Effect of Temperature, Strain and Strain Rate on Efficiency of Power Dissipation during Hot Deformation of Fe-28Ni-17Co-11.5Al-2.5Ta-0.05B (at. %) Shape Memory Alloy Using Taguchi Method

Abstract

Recently a ferrous-based Fe-28Ni-17Co-11.5Al-2.5Ta-0.05B (at.%) shape memory alloy (abbreviated NCATB) has attracted attention because of its huge superelasticity (～13%). In order to manufacture this alloy on a large scale, a deeper knowledge of the plastic deformation behaviour of the alloy is required. During hot deformation, temperature and strain rate exert significant effect on the mechanical properties. The main objective of the work, therefore, is to investigate the influence of deformation parameters, such as temperature, strain rate and strain, on flow behaviour of an NCATB shape memory alloy. Flow behaviour tests on an NCATB alloy were performed on a Gleeble-3800 thermomechanical simulator at deformation temperatures of 1100, 1150 and 1200°C and strain rates of 0.1, 1.0 and 10s-1 with the strains maintained at 0.2, 0.4 and 0.6, respectively. The workpiece is considered asa dissipater of power, and the features of power dissipation will,therfore, be seen as changes in the microstructure. These features of power dissipation are measured by a parameter called efficiency of power dissipation (η). It is directly related to the strain rate sensitivity parameter(m). Taguchi method is used to evaluate the influence of deformation temperature, strain rate and strain on efficiency of power dissipation. Based on the results, optimum parameters for higher efficiency of power dissipation are: 1150°C (temperature), 0.1 s-1 (strain rate) and 0.2 (strain). An analysis of experimental results in terms of percentage contribution reveals that strain rate plays a more predominant role (39.73%) compared to temperature (24.03%) and strain (32.73%) on NCATB alloy.