1. Rockwell hardness tester (HRC): generally used for testing materials with high hardness, such as hardness after heat treatment and hardness of various steels (including alloy steel and stainless steel). Determine the hardness index based on the depth of indentation plastic deformation. Use 0.002 millimeters as a hardness unit. When HB>450 or the sample is too small, Brinell hardness test cannot be used and Rockwell hardness measurement should be used instead. It uses a diamond cone with a vertex angle of 120 ° or steel balls with diameters of 1.59 and 3.18mm to press into the surface of the tested material under a certain load, and the hardness of the material is determined by the depth of the indentation.
According to the different hardness of the test materials, there are three different scales to represent them: HRA, HRB, and HRB. Rockwell hardness tester (HRC) includes manual Rockwell hardness tester, electric Rockwell hardness tester, digital Rockwell hardness tester, portable Rockwell hardness tester, etc.
2 . Vickers hardness tester (HV): used to measure the hardness of ferrous metals, non-ferrous metals, hard alloys (such as aluminum alloys), and surface carburizing and nitriding layers, expressed in HV. For materials with thin surface layers and low hardness, a low load Vickers hardness tester should be used. This type of hardness tester is equipped with a microscope (some manufacturers refer to it as a microhardness tester) to observe the indentation made, and some are also equipped with a programming calculator to quickly and accurately calculate the hardness value. There is also a type called micro Vickers hardness tester, with a small test force of only 10 grams force (10gf).
3. Brinell hardness tester (HB): Brinell hardness (HB) is generally used when materials are relatively soft, such as non-ferrous metals, steel before or after heat treatment, untempered steel, cast iron, and soft bearing alloy materials, represented by HBW. Cloth hardness is a test load of a certain size, in which a quenched steel ball or hard alloy ball of a certain diameter is pressed into the surface of the tested metal, held for a specified time, and then unloaded to measure the diameter of the indentation on the tested surface. The Brinell hardness value is the quotient obtained by dividing the load by the surface area of the indentation sphere. Generally, a quenched steel ball of a certain size (usually 10mm in diameter) is pressed onto the surface of a material with a certain load (usually 3000kg), held for a period of time, and after unloading, the ratio of the load to the indentation area is the Brinell hardness value (HB), measured in kilogram force/mm2 (N/mm2).
In addition to the general digital Brinell hardness tester, there are also portable Brinell hardness testers, hammer type Brinell hardness testers, and door type Brinell hardness testers.
4. Blowe hardness tester: a hardness tester that can test three types of hardness: Brinell, Rockwell, and Vickers. More suitable for development and research purposes.
5. Shore hardness tester (HS, also known as Shore hardness tester): There are not many standards in this area in China, only HA and HD are available. The former is a hardness parameter for softer rubber, while the latter is a hardness parameter for harder rubber or plastic. It should be pointed out that some plastics have high hardness, such as "Saigang" (which can be made into wear-resistant parts such as gears), and are not suitable for measuring hardness with a Shore hardness tester.
6. Ultrasonic hardness tester: The sensor probe is in contact with the measured object, and under uniform contact pressure, the resonant frequency of the sensor changes with the indentation depth (i.e. hardness). The purpose of measuring hardness is achieved by measuring the change in this frequency. This method causes minimal damage to the measured object and is a non-destructive measurement. At the same time, the signal pickup method of electromechanical conversion is used. Based on the principle of ultrasonic metrology, an intelligent digital ultrasonic hardness tester with high accuracy and strong functionality has been developed.
7. Leeb hardness tester:A smaller hardness tester that can convert various hardness values. Mainly used for testing metal materials, especially for larger workpieces. Due to the variety of impact devices available, the selection should be based on specific needs when making a purchase. It is mainly used for testing molds, as it is difficult to test large molds with a typical Rockwell hardness tester. The data obtained from testing with a Rockwell hardness tester can be converted.