Metal hardness measurement was first defined by Ray Ommel's definition of hardness: It indicates the ability of a material to resist the intrusion of a hard object onto its surface. It is one of the important performance indicators of metal materials. The higher the hardness in general, the better the abrasion resistance.
table of Contents
Commonly used hardness classification
Hardness test is the simplest and most convenient test method in mechanical performance test. In order to be able to replace certain mechanical properties tests with hardness tests, a more accurate conversion of hardness and strength is required for production.
1. Leeb hardness (Dietmar Leeb) Leeb hardness is designed using advanced microprocessor technology based on the latest Leeb hardness testing theory.
2. Brinell Hardness ( HB ) Hardened steel balls of a certain size (typically 10mm in diameter ) are pressed into the surface of the material at a given load (generally 3000kg ) and held for a period of time. After loading, the ratio of the load to the indented area , which is the Brinell hardness value ( HB ) in kilograms force /mm2 (N/mm2 ).
3. Rockwell Hardness ( HR ) When HB>450 or when the specimen is too small, the Brinell hardness test cannot be used instead. It uses a diamond cone with a vertex angle of 120° or steel balls with a diameter of 1.59 and 3.18 mm to press the surface of the material under test under a certain load. The hardness of the material is obtained from the depth of the indentation. According to the hardness of the test material, divided into three different situations
HRA : Hardness obtained with a 60kg load and a diamond cone press, used for extremely hard materials (such as hard alloys, etc.).
HRB : Hardened steel ball with a load of 100kg and a diameter of 1.58mm . Hardness determined for low hardness materials (annealed steel, cast iron, etc.).
HRC : It is the hardness obtained with a 150kg load and a diamond cone press. It is used for materials with high hardness (such as quenched steel, etc.).
4. Vickers hardness ( HV ) is pressed into the surface of the material by a diamond square cone presser with a load of 120 kg or less and a vertex angle of 136° . The load value is divided by the surface area of the material indentation pit, which is the Vickers hardness value. ( HV ).
5 Knoop Hardness (HK)
Suitable for hardness testing of high hardness materials (general hardness measurement above HV1000 hardness).
6. There are Shore Hardness Tester
7. Vickers Hardness Tester ( HW )
Suitable for the measurement of Vickers hardness value of aluminum alloy products .
8 plaster hardness tester
Applicable to the measurement of the hardness of building plaster. The steel ball is placed on the test piece. The depth of the ball mark under the action of the fixed load is measured. The gypsum hardness of the test piece is calculated.
The above hardness is only a few commonly used, in addition to Shore ( HS ) hardness, Shore ( HS ) hardness, Barcol hardness , Mohs hardness . Practice has shown that there is an approximate correlation between hardness values and strength values between various hardness values of metallic materials. Because the hardness value is determined by the resistance to initial plastic deformation and the resistance to continued plastic deformation, the higher the strength of the material, the higher the resistance to plastic deformation and the higher the hardness value.
Hardness tester classification
According to the principle can be divided into: Leeb Hardness Tester , Rockwell Hardness Tester , Brinell Hardness Tester , Shore hardness tester , Shore hardness tester , Barcol hardness tester , Micro Hardness Tester, Mohs hardness tester, Vickers hardness tester Wait.
According to the measurement object is divided into: fruit hardness , cement hardness tester.
Copyright © 2019 JINAN KASON TESTING EQUIPMENT CO., LTD. All rights reserved.