The hardness, such as the HRC hardness, of a material is technically the resistance that a material offers when another material penetrates it.
\nThere are various methods for determining the hardness of a material. As a rule, a very hard material (e.g. diamond) is used to penetrate a softer material (e.g. steel). The effect on the softer material then gives an indication of its hardness.<\/p>\n
The Rockwell measuring method is generally used for blades and knives. Its result is given in the unit HR. As sword steel is relatively hard, the C scale method is used. The result is therefore given in the unit HRC.
\nTo put it simply, a cone-shaped diamond is driven into the steel to measure how deep the diamond penetrates.<\/p>\n
Blades usually have a value between 40 and 65 HRC.
\nA hardness of 60 is already a decent value and at over 62 HRC the air becomes thin, as most sword blades have a lower HRC value. Only very few reach a value above 65 HRC.
\nFor orientation: The hardness of a stainless steel knife blade is usually around 50 HRC.<\/p>\n
Incidentally, the Rockwell method only allows values in the range between 20 and 70 HRC. So there is no value above 70 HRC!<\/p>\n
It is not a rule that the steel with the higher HRC hardness value is the better steel for a blade. It depends very much on which steel is used. Some types of steel are very hard but brittle and are therefore not suitable for blades.<\/p>\n
The HRC value is often given as a guide. However, a sword blade should never be judged by this one value alone.<\/p>\n
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You can find more information on the individual types of steel used for swords in our article\u00a0Blade steel types of Samurai swords<\/a>.<\/p>\n