<blockquote style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;" class="gmail_quote">The following link may also be helpful, as it goes directly to the question of whether a string can experience plastic deformation despite being well under yield strength limits.</blockquote><div> Thanks. From that page: "...creep deformation does not occur suddenly upon the application of stress. Instead, strain accumulates as a result of long-term stress. Creep deformation is "time-dependent" deformation." This sounds exactly like what we are talking about... until you get to this: "Generally, the minimum temperature required for creep deformation to occur is 30% of the melting point for metals." By my calculations, that would be about 750 degrees F. That is one hot piano. Kurt </div>