Rockwell Hardness Testers FAQ
1. What is the principle of Rockwell Hardness testing?
Rockwell hardness testing using a 120 ° diamond cone or carbide ball (1 / 16 in diameter) ") as an indenter, the indenter is pressed into the surface of the specimen under the action of the initial test force Fo and the main test force F1. After removing the main test force, the residual increment h of indentation depth is measured with the initial test force Fo, and Rockwell hardness is calculated according to h value and constants N and S.
2. What are the Rockwell Hardess Tester Excution Standard?
International Standard：EN-ISO 6508
National Standard: GB/T 230.2
Clibration Speccification: JJS Z2245
3. What material can be tested with Rockwell Hardness testers?
Rockwell B Scale HRB: Copper alloys, soft steels, aluminum alloys, malleable iron, etc.
Rockwell C Scale HRC: Steel, hard cast irons, pearlitic malleable iron, titanium, deep case hardened steel, and other materials harder than B100.
Rockwell A Scale HRA: Cemented carbides, thin steel, and shallow case-hardened steel.
4. How to choose the scale of the Rockwell hardness tester?
5. What is the requirement of sample thickness?
The thickness of the test piece shall be at least 10 times the permanent indentation depth for diamond indenters and 15 times the permanent indentation depth for ball indenters, unless it can be demonstrated that the use of a thinner test piece does not affectnthe measured hardness value.
6. If we don't know the material hardness, which scale to use first?
7. What is the difference between Rockwell and Superficial Rockwell Hardeness?
They have different foce, the force of Superficial Rockwell Hardness Tester are much smaller.
8. What's the pros and cons between Manual and Color Touch Screen Rockwell tester?
Manual Rockwell Hardness Tester
1. Dial display, there is a reading error;
2. Cannot directly convert other hardness values;
3. Cumbersome operation and high technical requirements for operators;
4. Outdated shape, low end;
5. All kinds of human errors produced by human operations are larger.
Color Touch Screen Rockwell Dourometer:
1. Color digital display, reduce reading error;
2. Can directly convert other hardness values;
3. Simple operation, low technical requirements for operators, anyone who would use;
4. Stylish shape, high-end;
5. Automatic loading of motor, effectively reduce all kinds of artificial errors and equipment losses;
6. Automatic data preservation, no manual record.
9. Selection of Rockwell Hardness Scale
|Material of Specimen||Indenter||Scale||Test force (kg)||Drum wheel reading scale|
|High hardness or thin hard materials. Such as hard alloy, hardened thin steel belt, after carburizing hardened steel.||Diamond indenter||A||60||C|
|Medium to low hardness materials. Such as annealing low carbon steel, stainless steel, copper alloy, super hard aluminum alloy, malleable cast iron, etc. It is widely used Rockwell hardness scale.||1/16" Steel ball||B||100||B|
|Hardened and low-temperature tempered steel, cold hard cast iron, pearlitic malleable iron, titanium alloy, etc., and materials with a hardness value exceeding HRB100. It is the most widely used Rockwell hardness scale.||Diamond indenter||C||150||C|
|Surface-hardened steel, thin and hard steel, pearlitic malleable cast iron.||Diamond indenter||D||100|
|Cast iron, Aluminum alloy, Magnesium alloy, Bearing alloy.||1/8" Steel ball||E||100|
|Annealed brass, red copper, aluminum alloy, mild steel sheet.||1/16" Steel ball||F||60|
|Beryllium bronze, phosphor bronze, malleable cast iron, etc. (materials with HRB values close to 100).||1/16" Steel ball||G||150|
|Aluminum, zinc, lead and other soft metals.||1/8" Steel ball||H||60|
|Soft metal thin material, Bearing alloy.||1/8" Steel ball||K||150|
|Shallow surface hardened steel parts such as carburized steel, nitrided steel and surface quenched steel which are not easy be detected by Rockwell hardness testers; Small parts; Hard steel strips with thickness as thin as 0.15mm and high hardness workpieces requiring as little indentation as possible.||Diamond indenter||15N||15||N-T|
|Mild steel, stainless steel, copper alloy, aluminum alloy sheet and strip materials, thin-walled pipes, small parts, plating layer, and requirements of indefination as small as possible, low hardness workpieces.||1/16" Steel ball||15T||15||N-T|
|1/16" Steel ball||30T||30||N-T|
|1/16" Steel ball||45T||45||N-T|
N scale is used for materials similar to those detected by Rockwell scales C, A, and D, but limited to thin small specimens and specimens with shallow hardening depths.
T scale is used for materials similar to the Rockwell scales B, F, and G, but limited to thin small specimens and softer and lightly plated specimens.