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Hardness Measurement

Hardness test procedure

Measurement of hardness for hardened steel requires high quality test equipment and accurate preparation of the surface
to ensure quality and to achieve accurate and correct measurements.

 

  1. Select test piece
    The test piece must be at least 8 times thicker than the impression depth.
  1. Cut test piece
    The test piece shall be cut with equipment that avoids heat impact on the test piece. 
    If the test piece is heated above 160 °C / 320 °F the test result is considered invalid. 
    Heat above the approved temperatures will affect the hardness of the steel.
  1. Polish the test surface
    The test surface must be polished and free from oxide before the test can commence. 
    See example below of a correct prepared surface:

                             Not OK                                                                                                     OK

 Polish the test surface

  1. Select correct test equipment
    The test equipment must be specifically made for testing of hardened steel. 

    See examples below:

 Correct test equipment Correct test equipment

The test is performed by applying a specified sphere with force to the prepared surface. The width of indention diameter specifies the hardness.
See example below:

 Brinell Hardness Test

The test shall be performed with a calibrated Brinell test equipment. With A 10 mm hard metal ball is forced into the surface 0,5-1 mm below the
surface of the steel piece, and with a force of 3 000 kg. The angle must be 90 degrees against the test surface.

NOTE!!!
Portable and manual test equipment is not accurate enough to get a trustworthy results and therefore not sufficient as measurement equipment.
See examples below:

 

Portable and manual test equipment               Portable and manual test equipment Portable and manual test equipment

 

Straightness

The deviation from straightness (arrow height) is measured with the bar resting on the horizontal surface. Arrow height is measured in the horizontal direction the length of the bar (L).

 

Straightness max 1,7 mm, q per meter. Which means a maximum of 5,1 mm on a steel with a length of 3000 mm.

q ≤ 0,17 % x L

 

 Straightness

 Save the instruction in pdf format here.