Talk:Vickers hardness test

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Equation[edit]

The equation provided with the sin 1/2 136 seems to have unusual bracketing. The 136 im assuming has units of degrees, therefore would it not need to be encompassed by the sin term? thus sin (136/2) degrees? 129.78.64.106 06:53, 6 September 2006 (UTC)

Would anyone be able to find some sample Vickers hardness values for typical materials?

Added Stainless steel, Carbon steel and iron. Pity i couldnt find them with the same load value User A1 04:58, 12 September 2006 (UTC)

Update 21/12/11: Typical values are difficult to define. I tested different samples of brass (40%Zn) today that varied from 40-140 Hv. It is almost entirely dependent upon the microstructure of the material, the grain size, phases present, amount of cold work...etc. All you can really do is give a range of values but there are very few databases that will keep these. I would try CES software which is available at the majority of universities. — Preceding unsigned comment added by 101.160.172.66 (talk) 09:36, 21 December 2011 (UTC)

HV = 2017[edit]

Something seems amiss here, and maybe it is a difference in the numbers used or my confusion but.. I purchased an Aluminum Oxide Ceramic stock bar. It is harder than anything I have come across and was not of any use to me, because I ruined blades trying to cut it! But here is my problem.. It came with a slip of paper with all of the specs, Here is the part of it I'm confused about: Hardness (Vickers): Unit - HV Value - 2017 I've been told this stuff is nearly equal to a diamond in hardness. But the 2017 for a value does not coincide with the types of numbers provided here. —Preceding unsigned comment added by 75.17.209.222 (talk) 20:54, 25 October 2010 (UTC)

Chapter 22 instead of 23[edit]

Considering the index of Smithells Metals Reference Book I assume that the values mentioned are not in chapter 23 (sintered materials) but in 22 (mechanical properties of metals and alloys). I'll check this afternoon if my conclusion is right. 130.161.144.96 11:11, 22 June 2007 (UTC)

I found the values in an online database, as my library didn't have it in hard copy. If you have the book that would be a better source. Thanks User A1 13:17, 22 June 2007 (UTC)

Applicable applications[edit]

Can anybody define where Vickers hardness tester is most applicable? Is it to check sheet meatals / castings / soft meatals etc. —Preceding unsigned comment added by 222.124.137.2 (talk) 02:15, 20 October 2009 (UTC)

THe vicker's hardness test is applicable to any sufficiently ductile material that has a thickness of roughly 4 times the depth of the indent, even non-metals. It can be used for any material, however there are nuances associated with its use, as hardness can be a function of grain orientation, grain size and location within a grain (for grain sizes on par with indenter size) User A1 (talk) 03:42, 20 October 2009 (UTC)

Theoretically Speaking...[edit]

Well, you want to measure the indented surface area, not the square projection that it makes with the top surface, right? But in fact, the difference is only a matter of a proportionality constant. In other words either one could have been used as a measure of hardness, so why use the one that is more difficult? In fact, it is the square that is actually measured. Actually measuring the indented surface is not even done. It would seem more reasonable, that the originators of the Vickers test would have not bothered mentioning anything else, other than the top rectangle. To mention the surface area of the indent seems pointless, since it is proportional to it. The point of a hardness scale is the comparison of materials to each other. In other words a difference of a (multiplicative) constant divides out when comparing materials. It is said that the Vickers hardness is not a pressure, but it seems to me to be proportional to a pressure, and therefore a pressure. I mean, kilograms/area = pressure, right?? That is, the surface area of the material is pushing back a certain number of kilograms, which seems like pressure, doesn't it? Well, sometimes there is background politics behind these things. I mean it is my favorite hardness scale, but I think the originators were talking gobbly-gook. They should have divided the kg's by the surface area of the rectangle and expressed the result as Kg/mm². Such a scale would have been fully equivolent to the one they chose, and it would seem more useful. Just my three cents. —Preceding unsigned comment added by 71.198.228.109 (talk) 20:03, 10 August 2010 (UTC)

Conversion to MPa[edit]

Most WP articles eg. copper give the Vickers hardness in MPa. What does one multiply by to convert from Vickers hardness numbers to VH in MPa ? (Is it 1.0 or 0.189 ?) Rod57 (talk) 00:16, 12 February 2011 (UTC)

According to the article it's 0.189. Wizard191 (talk) 02:37, 12 February 2011 (UTC)
Rereading the article; one should multiply HV# by 9.8.. to convert to MPa. - Rod57 (talk) 02:26, 25 November 2011 (UTC)

Yield Strength conversion[edit]

The equation states that Hv/3 = yield strength, it is the other way around! yield strength = Hv*3

Can someone please change this.

SI-Unit Formula Is Wrong[edit]

THe formula for SI units is wrong. If I give F in Newton [N], the number will be by factor 9.80665 larger than the corresponding value in kilogram-force [kgf]. To get the same result for F/A the factor 1.8544 needs to be divided by 9.80665, not multiplied.

see also: www.materials.co.uk/vickers.htm

— Preceding unsigned comment added by 101.160.172.66 (talk) 09:28, 21 December 2011 (UTC)

What is the real conversion to MPa?[edit]

I've seen both the kgf to N conversion, as well as another number all together: Multiple sources show 100HV as 320MPa. However 100 kgf/mm^2 = 981 N/mm^2 = 981 MPa. So which is it? Is one an estimator of yield strength and the other a pressure on the surface? For thermal contact resistance I'm assuming that the SI conversion would be the proper one. — Preceding unsigned comment added by Smjanows (talkcontribs) 21:36, 26 March 2014 (UTC)