Methods of testing the hardness of steel
One of the methods of testing the hardness of steel is the Rockwell test. The hardness measurement consists of testing the deformation resulting from forcing an indenter into the tested material. Rockwell hardness is defined by the indentation depth obtained during the two-step test. The result of the measurement is read in HR unit of hardness, to which the scale comes. For hand tools, the most common scales are B and C. The C scale is used to determine the hardness of iron alloys, while the B scale is used to determine the hardness of aluminium, copper, brass and other soft steel. The high hardness for hand tools varies between 55 and 60 HRC.
A detailed description of the method of measurement with the Rockwell method is described in the Polish Standard PN-EN ISO 6508.
Worth knowing
The quality of hand tools results from the chemical composition of steel and the heat treatment process used. Well-chosen and used technologies allow for an increase in hardness and thus the durability of the tools. One such technology is hardening. It consists in heating the material and then cooling it quickly, e.g. with the help of electric current (induction hardening) or fire (flame hardening). The process carried out in this way causes a change in the physicochemical properties of steel, e.g. hardness, yield strength and resistance. According to the physicochemical properties of steel alloys, resistance to cracking and crumbling decreases together with an increase in hardness. Therefore, the surface layer of the working part of a given tool is most often hardened.
Pliers are an example of a tool which cutting edges are subject to rapid wear.
Good quality products have hardened steel edges additionally subjected to the induction hardening process, just like Högert Technik pliers series
which include:
