Hardness testing is a key way to predict the results of heat treatment, or how quickly the material will crack or buckle under pressure. Testing of metals and materials’ hardness follows four basic methods: Brinell, Vickers, Rockwell, and Leeb. Select one of the following four methods, based on the type of job you have.
The Brinell Test
The Brinell method of hardness testing has been around since 1900 and was the first popular and standardized hardness test for engineers and metallurgists. Hardness is tested by using a heavy indenter to penetrate a selection of test material. Usually a 10mm diameter steel ball is projected at a force of 3,000 kgf into the material needing to be tested. The force (kgf) is the divided into a formula including both the diameter of the indenter and the diameter of the indentation. The result is a Brinell Hardness Number (BHN).
The Vickers Test
The Vickers method came along a generation after Brinell, but is easier to use and generally returns more accurate calculations that the Brinell test since its calculations can be done no matter what size the indenter is. The Vicker test is versatile – it can be used for all metals – and features a wide scale.
The Rockwell Test
Rockwell testing was first developed in 1914 in order to quickly identify the effects of heat treatment upon steel bearings. The Rockwell method actually uses two “loads” or two points of impact, the difference between which is measured to determine the hardness of the material. The first load establishes the point from which you will measure, and the second load is the measuring load. The deeper the impression, the softer the material, and vice versa. The Rockwell method is popular due to is efficiency, reliability, and small impression left on the material. In this regard, the Rockwell test is a nondestructive test.
The Leeb Test (Portable)
Leeb hardness testing is unique for its portability and ability to test large areas of material. The previous three methods can only be done at a fixed location. Leeb testers provide efficiency, convenience and cost savings.