Sciencemadness Discussion Board

What force is needed to deform gold ?

noxx - 7-10-2008 at 13:21

Hello,
I am doing some personal research on what force is needed to deform a certain metal. In fact, I want to know how much force is needed to press a small gold bar.
I looked on the internet about a certain formula that I could use to calculate it but I had no success. The closest formula I found is the Young's modulus formula but it does not seem to be appropriate for this application, since I end up with 1 000 000 pounds needed lol.

Please fellow chemists or physicists, help me !

Thanks in advance.

chief - 7-10-2008 at 14:27

There is such a thing as the "hardness" or "microhardness" of a material, the unit is that of pressure, usually GPa.
If something has a hardness of eg. 5 GPa, then it will not deform below about that pessure, which would mean: 5 GPa == 5 GigaNewton/m^2 == 50000 kg/cm^2 == 50 kBar.

That sort of hardness is usually measured by means of a special microscope, that allows applying a force (diamond-tip) onto the sample, and then measure the crater ...
But it's a raw approximation, since materials have all sorts of elacticity, get harder under pressure (nonlinearity), ...

noxx - 7-10-2008 at 14:36

Ok I see. But is the harness the minimum force needed to deform (flatten) a metal ?

Thank for the answer.

watson.fawkes - 7-10-2008 at 21:22

Quote:
Originally posted by noxx
I am doing some personal research on what force is needed to deform a certain metal. In fact, I want to know how much force is needed to press a small gold bar.
I looked on the internet about a certain formula that I could use to calculate it but I had no success. The closest formula I found is the Young's modulus formula but it does not seem to be appropriate for this application, since I end up with 1 000 000 pounds needed lol.
To press it all at once? Yeah, it's a lot of force. How is gold actually worked? Pressed on not all at once. See "peening".