Indentation area
The test surface is the area where the permanent indentation is made in optical hardness tests. It is used to determine the hardness value.
Physical-Chemical Mechanism of Action
In optical hardness testing, a measuring head is pressed onto the material surface with a fixed force to leave a permanent indentation. The size of this area (test surface) affects the accuracy of the hardness determination.
Metallurgical Relevance & Welding Risks
A test surface that is too small can lead to inaccurate hardness readings, as it is not representative of the entire workpiece. This can cause errors in quality assurance and lead to non-compliance with specifications.
Workshop Practice & Instructions
The test surface should be large enough to fully cover the measuring head. For steel, areas from 1 mm² to 2 mm² are typically used. The exact size depends on the material and the testing method used.