Brinell Hardness Testing Machine:

The Brinell scale characterizes the indentation hardness of materials through the scale of penetration of an indenter, loaded on a material test-piece. It is one of several definitions of hardness in materials science.

Proposed by Swedish engineer Johan August Brinell in 1900, it was the first widely used and standardised hardness test in engineering and metallurgy. The large size of indentation and possible damage to test-piece limits its usefulness.

The typical test uses a 10 millimetres (0.39 in) diameter steel ball as an indenter with a 3,000 kgf (29 kN; 6,600 lbf) force. For softer materials, a smaller force is used; for harder materials, a tungsten carbide ball is substituted for the steel ball. The indentation is measured and hardness calculated as:

where:

P = applied force (kgf)

D = diameter of indenter (mm)

d = diameter of indentation (mm)

The BHN can be converted into the ultimate tensile strength (UTS), although the relationship is dependent on the material, and therefore determined empirically. The relationship is based on Meyer's index (n) from Meyer's law. If Meyer's index is less than 2.2 then the ratio of UTS to BHN is 0.36. If Meyer's index is greater than 2.2, then the ratio increases.

BHN is designated by the most commonly used test standards (ASTM E10-12 and ISO 6506–1:2005 ) as HBW (H from hardness, B from brinell and W from the material of the indenter, tungsten (wolfram) carbide). In former standards HB or HBS were used to refer to measurements made with steel indenters.

HBW is calculated in both standards using the SI units as

where:

F = applied force (N)

D = diameter of indenter (mm)

d = diameter of indentation (mm)

Features:

• Low Load Brinell up to 187.5 kgf
• Full Load Brinell up to 3000 kgf
• Built-in Optical Measurement System
• Automatic Measurement Option
• RS232C Output
• Automatic Test Cycle Option
• X-bar And Range Output

Procedure:

The Brinell test, consists of applying a constant load or force, usually between 500 and 3000 Kgf, for a specified time (from 10 - 30 seconds) using a 5 or 10 mm diameter tungsten carbide ball. The load time period is required to ensure that plastic flow of the metal has ceased. Lower forces and smaller diameter balls are sometimes used in specific applications. Similar to Knoop and Vickers testing, the Brinell test applies only a single test force. After removal of the load, the resultant recovered round impression is measured across diagonals at right angles and is usually recorded millimeters using a low-power microscope or an automatic measuring device.

The actual Brinell hardness (BHN) is calculated by factoring the indent size and the test force however it is not necessary to make the actual calculation for each test. Calculations have already been made and are available in tabular form for various combinations of diameters of impressions and load. In addition various forms of automatic Brinell reading devices are available to perform these tasks.Brinell testing is typically used in testing aluminum and copper alloys (at lower forces) and steels and cast irons at the higher force ranges. Highly hardened steel or other materials are usually not tested by the Brinell method, but the Brinell test is particularly useful in certain material finishes as it is more tolerant of surface conditions due to the indenter size and heavy applied force. Brinell testers are often manufactured to accommodate large parts such as engine castings and large diameter piping.