Brinell Hardness Testing
The Brinell method is a time-honoured approach to assessing the hardness of materials, particularly for larger samples like castings, forgings, and coarse materials. One of its advantages is that it employs a larger indenter diameter, which reduces the influence of surface irregularities and structural differences that can impact results.
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Compared to other hardness tests, which can yield different readings depending on the location on the material's surface due to its variability and roughness, the Brinell test measures bulk metal hardness. By utilizing a broader indentation, it provides a more accurate representation of the material's hardness.
The Brinell method creates a wide and deep indentation on the material, enabling it to evaluate the average hardness over a larger surface area than other testing methods. Materials such as pre-heat treated steel, non-ferrous metals, castings, and forgings can all benefit from Brinell hardness testing.
Basic Procedure
The Brinell Hardness Test is a straightforward process that is often applied to materials with rough structures, like cast irons or forged metal samples.
During the test, a 5mm or 10mm round carbide ball is pressed into the material using a very high test load, usually between 750kg and 3000kg. This action creates an indentation that is subsequently measured and analyzed using a microscope, yielding an average result based on the Brinell Hardness Number scale.
Test Methods
EN ISO 6506-1 and ASTM E10 are two widely recognized standards for Brinell hardness testing.
EN ISO 6506-1 is a European standard that specifies the requirements for metallic materials' Brinell hardness testing. It outlines the testing method, equipment, calibration, and procedures for determining the Brinell hardness of metallic materials using test forces between 1.96 N and 29420 N.
ASTM E10 is an American Society for Testing and Materials (ASTM) standard that specifies the standard test method for Brinell hardness of metallic materials. This standard describes the testing procedure, the testing machines and indenter requirements, and the calculation method of the Brinell hardness number. It covers a wide range of test forces, from 1 kgf to 3000 kgf, and various indenter sizes, from 1 mm to 10 mm.
Both standards are widely used in industrial settings to ensure that materials meet certain hardness requirements and to facilitate the comparison of hardness test results across different laboratories and testing equipment.