I've had this test idea for a few days now....been too busy to try it though. I want to take two identical pieces of metal, like two nails or two pieces of coat hanger or something like that. Bend each of them 90 degrees, then back straight again, then back 90 degrees. The idea being to induce some stress micro-fractures at the bending point. Important to bend both pieces excactly the same, the exact number of times.
Then place one piece of metal in a cup of Coca Cola. Set the other piece aside. After one day, continue the bending-back-and-forth process. Count the number of bendings until the metal breaks. Which piece breaks first? Is there a significant difference in the bend count between the two pieces?