Brinell hardness method

Hardness represents the resistance of wood to indentation and marring. In order to measure the hardness of wood samples, the Brinell hardness method was applied. In this... 

Spraying conditions make hardness values so variable that unless they are accurately known no comparisons are possible. Brinell hardness figures for sprayed molybdenum vary from 350 when produced with a reducing flame to 725 with an oxidising flame, and while a thick sprayed deposit of 0-8% carbon steel can give a figure of 330, the hardness of a particle obtained by micro hardness methods will be about 550. 

A further development of static methods of hardness testing was a method devised by Brinell (1900), which consisted of driving a steel ball into the mineral to be tested for hardness under a pressure of 29.4 kN for about 30 seconds. Brinell hardness is defined as the ratio of load to surface of round indentation. The method has found wide use in engineering—for metals it is excellent, but in mineralogy it has proved unsatisfactory because of the high brittleness of most minerals and their non-deformability under the action of the steel ball. The ever wider application of Brinell s method and of a similar method developed by Janko in hardness determination of wood (Krzysik, 1974) should be noted. They are most useful in testing hard wood-base materials, such as compressed wood. 

Brinell method. The measurement is made by driving a calibrated hardened steel ball of diameter D into a flat and smooth sample under variable pressure P, perpendicular to the surface, and then measuring the diameter of the indentation d left on the surface (CMEA ST. 468-77 ISO R 79-68). Brinell hardness HB is the ratio of pressure P to area S of a spherical cup-shaped indentation... 

The Vickers method consists of replacing the steel ball in the Brinell hardness tester by a tetrahedral diamond pyramid with a dihedral angle 2y = 136 + 0.5° (Fig. 4.3.3, Table 4.3.1). Measurement involves applying the following loads to the pyramid as required 9.8, 19.6, 24.5, 29.4, 49, 98, 196, 291, 490 or 980 N and in measuring the diagonal of the indent obtained. Vickers hardness is the ratio of load P to lateral surface of indent... 

Fig. 4.5.4. Dependence of progress in drilling rocks on their hardness determined by Shore s and Brinell s methods. According to data of Mueller (1963), supplemented by Winkler (1973).

The hardness methods traditionally used in the abrasive industry are Brinell, Rockwell, Vickers and Mackensen-Zeiss (Table 5.8). Their useful range follows from the grain size used in the product and the bond force of the structure (binder volume) (Fig. 9.2). 

BRINELL HARDNESS TEST. The standard method of measuring the hardness of metals. The smooth surface of the metal is dented by a steel hall under force. The standard load and time are 500 kg for 60 seconds for soft metals and 3000 kg for 30 seconds for steel and other hard metals. The size (diameter) of the resulting dent is measured, and the hardness determined from a chart or formula. 

The hardness number is usually combined with the name of the method used, to indicate how the value was obtained. The commonly used tests are the Brinell, Rockwell, and Vickers hardness tests. The results of these tests are presented as the HB or Brinell hardness number, or the HV, and so on. 

Hardness The resistance of a plastic material to compression and indentation. Among the most important methods of testing this property are Brinell hardness, Rockwell hardness and Shore hardness. 

In this test a steel ball is forced against the flat surface of the specimen. The standard method (ASTM, 1978) uses a 10-mm ball and a force of 29.42 kN. The Brinell hardness value is equal to the applied force divided by the area of the indentation ... 

There are two types of hardness test static tests that involve the formation of a permanent indentation on the surface of the test material and dynamic tests in which a pendulum is allowed to strike the test material from a known distance. Vickers and Brinell tests, two examples of static methods, are the most commonly used methods for determining the hardness of pharmaceutical materials. In the Brinell test, a steel ball of diameter D is pressed on to the surface of the material, and a load F is applied for 30 sec and then removed. The diameter dj of the indentation produced is measured, and the Brinell Hardness Number (BHN) calculated by... 

BS EN 10007-1, Metallic materials—Brinell hardness test, Part 1 Test method. 1995. 

ASTM ElO. Test method for Brinell hardness of metallic materials. 1997. 

Brunauer-Emmett-Teller (method) billion electronvolt Brinell hardness number biot... 

Rockwell s hardness test works in a similar way to Brinell s hardness test, i.e., it uses the depth of penetration. Contrary to Brinell s method, however, it measures the penetration of a sphere while still under a load, and then... 

The methods which have been developed to determine hardness vary in indentor geometry and definition of the contact area. In Brinell s method, a hard sphere of diameter D is indented into the softer sample, and the Brinell hardness is calculated from the diameter of the circular indent which is left in the surface after removing the load ... 

For hardness determination, different methods are possible scratching the surface, penetration of an indenter with static or dynamic loads, or rebound as a result of elastic material behavior. The methods with a penetrating indenter are the most important ones. The applied methods are distinguished, e.g., by the shape of the indenter. Brinell hardness is determined by a ball-shaped indenter, while Vickers hardness applies a pyramid-shaped one. After the indenting test with a certain load, the surface area of the indentation is measured which delivers a value for material hardness. Determination of Rockwell hardness uses the depth of the indentation instead of the surface area (Bargel and Schulze 1988). Independent of the method, the so-called surface hardness... 

In Brinell s method, a small steel sphere is pressed into the test body with a certain force. The depth of penetration, i.e., the retained plastic deformation, is measured. The measurement is only carried out, therefore, after the load is removed. The Brinell hardness test is especially suitable for hardness tests on metals, where the measurements are made above the flow limit in the plastic region. 

Rockwell s hardness test works in a similar way to Brinell s hardness test, i.e., it uses the depth of penetration. Contrary to Brinell s method, however, it measures the penetration of a sphere while still under a load, and then measures the remaining elastic deformation. For this reason, the Rockwell method always gives lower degrees of hardness than the Brinell method. In addition, the degrees of hardness according to the Rockwell method are not measured in physical units, but in scale numbers of 0-120. Steel balls are used with soft materials, and diamond points with hard ones. The Vicker s hardness test uses a diamond pyramid. A modified Rockwell method is used for plastics. It should be noted that, with the Rockwell hardness thus determined, the plastic deformation contribution increases only gradually, because of creep. With metals, on the other hand, the deformation is always plastic, and therefore, also independent of time. Plastics, therefore, exhibit a relatively high Rockwell hardness compared to metals. 

The resistance to compression and surface indentation, usually measured by the depth of penetration of a blunt point under a given load using a particular instrument according to a prescribed procedure. Among the most important methods of testing are Barcol hardness, Brinell hardness, Knoop hardness, Mohs hardness, Rockwell hardness, and Shore hardness. 

Indentation Hardness. The values of hardness obtained by using one of the variety of test methods in which a hard probe or indenter is pressed into the surface to be tested. See vickers, KNOOP, BRiNELL hardness. 

ASTM Standard ElO, Standard Test Method for Brinell Hardness of Metallic Materials. ... 

Other methods of determining the hardness of a material include a variety of "penetration" tests that yield hardness values measured in scales known as the Brinell, Rockwell (B or C), and scleroscope scales. These scales provide reliable hardness values for most materials, including ceramics, glass, metals and alloys, and wood (see Table 21). Unfortunately, as can be seen in the table, the various tests provide somewhat different hardness values for the same materials. 

Of the static methods of hardness measurement, based on point measurement of deformations, those developed by Brinell, Rockwell and Vickers are now in use. 

Of the methods discussed above, the Brinell method is particularly useful in hardness determination of metals and soft materials of heterogeneous structure, but its drawback is that it leaves distinct postmeasurement deformation and the measurement of indent diameter and depth is difficult. 

Mackensen-Zeiss blower method, 39,101 Martens sclerometer, 48, 49 McGee s method, 92 Mean Mohs-Mackensen hardness, 106 Method, Blondel s 92 Bohme s disc, 90 Brinell, 36, 58 Davidenkov scratch point, 50 Davidenkov s, 50 dry friction without balls, 92 Harvey s 92... 

With the rapid advances now observed in hardness test methods (Vickers, Knoop, Grodzinski, Berkovich and Hanneman diamond indenters or Brinell and Rockwell hardness testers, etc.), the 10-degree Mohs scale poses a number of problems owing to the low distinction of hardness... 

A separate group of methods of limited usefulness in regard to brittle materials, making use of impact action with an indenter or steel ball, with registration of elastic rebound of a hammer or beater from the sample, consists of measurements with the Shore scleroscope, the duroscope and several other testers based on this principle, where the results come close to those obtained by the Brinell method. Working on the same principle is also the impact hardness tester, in which the depth of the indent or scratch made by a diamond indenter is measured. 

The Vickers method is applicable to both hard and soft materials, plastic and brittle, combining the merits of Brinell and Rockwell methods. A very important advantage is the ease of measurement and its wide range, 9.8-980 N for macromeasurement and 0.98 mN for micromeasurement. 

In spite of the universal character of the Vickers hardness tester, all three methods are used equivalently, as required. An example is a portable, battery-fed device with interchangeable Vickers, Brinell and Rockwell indenters resting on a piezoelectric crystal plate manufactured by Engineering and Scientific Equipment Ltd. (Fig. 4.3.10, Table 4.3.4). With this outfit, measurements can be carried out conforming to techniques recommended by, national and international standards (BS, ASTM, DIN, AFNOR). 

One of the most popular techniques used for determining the hardness of a material is the Mohs scale that consists of a qualitative but an arbitrary hardness index scheme ranging from extremely soft materials (value of 1 Moh) to very hard materials such as diamond (10 Moh). Other techniques that are often employed for measuring hardness of substances are developed by Rockwell [72], Brinell [72], Knoop, and Vickers [73]. Over the years, more quantitative methods such as nanoindentation [74] have been developed. This technique applies a small and a controllable load on to the substrate with a probe. The depth of penetration along with a known geometry of the probe provides an indirect way to measure the area of contact at full penetration, which is then used to determine the hardness. The hardness is determined by the ratio of the total force to the contact area. Table 7.2 lists the bulk hardness of different materials, metal films, and abrasive particles, in both Moh and microhardness scales [75]. 

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