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Hardness Testing

For information regarding this presentation, please contact Dan Emelander (Metallurgist) 713-939-2672

Hardness Testing Equipment

Part 3: Reading a Brinell Impression

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Reading the Impression

Brinell Scopes

Light source MUST be attached!

Computerized OpticalScanner

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Comparison of Equipment

Advantages

Relatively inexpensive More portable

More durable

Disadvantages

High variability (~10% ofBrinell value)

Can only read at 0.05mmincrements

Inspectors sometimes donot measure 2 diameters

Advantages

Low variability, only 2% ofBrinell value

Can read to 0.01mm

Always reads 8+ diameters

Disadvantages Less portable (but still very

portable)

Higher cost; ~$4000

Less durable

Brinell ScopesComputerized Optical

Scanner

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Using the Brinell Scope

Turn on the flashlight, or lighting system The flashlight should be attached to the scope! Holding the

light, or not having a light is unacceptable

Place the scope on the part No rocking should take place, it should rest flat

Read the impression Measure 2 diameters

Diameters are to be 90 apart

Average the diameters, and use the table listed inASTM E10 to convert the diameter into a HBWnumber

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Oval Indentations

Cameron requires that when the difference betweentwo diameters is greater than 0.1mm, it is invalid

Oval indentations are a key indicator that the setup ofthe tester was not acceptable

Oval indentations are most often caused by: Bottom support not directly below test location

Tester not perpendicular to the test piece

Movement during the test

Test surface not flat

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Which Indentation is Invalid?

4.15

4.20

A. B.

C. D.

4.10

4.25

4.15

4.15

4.15

4.25

Difference =0.05

Difference =0.10 Difference =0.00

Difference =0.15

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Using the Optical Scanner

Once the scanner is turned on and calibrated: Place the scanner over the indentation

The scanner should rest flat on the surface, no rocking

should occur

Make sure the entire indentation is visible on the screen, andpress the button

The software will now display the hardness value on thescreen

It will also kick out oval readings, or if the surface is too roughto get a good reading

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Reporting a Brinell Hardness

The standard Brinell hardness number shall bereported using 3 significant numbers, followed byHBW.

Example: 237 HBW Non-standard tests shall be reported using the above

notation, followed by the items below, separated by a/: The load used

The ball diameter used (mm)

The time the load was held

300 HBW 1500 / 5 / 7 A 300 HBW was obtained using a 1500kg load, a 5mm

tungsten carbide ball, and the load was applied for 7 seconds.