Theory of hardness testingBack to overview
The Brinell method has the following advantages:
- The Brinell method can be used for testing non-homogeneous materials (e.g. castings), because the large ball comes into contact with many crystals (different metallographic constituents of the material), thereby forming a mechanical average value.
- A choice can be made between a large number of test forces and ball diameters for the widest variety of applications.
- Relatively large test indents that are easier to measure the rather small Vickers indentations.
- The specimen surface can be rough.
The Brinell method has the following disadvantages:
- The surface quality of the specimen must be good, because the indent is measured optically. This means that the test location must be prepared.
- High risk of deforming the material to be tested when testing in the macro range with high test loads (e.g. HBW 10/3000) and consequent risk of measuring errors due to wall formation. Therefore good illumination of the test indent is important for ensuring correct evaluation of the test indent (e.g. with the aid of a ring light).
- Limitation in applying the method on thin specimens of very hard materials (see Brinell method, minimum specimen thickness).
- The process is slow (by comparison with the Rockwell method). The test cycle takes somewhere between 30 and 60 seconds, not including the time taken to prepare the specimen.