To measure the hardness of materials, we use the Rockwell scale, which specifically measures the hardness of steel. It belongs among static tests and is in accordance with the standard STN EN ISO 6508-1. Knowing the hardness of our knife is very important, because hard steel is difficult to sharpen, but stays sharp for a long time. On the other hand, soft steel is easy to sharpen, but also blunts quickly.
How the Rockwell test works
The HRC scale serves as a tool for determining the hardness of materials. These materials are tested under load using a diamond with a weight of 150kg (1500N). This means that when the given object is loaded using the mentioned diamond, we determine what damage occurs on it, i.e. how deep the diamond indents into it.
Classification of HRC hardness
- 40-45 HRC applies to axes, chisels, etc.
- 52-56 HRC determines common kitchen steel knives
- 55-62 HRC is a quality blade of a knife
- 59-61 HRC is already a category of very high-quality kitchen steel knife
- 65-67 HRC are very high-quality Japanese steel blades
- 66 HRC belongs to blades that are processed using powder metallurgy
Other scales of mechanical testing of metals
- Grodzinski hardness
- Vickers hardness
- Knoop hardness
- Brinell hardness
