HARDNESS TEST

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HARDNESS TEST

• EXPERIMENT 4
• Instructor M.Yaqub

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HARDNESS

• Hardness is the ability of a material to resist
  against wear or indentation.
• In HARDNESS TEST an indenter is used to penetrate
  in the sample by using a force.
• Less penetration means, material is hard.
• More penetration means, material is soft.
• Different Hardness test because of different
  indenter and force.

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HARDNESS TEST
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BRINELLHARDNESS TEST

• The brinell hardness testing equipment is used
  for the test.
• The INDENTER is a 1 - 10 mm Diameter (D) hardened
  steel ball.
• Applied force (P) is maximum 250 kg.

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ROCKWELL TEST

• In this test, Rockwell hardness number HR can be
  read directly from the machine.
• Several type of scales are available for Rockwell
  test, depends on the type of indenter and load.
  
• See table on next slide for different scales use
  different type and size of indenter and force.

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for example, Scale B uses 1/16 inch diameter
steel sphere as an indenter and 100 kg force.
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TEST PROCEDURE

• Apply a minor load of 10 kg.
• Then apply major load 60 to 150 kg according to
  the scale used for 4 to 5 seconds.
• Release the major load only.
• Machine will show the Rockwell Hardness Number HR
  on the machine.
• All these operation will be done by machine
  automatically.
• 100 number means most hard and 0 means least hard
• 1 division represents a penetration of 0.002 mm.
  

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RELATION BETWEEN TENSILE STRENGTH AND HARDNESS
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CONVERSION OF DIFFERENT HARDNESS SCALE