Hardness testing involves applying a constant load via a rounded or pointed object, under controlled conditions, to create an indentation in a metal surface. This is then measured to determine the hardness of the material.
Hardness affects a wide range of physical characteristics, such as how much the metal will wear, scratch or stand up to stress.
There are various types of hardness testing; we concentrate on three in particular – Rockwell, Brinell and Vickers.
Rockwell Hardness Testing
This is probably the most frequently used hardness test – both within laboratories and on production sites using a portable hardness tester. The test is relatively quick and allows you to see where a metal lies on one of a number of Rockwell hardness scales.
Each scale uses different loads or indenters and allows us to test harder or softer materials. For example, the HRB scale is used for aluminium, brass, and soft steels, while HRC is used on harder steels.
Brinell Hardness Testing
This test is often used for rough or uneven materials where one of the other methods wouldn’t work well. It generally uses a larger load than other tests, in the range of 500 kg to 3,000 kg. It also uses a larger indenter such as a 5 or 10 mm tungsten carbide ball.
This test makes a relatively deep, wide indentation in the material, which means it tests the average hardness over a larger area than some of the other tests.
Vickers Hardness Testing
Where the other tests use a ball-shaped indenter, the Vickers hardness test uses one shaped like a pyramid. Like the other tests, the indenter is placed under a load and the permanent indentation is measured. However, this test often uses much lighter loads and can be used on softer materials.
This is a very precise test and is often used for what’s known as microhardness testing – with very thin or small samples.
These testing methods are just some of those we employ to ensure our clients have safe products that are fit for purpose. If you are not certain what sort of hardness testing you require, get in touch today.