Brinell hardness testing was invented by Dr. J. A Brinell from Sweden in 1900. It is an old method of hardness test which is commonly used today. Brinell hardness testing is mainly used for determining the hardness of castings and forgings which have a grain structure too course for either Vickers or Rockwell testing.
Brinell hardness testing is usually carried out on large parts. Moreover, this test is virtually able to test all types of metals by varying the ball size and test force. Brinell values are considered test force independent only if the relationship of the ball size/test force is the same.
In some contries including USA, Brinell testing is usually carried out on iron and steel casting by using a 3000Kg test force along with a 10mm diameter carbide ball. Therefore, the typical Brinell testing range used is 500 up to 3000 kg with 5 up to 10 mm carbide balls.
Meanwhile, the Brinell hardness testing in Europe is carried out by using forces and carbide balls at wider range. N this area, Brinell test is commonly performed on small parts by utilizing a 1 mm carbide ball as well as a test force at 1 kg. These low load tests are generally known as baby Brinell tests.
What are the Methods of Brinell Hardness Testing? The method of Brinell hardness testing has indenting the test material along with 1 hardened steel or carbide ball with 10 mm diameter. It is aimed to load 3000kg. For softer material, you can reduce the load to 1500 kg or even 500 kg in order to avoid the excessive indentation. For iron and steel, the full load is commonly applied for 10 or 15 seconds.
Meanwhile, for other metals, the full load is around 30 seconds. The indentation diameter which is left in the test material is usually measured with a low power microscope. The Brinell hardness number is obtained by dividing the load used by the indentation surface area.
The impression diameter is the average of two readings at the right angles. The use of a Brinell hardness number table is very helpful in simplifying the determination of the Brinell hardness. Brinell hardness testing number which is well-structured can show the conditions of the test and may look like “75 HB 10/500/30”. It means that a Brinell Hardness of 75 was achieved by using 10 mm diameter hardened steel along with 30 seconds of handling 500 kilogram load.
Tests of Brinell hardness testing on really hard metals, you can substitute the tungsten carbide ball with the steel ball. Different from any other hardness test methods, the Brinell ball is able to make the widest and deepest indentation. As a result, the test averages the hardness over a greater amount of material.
It is able to provide you more accurate account for some different grain structures and any other regularity in the material uniformity. This is suitable for obtaining the bulk or macro-hardness of a material especially material with various structures.
Applications
Due to the wide range of test force, the Brinell hardness testing can be applied for virtually any metallic material. The strengths of this application include on scale which can cover the whole hardness range. Its wide arrange of test forces and ball size is to fit every application. Meanwhile, the weaknesses include slow testing around 30 seconds and it needs well test point finish for accurate measurement.
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