Hardness is a test of a specific material; it is not a permanent physical property.
The resistance to indentation is measured by determining the depth of the indentation.
The basic physical hardness of materials is not permanent, you can change their physical properties by applying different types of pressure or heating them.
Hardness testing gives you the opportunity to determine the properties of a particular material. Physical properties include the three different things of strength, ductility, and resistance.
These properties are different for different materials. They can help you choose the most appropriate treatment for your particular material.
The basic definition of hardness testing is that "the electrical resistance of a particular material that exhibits permanent deformation can be determined by applying pressure, or by penetrating it into another material that is stiff".
Very important when drawing conclusions about hardness testing to evaluate quantitative values.
Quantitative values need to be assessed by keeping a few things: what is a given load on the indenter, a certain loading time and the duration of the load and the geometry of the indenter.
Things to consider for hardness testing:
Notes on Hardness Testing
Before choosing a hardness testing method, there are some important things to consider. These are simple characteristics of the material or thing required to perform the test. How hardness testing works:
Hardness testing is basically done by squeezing the material with the help of a heavy or large sized object. The loaded object is placed on the surface of the material to be tested.
After some resistance, the sample material will begin to deform.
Hardness is usually measured by the depth of the indenter or by the indentation left by the indenter.
The hardness test is performed by different tests, to measure the penetration depth of the indenter, the instrumented indentation test, the Rockwell hardness and the ball indentation hardness test are used.
To measure the depth of the indentation left by the indenter, Knoop, Brinell and Vickers are used.
Choose a test method:
Before performing a test, you need to choose a test method based on the physical properties of your sample.
The hardness of a material depends on its microstructure, shape, size, thickness, and many other factors.
In all material hardness tests, one sample under the indentation represents the whole. If you want to perform tests of different materials at once, you will need more impressions.
There are four main types of hardness tests used to measure the hardness of any material. Each test has its own requirements and brings different benefits.
There are different criteria for conducting each test. Before choosing a specific hardness test, there are some important things to consider.
Material - What is the type of material used to perform the hardness test and what are its physical properties.
Thickness - The thickness of the material is very important as the thickness of the material will suggest your testing method. The test is performed based on the thickness of the specific material.
Sample size - what is your sample size, sample size is very important for testing purposes. You can draw conclusions based on the sample size.
The shape of the sample - There are many different types of materials, each in a different shape or size. It is necessary to identify the shape of a particular material before performing a test, as the type of test depends on the shape of the sample.
Scale - The scale you use during testing can affect your results. Therefore, it is very important to choose the right scale to measure the sample.
Gage R&R - It is a measurement used to measure the accuracy of a sample result. It is a statistical tool used to measure the amount of variation in a device.
Which type of material is used for hardness testing?
The test material you selected meets the requirements. As you know, every test has some rules or standards, so your sample should meet the regulations.
The maximum hardness of the material is known prior to selection for testing.
Regardless of whether the sample is homogeneous or heterogeneous, the most appropriate test should be selected for it.
The dimensions of the material being tested should be calculated.
The number of available samples to be tested is mentioned.
Accuracy of results is very important in selecting a test.
Rockwell hardness test:
Among other tests, the Rockwell hardness test is known to be a very fast test. Usually used for metal materials. It was developed to control the production of specific materials. The Rockwell hardness test is determined by measuring the depth of the indentation. The measurement is made when the indenter is pressed firmly into the sample material under a certain load. Rockwell is typically used for large sample materials. It is also used to perform advanced tests such as HRC.
Vickers hardness test:
The Vickers hardness test is used to check the hardness of solid materials, especially metallic materials. It is measured by the length of the diagonal of an indented sample left at the force of a specific load applied to a diamond-shaped indenter. Hardness is measured by diagonal indentation with the help of formulas or tables.
Knoop hardness test:
Knop is an alternative test to Vickers. It is used to measure the hardness of micromaterials. I usually use it for brittle materials and testing the hardness of thin objects. The indenter used in this test is an asymmetrical rhombus, which is measured by the optical long diagonal.
Brinell hardness test:
The Brinell hardness test is used to test larger samples. The samples used in the tests had a uniform grain structure. The indentation will make a great impression on the sample with the help of carbide balls.
