Hardness tester is a kind of hardness testing instrument. The metal hardness measurement was first defined by Raoul, which represents the ability of materials to resist hard objects pressing into their surfaces. It is one of the important performance indexes of metal materials. Generally, the higher the hardness, the better the wear resistance.
Hardness test is the most simple and easy test method in mechanical property test. In order to replace some mechanical property tests with hardness tests, a more accurate conversion relationship between hardness and strength is needed in production.
1. Leeb hardness is designed based on the latest Leeb hardness testing principle and the most advanced microprocessor technology.
2. Brinell hardness (HB) Press a hardened steel ball of a certain size (generally 10mm in diameter) into the material surface with a certain load (generally 3000kg) for a period of time. After unloading, the ratio of the load to the indentation area is the Brinell hardness value (HB), and the unit is kilogram force/mm2 (N/mm2).
3. Rockwell hardness (HR) When HB>450 or the sample is too small, Rockwell hardness measurement shall be used instead of Brinell hardness test. It uses a diamond cone with a vertex angle of 120 ° or a steel ball with a diameter of 1.59 and 3.18 mm to press it into the surface of the tested material under a certain load, and the hardness of the material is calculated from the depth of the indentation. According to the different hardness of test materials, there are three different situations
HRA: the hardness obtained by using 60kg load and diamond cone indenter, used for materials with extremely high hardness (such as cemented carbide).
HRB: hardness obtained by using 100kg load and 1.58mm diameter hardened steel ball, used for materials with low hardness (such as annealed steel, cast iron, etc.).
HRC: the hardness obtained by using a 150kg load and a diamond cone indenter, used for materials with high hardness (such as quenched steel).
4. Vickers hardness (HV) is pressed into the material surface with a load within 120kg and a diamond square cone indenter with a top angle of 136 °. The Vickers hardness value (HV) is obtained by dividing the load value by the surface area of the material indentation dent.
5 Knoop hardness (HK)
It is applicable to the hardness test of high hardness materials (generally the hardness measurement above HV1000).
6. Shore hardness tester
7. Vickers hardness tester (HW)
It is applicable to the measurement of Vickers hardness of aluminum alloy products.
8 Gypsum hardness tester
It is applicable to the hardness measurement of building gypsum. Put the steel ball on the test piece, measure the depth of the ball mark under the action of fixed load, and calculate the gypsum hardness of the test piece.
The above hardness is only commonly used. In addition, there are Shore (HS) hardness, Shore (HS) hardness, Babbitt hardness, Mohs hardness, etc. Practice has proved that there is an approximate corresponding relationship between hardness values and strength values of metal materials. Because the hardness value is determined by the initial plastic deformation resistance and the continuous plastic deformation resistance, the higher the strength of the material, the higher the plastic deformation resistance, and the higher the hardness value.
Post time: Nov-17-2022