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Material Hardness Lab Report

Sam Sweeney

 Aim:

The aim of the experiment is to measure the hardness values of three materials: steel, cast

iron and aluminium usin the Leeb method! "nce these values are discovered, they will be

converted into two other methods as a cross reference, such as #ic$ers, %rinell or Roc$well!

Some bac$round information on the testin methods will be provided alon with the

e&uipment setup, calibration process, the procedure and results, conversion information,

conclusion and error report!

%ac$round 'nformation on the various hardness tests available:

Leeb

This method was created in ()*+ by leeb and brandestini and was desined with the aim ofprovidin portable hardness testin for metals! 't is commonly $nown as Leeb rebound- and

was oriinally an alternative to more complicated methods available at the time!

't wor$s by creatin an indentation on the surface of the material, usin a probe and

an indenter of specific eometry and si.e! The hardness value is derived from the enery

loss of an impact body on a metal sample, usin voltaes to calculate the velocity as it

proceeds throuh the measurin coil and when it rebounds!

/ositives:

• Small indentation of only 0!+mm

• 1uic$ test time of around 2 seconds

• /ortability

3eatives:

• /arts must have a ood finish and minimum weiht of +$!

• Must be perpendicular to surface, althouh can be used at different anles!

Brinell

"riinally proposed in ()00 by Swedish enineer 4ohan Auust %rinell, it was the first widely

used and standardised hardness test in enineerin and metallury! 't wor$s by calculatin a

scale of indentation on a material test5piece! Typically a (0mm diameter steel ball is used

whereas tunsten carbide may be used for harder materials!

/ositives:

• 6irst widely used to provide standardised results

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3eatives:

• Slow and not useful on hardened steel

• Lare indenter si.e which could damae a test5piece

Vickers

This method was created in ()2( by Robert L Smith and 7eore 8 Sandiland at #ic$ers Ltd

as an alternative to %rinell! 't wor$s, as with other methods, by measurin a materials ability

to resist plastic deformation, or indentation, from a standard source! The unit is called the

#ic$ers pyramid number 9H# or diamond hardness 9;/H

/ositives

•

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? /ress button to release the ball

? Record hardness readin

? Move probe slihtly to a different position and repeat the previous @ steps

? Record @ readins in total and calculate averae readin

? Tidy away e&uipment into its appropriate place

  8xperimental results:

Material HL( HL2 HL@ A#8RA78 8rror

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scale as they are not exactly con!ertible. %reat care must be ta$en to

reduce the li$eliness of these errors occurring.