Creep Behaviour of Fe--Mn Binary Alloys

Tensile creep behaviour of fine-grained Fe--Mn binary alloys containing 0.42--1.21wt.% Mn has been investigated in the temperature range from room temperature to 475K under 10--50MPa. Tensile tests are carried out with a constant cross-head speed under uniaxial load at a strain rate 10^-4s^-1. Stress exponent and activation energy are determined to clarify deformation mechanism. The obtained variation of steady state creep rate with respect to the applied stress for Fe--Mn binary alloys exhibits two distinct regimes at about 20MPa, indicating a possible change in creep mechanism. The average stress exponent is approximately 2.2, which is a characteristic of grain boundary sliding in the alloys. The activation energy for plastic flow varies from 135 to 92kJ/mol, depending on the Mn content.