Determination of the strain rate sensitivity of a superplastic material at constant load test

It is shown that the value of strain rate sensitivity index, m, can be determined experimentally using a constant load test. The method suggested is compared with standard procedures. The conclusion is circumbents the influence of the finite stiffness and inertia of the testing machine. The compression response of a superplastic Pb-Sn eutectic alloy (Sn—38.1%Pb) is used to confirm the applicability of the method proposed.