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Brinell hardness tester procedure.

Brinell hardness tester procedure:-

BRINELL HARDNESS TESTING

The Brinell hardness test is used for larger samples in materials with a coarse or inhomogeneous grain structure. This page describes the Brinell hardness test in detail and gives you practical information on how to apply it.


Brinell Test Machine Description:-

  1. The Brinell Hardness Tester consists of a loading system, the main screw, and a dial gauge.
  2. The loading system consisting of weights, leavers and a hydraulic dashpot and a plunger arrangement is enclosed in the cast iron body of the machine.
  3. The main screw is also protected from extraneous elements by a rubber bellow.
  4. It carries the test table on its top to hold the specimen and is actuated by a hand at the base.
  5. The machine is provided with two ball indenters (of sizes 2.5mm&5mm) to transmit the test load on to the specimen

DEFINITION OF THE BRINELL HARDNESS TEST:-

Today, the Brinell test is performed using a Brinell hardness test unit. The machine presses a tungsten carbide ball into the sample, and then optically measures the diameter of the impression.
  • Indenter sizes: 1, 2.5, 5 and 10 mm
  • Loads: From 1 kgf to 3000 kgf
  • Maximum hardness: 650 HBW

The Brinell hardness test method as used to determine Brinell hardness, is defined in ASTM E10. Most commonly it is used to test materials that have a structure that is too coarse or that have a surface that is too rough to be tested using another test method, e.g., castings and forgings. Brinell testing often use a very high test load (3000 kgf) and a 10mm diameter indenter so that the resulting indentation averages out most surface and sub-surface inconsistencies.

Common test forces range from 500kgf often used for non-ferrous materials to 3000kgf usually used for steels and cast iron. There are other Brinell scales with load as low as 1kgf and 1mm diameter indenters but these are infrequently used. 


Test Method Illustration 

D = Ball diameter 
d = impression diameter 
F = load 
HB = Brinell result 

Test Procedure

  1. The surface of the test specimen must be either machined, ground, lapped or polished.
  2. Set the machine to the required stage of the test load.
  3. Choose the indentor to be used and fasten it to the machine.
  4. Place the specimen on the test table and, apply a minor load of 10-kg-f on it by turning the hand wheel and bringing both the pointers on the dial gauge to the ‘set’ positions.
  5. Apply the major load (remaining part of the test load) on the specimen by turning the loading lever backward.
  6. Maintain the load on the specimen exactly for the specified dwell time (15 seconds) and then release it by turning the loading lever forwards.
  7. Take out the specimen and measure the diameter of the indentation formed on it by using the Brinell Microscope..

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