Brinell testing

Test pieces for Brinell testing must have two parallel sides and be reasonably smooth for proper support on the anvil of the test machine. Minimum sample thickness must be 10 times indentation depth. Successive indentations must not be closer than three indentation diameters to one another or to the edge of the test piece. 

Thus the Brinell test in its original manifestation is a laboratory test in which cut pieces are brought to it for testing. The lack of portabiUty spawned several modifications to achieve that property. 

The Brinell test range is limited, by the capabUity of the hardened steel baU indenters used, to HBN 444. This range can be extended upward to HBN 500 by using special cold work-hardened steel baUs and to as high as HBN 627 by using special tungsten carbide bads. 

Standard practice for Brinell testing is to measure the diameter of each indentation twice and average the measurement before entering the tables to determine HBN. The same averaging principle is appHed on nonflat (curved) surfaces which yield an ediptical, not a round, indentation. 

Brinell Tests of Steel Products Comparison Hardness Tester Practice Rockwell Test on Cemented Carbides Rockwell Test for Sintered Materials Knoop Test for Electrodeposited Coatings Webster Hardness Gauge Barcol Test of Aluminum Alloys... 

Vickers Hardness. The Vickers or diamond pyramid hardness (DPH) developed in 1924 was an improvement over the Brinell test. The Vickers test used a pyramidal diamond as the indenter. This permitted the hardness testing of much harder materials, and the constant 136° angle of the indenter eliminated the problem of variable indentation shape encountered using spherical indenters (1). 

Brinellharte, /. Brinell hardness, brlnellieren, t.t, test with the Brinell machine. Brinell-probe, /. Brinell test or sample, -zahl, /. Brinell number. 

The Brinell test uses an indentor of 10 mm diameter hardened steel ball, and applies a load which is usually 3000 kg. The Brinell hardness number (BHN) is defined as the load, F (kilogrammes), divided by the surface area of the indentation. The expression given below describes the definition. 

Indentation hardness is a very common determination in materials testing. In this test a very hard indenter (a hard steel sphere in the Brinell test, a diamond pyramid in the Vickers test) is pressed under a load into the surface of the material. 

In the Brinell test (Brinell, 1900 Meyer, 1908) the indenter consists of a hard steel ball, though in examining very hard metals the spherical indenter may be made of tungsten carbide or even of diamond. Another type of indenter which has been widely used is the conical or pyramidal indenter as used in the Ludwik (1908) and Vickers (see Smith Sandland (1925)) hardness tests, respectively. These indenters are now usually made of diamond. The hardness behaviour is different from that observed with spherical indenters. Other types of indenters have, at various times, been described, but they are not in wide use and do not involve new principles. 

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... 

There are four major indentation hardness tests, which differ from each other in the shape of the indenter (Figure 10.23). The first of these, described in 1900, was the Brinell test, using a 10 mm steel ball indenter (Figure 10.23a), giving the Brinell hardness number, BHN. This was suitable only for metals softer than steel. In 1920 Rockwell developed a number of tests, including the B, E, F and G scales, in which the indenter is steel, and the A, C and D scales, using a conical diamond indenter with a spherical tip (Figures 10.23b and 10.23c). In the Rockwell test the difference in size between the... 

ISO 6506. Metallic materials—Flardness test—Brinell test. 1981. 

FIGURE 3.42 Indentation hardness tests, (a) Brinell test, (b) Vickers test, (c) Knoop test. 

The Vickers hardness test differs from the Brinell test in that the indentor is a diamond (square-based) pyramid (Figure 3.42) having an apex angle of 136°. If the average diagonal of the indent is d, the hardness number is calculated from... 

As in the Brinell test, tables are available to convert the average diagonal into Vickers number. 

One common hardness test is the Brinell test, in which a hardened steel ball is used as the indenter. The Brinell Hardness Number (BHN) is the applied force F divided by the surface area of the indentation, i.e.. 

Hardness refers to the resistance of steel to indentation. The three important methods to determine the hardness are (1) the Brinell test, (2) the Vickers test, and (3) the Rockwell test. All these methods use the same basic principle wherein a ball or a pointed indenter is forced onto the material surface under a given load and the area of indentation thus created is measured. The Brinell test uses a 10-mm-diameter tungsten ball indenter under a load of 29,420 N. The Rockwell C hardness test uses a diamond cone indenter under a load of 1471 N. The Vickers test uses a diamond pyramid indenter, and the load varies. The greater the hardness of a material, the smaller the area of indentation. 

There are a variety of types of hardness tests, but the most popular in the case of rare earth metals seems to have been the Brinell test and the Vickers, or Diamond Pyramid Hardness (DPH) test as it is most commonly called. The DPH test is perhaps the most reliable hardness test and, in fact, should give hardness values in close agreement with the results of properly conducted Brinell and Knoop (when loads are >500 g) hardness tests. Consequently, the emphasis in this section is on DPH data, but Brinell data are also presented where they are instructive. Frequently, microhardness data are quoted in the rare earth literature. Since they are determined with a diamond pyramid indenter using lower loads than macrohardness, the author includes them with DPH values when they are in agreement with macroscopic values although it is recognized that microhardness results can be load sensitive. 

In our industry, the most common application is the Brinell test method but the following will summarize the three proeesses. 

Brinell. In the Brinell test, a hardened steel ball is forced into the specimen. The standard test uses a 10-mm ball and a force of 29.42 kN (34). The Brinell hardness HB is equal to the applied force divided by the area of the indentation ... 

This group of tests has already been referred to in order to emphasize the multifunctional nature of hardness. There are several modes depending upon whether a ball, cone, or pyramid is forced into the ceramic surface. In all cases the load per unit area of impression is given as the measure of hardness. Results here are more variable than might seem necessary because different test methods use different unit areas. For example, in the Brinell test where a small sphere is used to indent the surface the hardness is calculated from the contact area, not the area in the plane of the surface which would seem to be a more directly measured and calculated variable. Thus... 

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