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Rockwell Hardness

Friday, May 27th, 2011

Newage Indentron Digital Rockwell Hardness Tester 1
US $6,999.98

Wilson Instron B524T Digital Automatic Rockwell Twin Scale Hardness Tester Cert
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US $6,450.00

Antonik Clark AES 8 Digital Rockwell Superficial Hardness Tester N T Wilson
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US $4,450.00

175kg NEWAGE VERSITRON Rockwell Hardness Tester
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US $4,450.00

Wilson Rockwell Hardness Tester Model B 523 R
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US $4,000.00

Wilson Rockwell Superficial Hardness Tester Model No B505 S
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US $3,950.00

What is a Brinell Hardness tester and a rockwell Hardness tester?

these are used to measure the hardness of a metal
description of the device.

Rockwell:
The general Rockwell test procedure is the same regardless of the Rockwell scale or indenter being used. The indenter is brought into contact with the material to be tested, and a preliminary force (formally referred to as the minor load) is applied to the indenter. The preliminary force is usually held constant for a set period of time (dwell time), after which the depth of indentation is measured. After the measurement is made, an additional amount of force is applied at a set rate to increase the applied force to the total force level (formally referred to as the major load). The total force is held constant for a set time period, after which the additional force is removed, returning to the preliminary force level. After holding the preliminary force constant for a set time period, the depth of indentation is measured a second time, followed by the removal of the indenter from the test material. The measured difference between the first and second indentation depth measurements, "h", is then used to calculate the Rockwell hardness number.

Brinell:
Brinell hardness is determined by forcing a hard steel or carbide sphere of a specified diameter under a specified load into the surface of a material and measuring the diameter of the indentation left after the test.The Brinell hardness number, or simply the Brinell number, is obtained by dividing the load used, in kilograms, by the actual surface area of the indentation, in square millimeters.The result is a pressure measurement, but the units are rarely stated .

The Brinell hardness test uses a desk top machine to press a 10mm diameter, hardened steel ball into the surface of the test specimen. The machine applies a load of 500 kilograms for soft metals such as copper, brass and thin stock. A 1500 kilogram load is used for aluminum castings, and a 3000 kilogram load is used for materials such as iron and steel. The load is usually applied for 10 to 15 seconds. After the impression is made, a measurement of the diameter of the resulting round impression is taken. It is measured to plus or minus .05mm using a low-magnification portable microscope. The hardness is calculated by dividing the load by the area of the curved surface of the indention, (the area of a hemispherical surface is arrived at by multiplying the square of the diameter by 3.14159 and then dividing by 2). To make it easier, a calibrated chart is provided, so with the diameter of the indentation the corresponding hardness number can be referenced. A well structured Brinell hardness number reveals the test conditions, and looks like this, "75 HB 10/500/30" which means that a Brinell Hardness of 75 was obtained using a 10mm diameter hardened steel with a 500 kilogram load applied for a period of 30 seconds. On tests of extremely hard metals a tungsten carbide ball is substituted for the steel ball. Among the three hardness tests discussed, the Brinell ball makes the deepest and widest indentation, so the test averages the hardness over a wider amount of material, which will more accurately account for multiple grain structures, and any irregularities in the uniformity of the alloy.

The Brinell hardness test was one of the most widely used hardness tests during World War II [7]. For measuring Armour plate hardness the test is usually conducted by pressing a tungsten carbide sphere 10mm in diameter into the test surface for 10 seconds with a load of 3,000kg, then measuring the diameter of the resulting depression.

206RSD Rockwell Hardness Tester - 206 RSD Load Cell System