Hot deformation characteristics of NiTiV shape memory alloy and modeling using constitutive equations and artificial neural networks

• Hot compression tests were carried out on Ni 50 Ti 48 V 2 (at.%) SMA samples using Gleeble 3800 thermomechanical simulator. • It shows a maximum power dissipation efficiency of 43.5% and the activation energy of the alloy was 205.78 kJ/mol. • SCAT and ANN models were employed to predict the flow stress values and were compared to that of experimental results. • Based on the work hardening theory, onset of DRX and critical stresses were identified. In this study, an alloy conforming to the composition Ni 50 Ti 48 V 2 (at. %)was cast in a vacuum induction melting furnace, and hot deformation tests were performed on the samples using a GLEEBLE 3800 thermomechanical simulator over a range of strain rates (0.01 s −1 , 0.1 s −1 , 1 s −1 , 10 s −1 ) and temperatures (1073 K, 1173 K, 1273 K, 1373 K). Deformation processing maps, which are a combination of instability map and efficiency map, were derived based on dynamic materials model. The mechanisms of deformation were interpreted based on stress-strain plots, kinetic analysis, process maps and microstructure. Material constants along with activation energy, which was found out to be 205.58 kJ/mol., were calculated. Since strain also plays a major role in this analysis, a Strain-Compensated Arrhenius-Type (SCAT) model was developed. A comparison between strain-compensated Arrhenius type and artificial neural network models (ANNM) was made through the use of relative error, adjusted R 2 values and root mean square errors between the predicted and experimental stress values. All three parameters unanimously indicated the use of ANNM for predicting the stresses developed in the material during hot deformation process. Finally, the flow stress required for the onset of dynamic recrystallization (DRX) was calculated using work hardening theory and correlated with the power dissipation efficiency generated from processing maps. Results show that Ni 50 Ti 48 V 2 exhibits the highest power dissipation efficiency of 43.50% when deformed at 1173 K and 0.01 s −1 . The least critical stress of 58.014 MPa was also captured under the same working conditions. Results are elaborately discussed in the paper.