It is no secret to anyone that in the industry, before putting something on sale, products are inspected. This is necessary in order to establish the shelf life of the product, its performance. One of the criteria for the performance of parts is their hardness. Hardness is measured using special devices - hardness testers.
Hardness is usually measured in laboratories using hardness testers in research institutes or in manufacturing. There are several types of hardness testers that use different methods when measuring, but their essence is similar. Each hardness tester usually has a stage on which the test sample is placed, and an indenter - a tip, a body pressed into this sample, which must be harder than the test material (this is a prerequisite). For each measurement, you can set different conditions - indenter size, load, load time. Depending on them, the device can show different hardness.
Brinell's method
An indenter in the form of a ball (steel) is pressed into the investigated body, which leaves an imprint in the form of a round fossa. The diameter (to be more precise, the area) of the print determines the hardness. That is, the harder the material, the smaller the print, and vice versa.
Rockwell method
This method uses several indenters depending on the load. Either it is also a ball or a cone. And there are 11 scales for measuring hardness. Each scale is defined by a combination of indenter and load. Hardness in this method is defined as the difference in the depth of penetration of the tip - the first penetration is preliminary (usually 10 N), the second is the main one.
Vickers method
The Vickers hardness test is considered to be more successful because it is more accurate and applicable to a wide range of materials. In addition, they can carry out measurements in microvolumes, which is also very important. The indenter used here is a diamond tetrahedral pyramid. Hardness is also determined by the area of the resulting print.
In the modern world, the demand for hardness testers is quite large, so a large number of them are produced. And of course, more and more new methods appear on the basis of which hardness testers work. These are, for example, ultrasonic (a diamond pyramid is introduced into the test body with a certain load and at the same time vibrates - the vibrations are measured and thus determine the hardness) and dynamic (the hardness is determined by measuring the energy loss of the impact body). In addition, combined methods are used.
