Introduction of Rockwell hardness
Rockwell hardness is an index to determine the hardness value by the depth of indentation plastic deformation, with 0.002 mm as a hardness unit, expressed as HR. 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 3 scales commonly used, and their applications cover almost all commonly used metal materials.
The three scales are A, B, and C, namely HRA, HRB, and HRC. According to the hardness of the experimental material, scales with different hardness ranges are selected to represent:
- HRA is the hardness obtained by using a 60Kg load and a diamond cone indenter, and is used for materials with higher hardness. For example: steel sheet, cemented carbide.
- HRB is the hardness obtained by using a 100Kg load and a hardened steel ball with a diameter of 1.5875mm, which is used for materials with lower hardness. For example: mild steel, non-ferrous metals, annealed steel, etc.
- HRC is the hardness obtained by using 150Kg load and diamond cone indenter, which is used for materials with higher hardness. For example: hardened steel, cast iron, etc.
Introduction of Vickers hardness
Vickers hardness represents a standard of material hardness. It was first proposed by British scientist Vickers and expressed as HV. Vickers hardness test is mainly used for small load Vickers hardness test in material research and scientific testing. hardness, hardness near the cutting edge, hardness of dental materials, etc. Since the test force is small and the indentation is small, the appearance and performance of the sample are not affected.
The Vickers hardness tester has a wide measurement range and 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 latter is the test force. If the test force holding time is not the usual 10-15 seconds, the holding time should be marked after the test force value. For example: 600HV30/20 means using a test force of 30 kgf for 20 seconds to obtain a hardness value of 600.
The Difference between Rockwell Hardness and Vickers Hardness
Rockwell hardness, easy to operate, can be read directly, and the indentation is small, suitable for batch and finished product production, but multi-point testing is required to ensure accuracy. Vickers hardness tests cover a wide range of materials, from softer to superhard materials.
Rockwell hardness, suitable for metals with higher hardness, such as various alloy steels after heat treatment, which requires a higher test surface flatness. Vickers hardness is suitable for accurately measuring the hardness of micro-area. It is usually used to detect the effective hardened layer after metal carburization. The test surface is required to have a very high flatness and must be a polished surface.
For more information on this source, please visit TITLTEST.COM If you need to know more details about the instruments or equipments mentioned, please contact support@titltest.com