The Commonly Used Comparison Table of HV≈HB≈HRC Hardness Is Clear at A Glance.

Hardness refers to the ability of a material to resist local deformation, especially plastic deformation, indentation or scratching. It is an indicator for measuring the hardness or softness of materials. Here is the comparison table of Vickers hardness, Brinell hardness and Rockwell hardness for you. Please save it quickly!

Common HV = HB = HRC hardness comparison table.

The data in this table is sourced from the German standard DIN 50150.

Hardness of metallic materials

It refers to the ability of a material to resist local deformation, especially plastic deformation, indentation or scratching. It is an indicator for measuring the hardness or softness of materials.

Depending on different testing methods, hardness can be divided into three types.

① Scratch hardness. It is mainly used to compare the hardness and softness of different minerals. The method is to select a rod with one hard end and one soft end, and then scratch the tested material along the rod. The hardness or softness of the tested material is determined according to the position where the scratch appears. Qualitatively speaking, the scratch made by a hard object is long, while that made by a soft object is short.

② Indentation hardness. It is mainly used for metallic materials. The method is to press a specified indenter into the tested material with a certain load, and then compare the hardness or softness of the tested material according to the degree of local plastic deformation on the material surface. Due to differences in indenters, loads and load duration, there are several types of indentation hardness, mainly including Brinell hardness, Rockwell hardness, Vickers hardness and microhardness.

③ Rebound hardness. It is mainly used for metallic materials. The method is to let a specially made small hammer freely fall from a certain height to impact the specimen of the tested material, and then determine the hardness of the material by measuring the amount of strain energy stored (and then released) during the impact process of the specimen (measured by the rebound height of the small hammer).

The most commonly seen Brinell hardness, Rockwell hardness and Vickers hardness of metallic materials belong to indentation hardness. The hardness value represents the ability of the material surface to resist the plastic deformation caused when another object is pressed into it. When measuring hardness by the rebound method (Shore hardness, Leeb hardness), the hardness value represents the magnitude of the elastic deformation function of the metal.

Brinell Hardness

Use a hardened steel ball or cemented carbide ball with a diameter D as the indenter, press it into the surface of the test piece with the corresponding test force F. After the specified holding time, remove the test force and obtain an indentation with a diameter of d. Divide the test force by the indentation surface area, and the resulting value is the Brinell hardness value, which is represented by the symbol HBS or HBW.

The difference between HBS and HBW lies in the indenters. HBS indicates that the indenter is a hardened steel ball and is used to measure materials with Brinell hardness values below 450, such as mild steel, gray cast iron and non-ferrous metals. HBW indicates that the indenter is cemented carbide and is used to measure materials with Brinell hardness values below 650.

For the same test block, when other test conditions are exactly the same, the results of the two tests are different. The HBW value is often greater than the HBS value, and there is no quantitative rule to follow.

Since 2003, China has adopted international standards equivalently and canceled the steel ball indenter, and all adopted cemented carbide ball indenters instead. Therefore, HBS has been discontinued, and HBW is used to represent the symbol of Brinell hardness. In many cases, Brinell hardness is simply represented by HB, which refers to HBW. However, HBS can still be seen in literature and papers from time to time.

The Brinell hardness measurement method is applicable to cast iron, non-ferrous alloys, and various annealed and quenched and tempered steel products. It is not suitable for measuring specimens or workpieces that are too hard, too small, too thin or whose surfaces are not allowed to have large indentations.

Rockwell Hardness

A diamond cone with a cone apex angle of 120° or a hardened steel ball is used as the indenter in combination with loads. The indenter is pressed into the specimen under the action of an initial load of 10 kgf and a total load (i.e., the initial load plus the main load) of 60, 100 or 150 kgf successively. After the action of the total load, the hardness is represented by the difference between the indentation depth when the main load is removed while the initial load is retained and the indentation depth under the action of the initial load.

The Rockwell hardness test employs three test forces and three indenters, and there are a total of 9 combinations among them, corresponding to 9 scales of Rockwell hardness. The applications of these 9 scales cover almost all commonly used metallic materials. The commonly used ones are HRA, HRB and HRC, among which HRC is the most widely used. The application range of the HRC scale is from 20 to 70 HRC. When the hardness value is less than 20 HRC, as the conical part of the indenter is pressed in too much and the sensitivity decreases, the HRB scale should be used instead at this time. When the hardness of the specimen is greater than 67 HRC, the pressure on the tip of the indenter is too large, the diamond is prone to damage, and the lifespan of the indenter will be greatly shortened. Therefore, generally, the HRA scale should be used instead. The Rockwell hardness test is simple and quick to operate, with small indentations, and it can test the surfaces of finished products as well as harder and thinner workpieces. Due to the small indentations, for materials with uneven microstructure and hardness, the hardness values fluctuate greatly, and the accuracy is not as high as that of the Brinell hardness. Rockwell hardness is used to measure the hardness of steel, non-ferrous metals, cemented carbides and so on.

Vickers Hardness
The measurement principle of Vickers hardness is similar to that of Brinell hardness. A diamond square pyramid indenter with an included angle of 136° between the opposite faces is used. Press it into the surface of the material with the specified test force F. After maintaining it for the specified time, remove the test force. The hardness value is represented by the average pressure on the unit surface area of the square pyramid indentation, and the marking symbol is HV.

The measurement range of Vickers hardness is wide, and it can measure materials with a hardness in the range of 10 - 1000 HV. It has small indentations and is generally used to measure thinner materials and surface hardened layers such as carburized and nitrided layers.

Leeb Hardness
An impact body equipped with a tungsten carbide ball head of a certain mass impacts the surface of the test specimen under the action of a certain force and then rebounds. Due to the different hardness of materials, the rebound speed after impact is also different. Permanent magnetic materials are installed on the impact device. When the impact body moves up and down, the peripheral coil induces an electromagnetic signal proportional to the speed, which is then converted into the Leeb hardness value through electronic circuits, and the symbol is marked as HL.

The Leeb hardness tester does not require a workbench. Its hardness sensor is as small as a pen and can be directly operated by hand. It can easily detect both large and heavy workpieces as well as workpieces with complex geometric dimensions.

Another advantage of Leeb hardness is that it causes very light damage to the product surface and can sometimes be used as non-destructive testing. It has uniqueness in hardness testing in all directions, in narrow spaces and at special positions.