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Brinell hardness

The Brinell method is one of the main methods of determination of material hardness referring to pressing-in methods.

The test is carried out as follows:
– at first a sample is brought to the indenter;
– then the indenter is pressed into the sample with fade-in loading for 2 -8 seconds;
– after achievement of the maximum value the loading to the indenter is maintained for a certain time interval;
– finally the applied loading is removed, the sample is taken away from the indenter and the diameter of the resulting impression is measured.

As indenters the balls made from firm alloy with diameters 1, 2, 2.5, 5 and 10 mm are used. The loading value and the diameter of a ball are chosen depending on the studied material.

At the choice of test conditions it is necessary to consider that the sample thickness should exceed the indenter pressing-in depth at least in 8 times. It is also important to control an impression diameter which is to be ranging from 0.24D to 0.6D (D — diameter of an indenter).

By reference documents the following parameters are defined:
– indenter diameter;
– pressing-in time;
– maximum loading resistance time;
– minimum sample thickness;
– minimum and maximum impression diagonals;
– maximum loadings;
– group of a tested material.

Comparison of polyamides by Brinell hardness