Rockwell Test For Heat Treating
Rockwell Test… What is it?
Hardness is a characteristic of a material, not a fundamental physical property. It is defined as the resistance to indentation, and it is determined by measuring the permanent depth of the indentation. In order to test the hardness of a material either before and or after a heat treating process has been performed, one would utilize a special tool called a Rockwell tester. In 1919 Hugh and Stanley Rockwell invented and patented the Rockwell tester. Hugh and Stanley were not related and merely co-workers with the same surname. The Rockwell tester utilizes a penetrator made of metal or diamond and measures hardness by determining the depth of penetration to the material.
Hardness testing is used in a number of industries and on a number of materials but is most common in checking the hardness of metals. It is important to know the hardness of a metal in order to determine its overall strength under load, its resistance to wear and its overall ability to be used for your required purpose. Most quality tools, knives, axes and machine tooling are hardened through a heat treating process (more info found here) in order to keep them from bending or becoming unusable.
See our Rockwell standard hardness scales and applications chart below.
|
Scale symbol |
Indenter |
Major load (kgf) |
Typical applications |
|
A |
Diamond (two scales—carbide and steels) |
60 |
Cemented carbides, thin steel, shallow case-hardened steel |
|
B |
1.588 mm ball |
100 |
Copper alloys, soft steels, aluminum alloys, malleable iron |
|
C |
Diamond |
150 |
Steel, hard cast irons, pearlitic malleable iron, titanium, deep case-hardened steel, other materials harder than HRB 100 |
|
D |
Diamond |
100 |
Thin steel and medium case-hardened steel and pearlitic malleable iron |
|
E |
3.175 mm ball |
100 |
Cast iron, aluminum and magnesium alloys, bearing metals |
|
F |
1.588 mm ball |
60 |
Annealed copper alloy, thin soft sheet metals |
|
G |
1.588 mm ball |
150 |
Phosphor bronze, beryllium copper, malleable irons. Upper limit HRG 92 to avoid possible flattening of ball |
|
H |
3.175 mm ball |
60 |
Aluminum, zinc, lead |
|
K |
3.175 mm ball |
150 |
Bearing metals and other very soft or thin materials. Use the smallest ball and heaviest load that does not produce an anvil effect. |
|
L |
6.35 mm ball |
60 |
Bearing metals and other very soft or thin materials. Use the smallest ball and heaviest load that does not produce an anvil effect. |
|
M |
6.35 mm ball |
100 |
Bearing metals and other very soft or thin materials. Use the smallest ball and heaviest load that does not produce an anvil effect. |
|
P |
6.35 mm ball |
150 |
Bearing metals and other very soft or thin materials. Use the smallest ball and heaviest load that does not produce an anvil effect. |
|
R |
12.70 mm ball |
60 |
Bearing metals and other very soft or thin materials. Use the smallest ball and heaviest load that does not produce an anvil effect. |
|
S |
12.70 mm ball |
100 |
Bearing metals and other very soft or thin materials. Use the smallest ball and heaviest load that does not produce an anvil effect. |
|
V |
12.70 mm ball |
150 |
Bearing metals and other very soft or thin materials. Use the smallest ball and heaviest load that does not produce an anvil effect. |