The hardness tester is an instrument for measuring the hardness of an object, and can be classified into a simple hardness tester and a complex hardness tester according to the degree of complexity. According to the measured hardness units are classified as: Rockwell hardness tester Vickers hardness tester Micro hardness tester Brinell hardness tester Shore hardness tester Barcol hardness tester Richter hardness tester Webster hardness tester. The hardness tester is an instrument for measuring the hardness of an object, and can be classified into a simple hardness tester and a complex hardness tester according to the degree of complexity. According to the measured hardness units are classified as: Rockwell hardness tester Vickers hardness tester Micro hardness tester Brinell hardness tester Shore hardness tester Barcol hardness tester Richter hardness tester Webster hardness tester.
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Rockwell hardness tester Vickers hardness tester Brinell hardness tester Richter hardness tester Shore hardness tester Webster hardness tester Barcol hardness tester Hardness tester Micro hardness tester Other hardness tester Standard hardness block can be divided into portable hardness Meter and benchtop hardness tester.
Rockwell hardness tester for Rockwell hardness measurement of workpieces such as cast iron. Vickers hardness tester for Vickers hardness measurement of thinner workpieces. Brinell hardness tester for high hardness workpieces. Brinell hardness value measurement. It is a portable hardness tester for hardness measurement of unsuitable or larger products. Shore hardness tester for rubber products. Shore hardness test. Wechsler hardness tester for aluminum alloy products. For the FRP product, the Barcol hardness value measurement universal hardness tester is used for the hardness value measurement under a variety of hardness scales. One of the Vickers hardness testers for the micro hardness tester, the Vickers hardness value measurement for a very thin workpiece. The hardness tester is used to determine the Shore hardness hardness of ferrous and non-ferrous metals:
HS HB HRC HV (80~88) HRA, (85~95) HRB, (20~70) HRC
A, B, and C in HRA, HRB, HRC, etc. in Rockwell hardness are three different standards, called scale A, scale B, and scale C.
The Rockwell hardness test is one of several common indentation hardness tests used today. The initial pressure of all three scales is 98.07N (10kgf), and the hardness value is calculated according to the indentation depth. The ruler A uses a diamond indenter and is then pressurized to 588.4 N (60 kgf); the ruler B uses a steel ball with a diameter of 1.588 mm (1/16 inch) as the indenter, and then pressurizes to 980.7 N (combined) 100kgf); while the scale C uses the same diamond as the scale A as the indenter, but the force after pressurization is 1471N (150kgf). Therefore, scale B is suitable for relatively soft materials, while scale C is suitable for harder materials.
Practice has proved that there is an approximate relationship between the hardness values ​​and the strength values ​​of various hardness values ​​of metal materials. Because the hardness value is determined by the initial plastic deformation resistance and the continued plastic deformation resistance, the higher the strength of the material, the higher the plastic deformation resistance and the higher the hardness value. However, the conversion relationship of various materials is not consistent.
Hardness indicates the ability of a material to resist the intrusion of a hard object into its surface. It is one of the important performance indicators of metallic materials. Jinjitong suggests that the higher the hardness, the better the wear resistance. Commonly used hardness indexes are Brinell hardness, Rockwell hardness and Vickers hardness.
1. Brinell hardness (HB)
Press a hardened steel ball of a certain size (usually 10mm in diameter) onto the surface of the material with a certain load (usually 3000kg) for a period of time. After the load is removed, the ratio of the load to the area of ​​the indentation is the Brinell hardness value. HB), in kilograms force / mm2 (N / mm2).
2. Rockwell hardness (HR)
When HB>450 or the sample is too small, the Brinell hardness test cannot be used instead of the Rockwell hardness measurement. It uses a diamond cone with a apex angle of 120° or a steel ball with a diameter of 1.59 and 3.18 mm, and is pressed into the surface of the material to be tested under a certain load, and the hardness of the material is determined from the depth of the indentation. According to the hardness of the test material, it is represented by three different scales:
HRA: is the hardness obtained by using a 60kg load and a diamond indenter for materials with extremely high hardness (such as cemented carbide).
HRB: It is a hardened steel ball with a load of 100kg and a diameter of 1.58mm. The hardness is used for materials with lower hardness (such as annealed steel, cast iron, etc.).
HRC: is the hardness obtained by using a 150kg load and a diamond indenter for materials with high hardness (such as hardened steel).
3 Vickers hardness (HV)
The surface of the material is pressed into the surface of the material with a load of 120 kg or less and a diamond square cone presser with a apex angle of 136°. The surface area of ​​the material indentation pit is divided by the load value, which is the Vickers hardness HV value (kgf/mm2).
HK=139.54?P/L2. Where: HK-Knoop hardness, Mpa; P-load, kg; L-pit diagonal length, mm. Vickers hardness is used in China and Europe, and Knoop hardness is used in the United States. Megapascal (MPa) is the legal unit of measurement for microhardness, and kg/mm2 is the previously used hardness calculation unit. The conversion formula between them is 1kg/mm2=9.80665Mpa.
4. Webster hardness tester (HW)
Principle: HW=20-L/0.01, where L is the depth of the pressed sample, suitable for fast and convenient non-destructive testing and quality control of aluminum alloy hardness.
The test is quick and easy, one card can be used, the hardness value can be read directly, in line with the Chinese non-ferrous standard YS/T420 and the American standard ASTM B647, which is one of the two instruments recommended by the standard YS/T420.
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