Hardness is the ability of a material to resist local deformation, especially plastic deformation, indentation, or scratching. It is a measure of the hardness and softness of a material. Vickers hardness, brinell hardness, rockwell hardness table to share with you, quickly hide it!

HV = HB = HRC hardness control table

Data in this table are from Din 50150.

The hardness of a metal material is its ability to resist local deformation, especially plastic deformation, indentation, or scratching. It is a measure of the hardness and softness of a material. According to the different test methods, hardness is divided into three types. 1 scratch hardness. It is mainly used to compare the hardness and softness of different minerals. The method is to select a rod with one end hard and the other end soft. Qualitatively speaking, hard objects make long scratches, soft objects make short scratches. 2 indentation hardness. It is mainly used for metal materials by pressing the specified indenter into the tested material with a certain load, and comparing the hardness of the tested material with the local plastic deformation of the material surface. There are many kinds of indentation hardness, such as brinell hardness, rockwell hardness, vickers hardness and micro-hardness, because of the difference of Indenter, load and load duration. 3 bounce hardness. The utility model is mainly used for a metal material by making a specially made small hammer drop freely from a certain height to impact a sample of the material to be tested, the hardness of the material is determined by the amount of strain energy stored (and then released) by the specimen during impact (measured by the rebound height of the Hammer) . The most common brinell hardness, rockwell hardness and vickers hardness of metallic materials are indentation hardness, which indicates the ability of the surface of the material to resist the plastic deformation caused by the pressing of another object, the hardness value represents the elastic deformation function of the metal. Brinell Hardness Brinell Hardness with a diameter of d quenched steel ball or hard alloy ball as the indenter, with the corresponding test force F pressed into the surface of the specimen, after the specified holding time, remove the test force, get a diameter of d indentation. The brinell hardness value is obtained by dividing the indentation surface area by the experimental force, and is denoted by HBS or HBW.

The difference between HBS and HBW is the pressure head. HBS states that the indenter is a hardened steel ball used to determine materials with a brinell hardness of less than 450, such as mild steel, gray iron, and Non-ferrous metal. HBW indicates that the indenter is a hard alloy used for materials with a brinell hardness value below 650. In the same test block, when other conditions are identical, the HBW value is higher than the HBS value, and there is no quantitative rule. Since 2003, the international standard has been adopted in our country, the steel ball indenter has been eliminated, and the hard alloy ball indenter has been used completely. Therefore, HBS was discontinued and all HBW was used as the brinell hardness symbol. Many Times brinell hardness is expressed only in HB, meaning HBW. But HBS still sees something in the literature. Brinell hardness measurement is suitable for cast iron, non-ferrous Alloy, all kinds of annealed and quenched and tempered steels. It is not suitable to measure samples or workpieces that are too hard, too small, too thin and the surface of which does not allow large indentation. Rockwell Hardness Rockwell Hardness with 120 ° diamond cone or ?1.588 mm and ?3.176 mm quenched steel balls as indenter and load. The specimens are pressed under initial load of 10 KGF and total load of 60,100 or 150 KGF force (I. E. Initial load plus main load) , the hardness is expressed by the difference between the indentation depth when the main load is removed but the main load is retained and the indentation depth under initial load.

The Rockwell scale uses three test forces and three indenters in nine combinations corresponding to the nine scales of Rockwell hardness. The use of these nine gauges covers almost all commonly used metal materials. There are three kinds of HRA, HRB and HRC in common use, among which HRC is the most widely used.

The HRC scale is used in the range of 20 ~ 70 HRC. When the hardness value is less than 20HRC, because the cone part of the INDENTER is pressed too much, the sensitivity drops, then the HRB scale should be used; when the hardness of the sample is more than 67HRC, the pressure on the indenter tip is too large, the diamond is easy to be damaged, and the indenter life will be greatly shortened, therefore, HRA ruler should be used instead. The Rockwell scale is easy to operate, fast, small indentation, can test the finished surface and harder, thinner workpiece. Because the indentation is small, for the structure and hardness of uneven material, hardness value fluctuation, accuracy is not as high as brinell hardness. Rockwell hardness is used to determine the hardness of steel, Non-ferrous metal, carbide, etc. . Vickers Hardness the Vickers Hardness principle is similar to that of brinell Hardness. The diamond quadrangular cone indenter with a relative angle of 136 ° is used to press the specified test force F into the surface of the material, to remove the test force after holding the specified time, and to express the hardness value by the average pressure per unit surface area of the positive quadrangular cone indenter, the symbol is HV.

Vickers hardness measurement range is large, can be measured hardness of 10 ~ 1000HV range of materials, small indentation, generally used to measure thin materials and carburizing, nitriding and other surface hardening layer. Leeb Hardness with a certain mass of Tungsten Carbide ball-head impact under a certain force on the surface of the specimen, and then rebound. Because of the different hardness of the material, the rebound speed after impact is also different. Permanent magnetic material is installed on the impact device. When the impact body moves up and down, the outer coil will sense the electromagnetic signal proportional to the velocity. The hardness sensor is as small as a pen. It can be operated directly by hand. It can be used to measure the hardness of large, heavy or complicated workpieces. Another advantage of the riesling hardness test is that it can be used as a non-destructive test because of its low damage to the surface of the product.

Source: The world of metallic materials

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