Metal hardness measurements were first defined by Reoum's hardness: 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. Generally, the higher the hardness, the better the wear resistance.
Overview Overview: A hardness tester is an instrument that measures the hardness of an object.
Hardness tester classification:
First, according to the degree of complexity: simple hardness meter, complex hardness meter
Second, according to the measured hardness unit: Rockwell hardness tester, Vickers hardness tester, micro hardness tester, Brinell hardness tester, Shore hardness tester, Barcol hardness tester, Leeb hardness tester, Webster hardness tester, Shore Hardness tester, Blowwell hardness
Third, according to the mode of use: portable hardness tester, benchtop hardness tester
Hardness tester use:
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 Brinell hardness measurement of workpieces with higher hardness
The Leeb hardness tester is a portable hardness tester for hardness measurement that is not suitable for disassembly or for larger products.
Shore hardness tester for the measurement of Shore hardness of rubber products
Webster hardness tester for measuring the Vickers hardness of aluminum alloy products
Barcol hardness tester for measurement of Barcol hardness value of glass fiber reinforced plastic products
Universal hardness tester for hardness measurement under various hardness scales
Microhardness tester is a kind of Vickers hardness tester for measuring Vickers hardness of very thin workpieces.
Shore hardness tester for determining Shore hardness values ​​of ferrous and non-ferrous metals
The hardness of the Brookfield hardness tester for ferrous metals, non-ferrous metals, hard alloys, carburized layers and chemically treated layers
Hardness regulations: HS<100, HB<500, HRC<70, HV<1300, HRA (80~88), HRB (85~95), HRC (20~70)
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. Generally, 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.
principle
Hardness Tester
There are many types of hardness testers, the most commonly used Rockwell, Brinell, Vickers and microhardness test methods. Rockwell hardness measurement is one of the most commonly used hardness test methods. It is expressed by the indentation (diamond cone or hardened steel ball) under the load (including preload and main load), and the plastic deformation concentration of the material pressed into it. Generally, the greater the depth of the material being pressed, the softer the material; the smaller the concentration of the press-in, the harder the material. Indicates the measurement principle of Rockwell hardness. Brinell hardness test method 2, Brinell hardness measurement principle Select a de facto load P, press the diameter D hardened steel ball into the surface of the test piece and keep it for a certain time, then unload the load, measure the steel ball in the sample The indentation diameter d of the surface is calculated, the indentation area is calculated, and the ratio of the load P to the indentation area is calculated. The hardness represented by this ratio is the Brinell hardness.
Air Cushion Primer,Mineral Makeup Primer,Makeup Base Primer,Oil Control Makeup Primer
Guangzhou believe cosmetics co.,ltd , https://www.believecosmetics2010.com