Ancient coins get their luster from being a liquid poured silver that was then struck. Totally different from being punched from a rolled drawn sheet.
Yeah, I'm not going to join a physics forum just to discuss material properties with you. The discussion relates to coins via your original post, so I don't see the problem. You stated that you could explain the malleability of elements using the periodic table, and I would like to hear what you have to say. As for the original discussion, we have tried to tell you that coins don't liquify and re-solidify during the coining process, but you just don't want to hear it. The coining process causes plastic deformation (flow) because the stresses applied exceed the yield strength of the material. The pressure exerted does not raise the surface temperature of the metal to the melting point. Here are the melting points per Doug's request. Copper: 1983 F Coin Silver: 1615 F Pure Gold: 1945 F CuNi: 2140 F I think that part of you unwillingness to accept what we are saying is related to credibility. As an FYI, I have a degree in metallurgy.
Sorry but that is incorrect. Were some ancient coins cast as you describe ? Yes, but very few. Most were made by mint workers hammering out a sheet of gold, silver, or copper, by hand until it was the desired thickness. Planchets were then cut, by hand, out of that sheet. The planchets were then placed on an anvil die, a hammer die was then placed on top of it, and the hammer die struck with a hammer, by hand. That is how the coins were made. And yes, they have luster. This same method was used until 1643 when the French invented milled coinage. All of this is well known and very well documented. Contemporary texts describing the process still exist today as do the tools and implements used. I'm sorry, but what you are describing, is simply not true.
I just hit a copper wire held against an anvil with a hammer and it squished out!!! Does that mean I melted it???
Better yet, try it with a platinum wire. More malleable than zinc, and melts at 3215 F vs. 787 F. @Hommer, your heart is in the right place, but you're just flat wrong about melting.
Most metals will remain in its solid state if you increase pressure and hold the temperature constant. It may yield and undergo plastic deformation but it won't melt. Water will phase shift from solid (ice) to liquid (water) with a pressure increase alone, but water is just weird that way. Increasing temperature alone will make metals go from solid to liquid if you increase it enough ( ). If you increase pressure too, then you will generally need to increase temperature even more so to get it to melt. Increasing pressure rapidly (like when a coin is minted or when a train runs over a coin or when Kentucky boy goes medieval on an innocent piece of wire with a hammer ) will result in some increase in temperature (conversion of some of the kinetic energy into heat), but not enough to melt metal. Another thing, the pressure increase comes and goes long before the temperature increase can penetrate to any significant depth.
@Hommer, here is the periodic table listed by crystal structure. FCC crystal structures are more malleable than HCP which are more malleable than BCC. Now, if you can explain why, that will impress me.
The "science" displayed by the OP here is highly questionable at best.... I suggest you read a couple of books about coins, and their manufacture. Roger Burdette's "From Mine to Mint" comes most readily to mind, and explains everything that you are attempting to say (and, of course, contradicts you at many points). Readers interested in learning about luster are recommended to view my thread (kindly linked by Doug), or can pick up my book on Amazon (linked below in my signature).
I find this whole thread entertaining, but fundamentally flawed. I design high pressure pumps for the oil and gas industry and have developed a pneumatic pump capable of 170,000 PSIA for hydrostatic testing of pipelines. These pumps are made of 316SS, 304SS, 2205, 2507, 17-4, N-25 and C-276. None of these pumps have ever shown any sign of melting under pressure. Before you say that it is not the same thing, understand that water at extreme pressures can pose friction as high as any other means and these pumps are cyclical meaning that the wetted materials go from max pressure to a vacuum hundreds of times per minute. NOAH uses my pumps to simulate deep ocean pressures to test submarines.
