Brinell Hardness Test 

+MaterialsScience Thank you for that answer, I was curious as to what material was being used for the indenter. Seeing as how this test has certain limitation I'm curious as to whether or not the Vickers test is seen as being more reliable. Then again, it's probably rare to have to frequently test materials above the limitations of the Brinell test.

Hello, But for non ferrous alloys like aluminium alloy hardness value measured in HB how...?

+SalveMonesvol Main considerations are (among many others):>> Brinell: +> good for heterogeneous materials like grey cast iron (if average hardness is wanted), because the tested volume is comparatively large -> no small indentations are possible, very hard materials cannot be tested>> Vickers: +> almost all materials (except diamond) can be tested, test region can be extremely small and just one grain may be tested -> large indentations are not possible, not good for heterogeneous materials, if average hardness is wanted>> HRC: +> easy to automate (very important) -> no very small indentations possible, less variable

MaterialsScience2000 Thank you very much!

Answer to "I would like to know what are the parameters to consider for choosing a scale Rockwell Hardness and what are the reasons for chossing these parameters.. if it's maybe depending from the material, etc??.. well your video was about the Brinell hardness test but if you can help me about the Rockwell hardness if possible..": The Rockwell hardness scales A, B, C, ... have been introduced for application at different hardness levels, for instance B for rather soft materials and C for rather hard materials. The equations, for example HRC = (0.2-e)*500, were introduced (i) originally for easy display of the hardness value on old testing machines and (ii) to get a "nice" hardness value scale of up to 100. The depth of indentation e is limited to a maximum of 0.2 mm.

@@MaterialsScience2000 may i get your WhatsApp please.

Answer to "Will the diameter of the ball be including in the testing?": Yes, it is important. The equation to calculate the spatial area of the indentation (using the measured indentation diameter) includes the ball diameter.

Answer to "Sir ,Is 250 hb is for specific load only .if yes then for different loads we have to calculate different times to find hardness. So is it a limitation of this machine or i am wrong. Sir plzz make my confusion clear.": In the Brinell hardness test different loads may be applied for one and the same material, as long as the indents in the material are reasonable (within a given range). In most cases, the results are almost identical for different loads. Twice the load normally leads to twice the surface of the ball impression - and the same hardness as a result.

Answer to "Can I know which indentor ( material ) is used in this test? Also how much hardness is desirable to test mild steel rod? ( Mean to say, how much difference in hardness is preferable between indentor and workpiece?)": This is an important point. Here we have used an indenter made from cemented carbides, and this has been standard for a long time now. The indenter has to be at least 3 times as hard as the workpiece. Since typical cemented carbide indenters have a Vickers hardness (roughly identical to Brinell hardness) of 1800 to 2000, the maximum Vickers hardness for the workpiece is around 600 HV, which is roughly equal to a Brinell hardness of 600.

Answer to "Surface area of the indentation surface, which is spherical, or the surface area of the indentation projected as a circle?" The Brinell hardness is defined as the test force (in kiloponds!) divided by the spherical indentation area (in square millimetres). The spatial area is therefore taken, not the projected area.

Answer to "Hello, can you tell me that machines are used for this test?" Do you mean "which" machines are used ...? If yes, there are many manufacturers, which you can easily find in the internet. We have a machine from "KB Prüftechnik".

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Answer to "Hi please can I use some parts of your video for my youtube video on material sciences? Thank you": I am afraid, all our videos are under the RU-vid standard license. This means, that no download/hosting/use whatsoever is allowed. But you can always set links to our videos!

+7150285 Usually, thicker metals will have a lower hardness, due to the nature of the thermal treatment. Also, an extremely thin (1/10th of a mm for egsample) can not be tested for hardness with normal methods because it it not thick enough to allow the indentation, you would be indenting the machine's support surface; I would use the old method of scratching with known hardness files.

SalveMonesvol another question, core hardness is usually harder or softer than surface hardness?

7150285 Softer. It cools slower.

Answer to "please explain the working of universal testing machine": In a few words: There is an electric motor with a spindle gear, which slowly lowers the indenter until the intended force is reached. The force is measured with a classic strain gauge load cell.

Answer to "Why are the surfaces in the tests you presented different? For example, in diamond the surface was small, but here it is large.": The diamond indenter for the Vickers hardness test is comparatively small. Consequently, the material to be tested must be fairly homogeneous and the surface roughness must be low. The ball indenter for the Brinell hardness test is comparatively large and the tested material may (to a certain extent) have a certain inhomogeneity and higher roughness. This is reflected in the surface quality of the test samples.

@@MaterialsScience2000 Thank you.

+Deepesh Mehta As a ball diameter D you may choose any that will fit the purpose (shouldn't be too large). For comparatively hard aluminium alloys the (empirical) equation F = 10*D^2 (D in mm, F in kp) will give you an initial (good) guess for the test force. Example: D = 1 mm >> F = 10*1^2 kp = 10 kp (= 98.1 N).

Answer to "how do you measure the depth of indentation?" In classical Brinell hardness testing, the depth of indentation is not measured, only in Rockwell hardness testing, for example with electromagnetic transducers.

@@MaterialsScience2000 thanks for the info!

Answer to "I'd like to know the purpose of using this machine .I m looking forward to hearing from u.": Well, to measure the hardness of a test specimen. And hardness is an interesting material property for practical applications of materials: Hardness is related to strength, to some extent to wear, to heat treatment ...

Answer to "Material used for indentor ?": The indenter is made of cemented carbide.

Answer to "What is the name of this testing machine": This is a "universal" hardness testing machine that can be used for Brinell, Vickers and Rockwell tests. The manufacturer is "KB Prüftechnik" or "Hegewald und Peschke". The actual testing machines differ from those shown in the video.

Answer to "bisa untuk test kekerasan beton?": No, concrete cannot (reasonably) be tested with the Brinell hardness test, because it is a far too brittle material.

Answer to "Don't we need to polish the surface?": In Brinell hardness testing, the depth of indentation is usually much greater than the surface roughness. Therefore, polished surface quality is usually not required. If the surface roughness is low, no preparation is required at all. Otherwise, a fine grinding preparation is sufficient.

@@MaterialsScience2000 thank you.

Answer to "What is HB? in 250 HB": HB means Hardness Brinell or hardness according to the Brinell method.