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<p>[QUOTE=&quot;RonSanderson, post: 3373748, member: 77413&quot;]Very intriguing. I did not know that, but it sure makes sense.</p><p><br /></p><p>I tracked down some images of rolled steel for comparison. This is apparently hot rolled steel, in contrast to cold rolled steel which is cooled to room temperature before the rolling process. But it&#039;s the kind or grain structure I would expect to see.</p><p>[ATTACH=full]894918[/ATTACH]</p><p><i><span style="color: #0059b3">Figure 3: (a) Microstructure of 52100 steel as supplied by the manufacturer, in a hot rolled condition. (b) The microstructure after spheroidisation. Micrographs courtesy of W. Trojahn.</span></i></p><p><br /></p><p>The point being, that rolling with steel balls should create a similar grain structure in the Nickel alloy that we see in the steel above. Granted, the scale is different, but the fields in the photograph in post <a href="https://www.cointalk.com/threads/posting-jefferson-nickels-in-order-by-date.322759/page-23#post-3373437" class="internalLink ProxyLink" data-proxy-href="https://www.cointalk.com/threads/posting-jefferson-nickels-in-order-by-date.322759/page-23#post-3373437">#455</a> show the same kind of small domains that absorb or reflect light differently. </p><p><br /></p><p>It is very easy to imagine the planchet started out rough and those dings and gouges were then hammered flat. It would pinch together the sides of any marks. Left behind would be traces of small domains where the metal flows one way or another depending on how the ball bearings beat down on it.</p><p><br /></p><p>Since this is similar to the hardening process used to make cold rolled steel, which is used for bearing shafts and other hardened applications, I absolutely agree that these hardened small regions would retain their identity even through the striking process. </p><p><br /></p><p>I like the theory.[/QUOTE]</p><p><br /></p>

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