Differences Between Rockwell Hardness and Vickers Hardness

The use of material hardness involves different scales, today we are going to focus on two types of hardness scales or units – what’s the difference between Rockwell hardness and Vickers hardness?

What is Rockwell Hardness

Rockwell hardness is an index to determine the hardness value based on the plastic deformation depth of the indentation. It is expressed as HR with 0.002 mm as a hardness unit. Using different indenters and different test forces in the Rockwell hardness test will produce different combinations (HRA to HR45Y), corresponding to different scales of Rockwell hardness. There are three scales commonly used, and their applications cover almost all commonly used metal materials. These three scales are A, B, and C, namely HRA, HRB, and HRC, which should be represented by scales with different hardness ranges according to the hardness of the experimental materials:

1. HRA is the hardness obtained by using a 60 kg load and diamond cone indenter, which is used for materials with higher hardness. For example steel sheet, and cemented carbide.

2. HRB is the hardness obtained by using a 100 kg load and a 1.5875mm diameter hardened steel ball, which is used for materials with low hardness. For example mild steel, non-ferrous metal, annealed steel, etc.

3. HRC is the hardness obtained by using a 150 kg load and diamond cone indenter, which is used for materials with higher hardness. For example quenched steel, cast iron, etc. Note: Rockwell hardness value is an “unnamed number” with no unit. Therefore, it is incorrect to call Rockwell hardness how many degrees. Its representation method is hardness data+hardness symbol, such as 50HRC.

What is Vickers Hardness

Vickers hardness is a standard of material hardness. It was first put forward by British scientist Vickers and expressed as HV. Vickers hardness test is mainly used for the small-load Vickers hardness test in the field of material research and is a scientific test mainly used to test the hardness of small precision parts, the hardness of the surface hardening layer, and the depth of the effective hardening layer, the surface hardness of the coating, the hardness of thin sheet materials and thin wire materials, the hardness near the blade, and the hardness of dental materials. Because the test force is small and the indentation is small, the appearance and service performance of the sample can not be affected. Vickers hardness tester can measure almost all metal materials used in industry, from very soft materials (several Vickers hardness units) to very hard materials (3000 Vickers hardness units). The value in front of HV is the hardness value, and the value behind HV is the test force. If the holding time of the test force is not the usual 10-15 seconds, it is also necessary to mark the holding time after the test force value. For example, 600HV30/20 means using the test force of 30 kg force for 20 seconds to obtain a hardness value of 600.

Differences Between Rockwell Hardness and Vickers Hardness

1. Rockwell hardness is easy to operate, can read directly, and has a small indentation. It is suitable for batch and finished product production, but it requires multi-point testing to ensure accuracy. Vickers hardness test has a wide range of measurements, covering almost all kinds of materials from soft materials to superhard materials.

2. Rockwell hardness is suitable for metals with high hardness, such as various alloy steel after heat treatment, and requires high surface flatness. Vickers hardness is suitable for accurately measuring the hardness of the micro-area. It is usually used to detect the effective hardened layer after metal carburization. The test surface flatness is required to be very high. It must be a polished surface.

Differences Between Rockwell Hardness and Vickers Hardness

What is Rockwell Hardness

What is Vickers Hardness

Differences Between Rockwell Hardness and Vickers Hardness

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