you to assess the steel quality of an Øyo knife, we have chosen to categorize our knives into 3 different steel categories: Standard Steel, Premium Steel, and Exclusive Steel. All knives will be marked with the category to which the specific product belongs, making it easier for you to make an informed choice.
For us, quality is important regardless of price, but the steel will vary significantly from standard steel quality to exclusive steel quality. Standard steel has a softer steel and requires frequent sharpening to keep the edge sharp. In return, the edge will be very easy to sharpen. Øyo knives in the standard steel category will have a sharpening angle of 20 degrees, and the steel is hardened to approximately 52-55 HRC. Steel qualities falling under this category include, for example, 3cr, 420 steel.
Here you get a lot of steel for your money, making it an excellent choice for most users. The steel is soft enough for you to sharpen the edge yourself but hard enough that you don't need to do it too often (depending on how much you use the knife, of course). The edge is set at 20 degrees, and the steel is hardened to approximately 55-57 HRC. Steel qualities that fall under this category include, for example, 5-8cr, 4116, 440A/B, AUS6-8, 13C26.
Here you get steel quality that truly performs. For kitchen knives, you get a much thinner edge that makes cooking a breeze. In the outdoors, you get full-tang knives with extremely good durability. In the kitchen, the edge is set at 16 degrees, and Damascus knives have a hard core and softer steel in layers on the outside. Again, this steel quality is not suitable for hard (e.g., bone) or frozen foods but exceptional for soft foods. The edge may be somewhat more challenging to sharpen yourself, but in return, you have a sharp edge for a very long time. The steel is hardened to approximately 58-62 HRC. Steel qualities that fall under this category include, for example, 9cr, 440C, AUS10, 14C28, VG10. We can help you sharpen your knife in Geilo or at Gokniven with Asbjørn in Skedsmokorset.