Rockwell Hardness Testers FAQ
| 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. | |||||
| N: Diamond cone = 100 h = depth after pressing N: Quenched steel ball = 130 S = depth of 2 um per unit of Rockwell hardness |
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| Material of Speciment | Indenter | Scale | Test Force（kg） | Drum Wheel Reading Scale | ||
| What are the Rockwell Hardess Tester Excution Standard? | International Standard：EN-ISO 6508 National Standard: GB/T 230.2 Clibration Speccification: JJS Z2245 | High hardness or thin hard material. Such as hard alloy, hardened thin steel belt, after carburizing hardened steel. | Diamond indenter | A | 60 | C |
| 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. |
Medium and low hardness materials. Such as annealing low carbon steel, stainless steel, copper alloy, super hard aluminum alloy, malleable cast iron and so on. Is widely used Rockwell hardness ruler. | 1/16＂Steel ball | B | 100 | B |
| How to choose the scale of the Rockwell hardness tester? | Attached table | Hardened and low-temperature tempered steel, cold hard cast iron, pearlite malleable iron, titanium alloy, etc., and materials with hardness values exceeding HRB100. Is the most widely used Rockwell hardness scale | Diamond indenter | C | 150 | C |
| 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 affect the measured hardness value. | Surface-hardened steel, thin and hard steel, pearlite malleable cast iron | Diamond indenter | D | 100 | |
| If we don't know the material hardness, which scale to use first? | HRA | Cast Iron, Aluminum Alloy, Magnesium Alloy and Bearing Alloy | 1/8＂Steel ball | E | 100 | |
| What is the difference between Rockwell and Superficail Rockwell Hardeness? | They have different foce, the force of Superficial Rockwell Hardness Tester are much smaller. | Annealed brass, red copper, aluminum alloy, mild steel sheet. | 1/16＂Steel ball | F | 60 | |
| Beryllium bronze, phosphor bronze, malleable iron, etc. (materials with HRB values approaching 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 easily detected by Rockwell hardness tester; 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 | ||
| Diamond indenter | 30N | 30 | N—T | |||
| Diamond indenter | 45N | 45 | N—T | |||
| Mild steel, stainless steel, copper alloy, aluminum alloy sheet with materials, thin-wall pipes, small parts, plating layer and requirements of indentation 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 |
