Utilisation de plomb pur pour illustrer, à température ambiante, la déformation en fluage de superalliages à haute température

Discovering the tensile creep phenomenon, using superalloys, by practical work is neither easy, nor with sufficient safety, nor cheap and nor fast enough to be done in a single session. The present study, which is based on the creep of lead at ambient temperature, can be taken as the assembly and the test of a workstation to allow students in Master of Metallurgy or in Materials Science, to experimentally explore the creep phenomenon. This can be done, eventually by conceiving the manipulation themselves and using it, or by exploiting a manipulation previously mounted. In both cases, they can discover, with they own experiences, the three classical steps of a creep deformation, eventually until the final rupture, and investigate the dependence of the steady state creep rate on the constant applied stress and on temperature. Using lead and a device made of very simple and cheap components, allows establishing {time  strain} curves on which one can clearly distinguish the primary, secondary (steady state) and tertiary creep steps, as well as the final rupture. Broken specimens can be of course available for post-mortem measurement of the permanent elongation, the striction… Furthermore, carrying out tests for several stresses (by varying either the gauge section or the hanged mass) and for several temperatures around the ambient temperature, may offer to students the opportunity to re-build themselves the power or exponential laws and to deduce the values of the multiplying constants, exponent and activation energy.