Hot deformation behavior of Fe-28Ni-17Co-11.5Al-2.5Ta-0.05B (at.%) shape memory alloy by isothermal compression

A Gleeble-3800 thermomechanical simulator was used to conduct experiments at deformation temperatures varying between 1050 and 1200 degrees C and strain rates varying between 0.01 and 10 s(-1) with the maximum strain of 0.6. Processing maps incorporating efficiency map and instability map were generated using the dynamic material model (DMM). Deformation mechanisms were investigated using true stress-true strain curves, processing maps, kinetic analysis, and microstructural analysis. A constitutive equation was established in the form of an Arrhenius hyperbolic sine function, which yielded an activation energy of similar to 412 kJ/mol for deforming the alloy at elevated temperature. Based on the process map, optimum process parameters for the formation of recrystallized grains during the hot deformation of the sample were predicted to be T = 1100 degrees C and (epsilon) over dot = 0.01s(-1), which were also verified by microstructural analysis. Based on an analysis of the work-hardening characteristics, the critical conditions for the deformation were found to be, sigma(s) = 0.88 sigma(p), sigma(c) = 0.95 sigma(p), and epsilon(s) = 0.24 epsilon(p). Cingara-Queen model was used to determine the flow curve until the peak value of flow stress. This model is highly compatible with the experimental findings as validated by the high correlation coefficient (Adj. R-2 = 0.9851).