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Hardness Testing

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

Hardness Testing Equipment

Part 2: Brinell Hardness Testers

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Brinell Hardness Testing

The standard Brinell hardness test consists ofapplying a 3000kg load to a 10mm Tungsten Carbideball. This ball penetrates the surface of a material,

forming an indentation The diameter of the indentation is measured, and the

diameter is converted to Brinell hardness value(HBW)

The actual conversion is an equation that divides theload applied by the surface area of the indentation

Note: It is possible to use different loads and balldiameters, however it is not recommended. Alltesting for Cameron should be done using the

standard method.

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Brinell Hardness Testing

3 different types of Brinell testers are available,

bench type, radial arm, and bridge type.

The most accurate for large parts is by far the bridge

Brinell

For smaller parts, the bench type works just as well,

however many of Camerons parts are too large for this

ASTM E10 is the standard that covers Brinell

Hardness Testing

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Bench Brinell

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Bridge Brinell

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Radial Arm Brinell

Location: Oklahoma City

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Key Points in ASTM E10

3000kg load 1% (30kg)

10mm tungsten carbide ball

No steel balls to be used

Indentation Measurement Devices Type A Devices are microscopes that have movable

measuring lines with an attached measurement indicator,a computerized measurement system or a image analysis

measurement system Type B Devices are hand-held microscopes with the a

fixed measurement scale imprinted on the optical lens

Read two diameters on each impression, 90 apart The two diameters read on an impression shall be within

0.1mm

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Key Points in ASTM E10

Figure 1 shows the correct Indentation Spacingcriteria

Indentation Procedure

The applied test force isto be applied within1s to 8s

Once the full test forcehas been applied, it is to

be held for a 10s to 15s dwell time before the test force isreleased

Surface shall be prepared so the impression canbe accurately read

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Problems with Brinell Testing

Large load 3000kg

Thin walled parts will deflect, resulting in false hard

results

Mainly a problem on pipe, tube, or cylindrical parts

Large indenter 10mm ball

Moves a lot of material

Possible work hardening in nickel alloys

False, hard results

Large amount of error associated with reading theimpression (to be covered in detail later)

Automatic readers are more accurate than the

standard Brinell scope

10mm

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Advantages of Brinell Testing

Measures bulk properties

The large load and indenter test a large area compared to

other methods

This gives a better idea about the overall properties

Works well to correlate the strength of the material

Impressions can be re-read at a later time

Provided the impression has not been altered by re-heat

treating, grinding/finishing