Effect of Temperature and Strain Rate on Deformation Behavior of Zirconium Alloy: Zr-2.5Nb-0.5Cu

Abstract

Hot workability of Zr alloy has been investigated by means of hot compression test using Gleeble-3800. Hot compression test was performed in the temperature and strain rate range of 700 to 925 o C and 0.01 -10s -1 , respectively. Deformation behavior was characterized with the help of processing maps using Dynamic Material Model (DMM). From the power dissipation map peak efficiency of 48-55% was obtained at temperature of around 750 o C and strain rate of 1×10 -2 s -1 , in (α +β) phase field. High efficiency suggests dynamic recrystallization and therefore is preferred processing condition. A domain of unstable flow was obtained at temperature range 700-730°C and strain rate range of 8×10 -2 -1s -1 in which instability parameter is negative. This region should be avoided during hot working. Effect of Cu in addition to Zr-2.5Nb also studied by power dissipation and instability map in this present study.

Determination of Instability in Zr-2.5Nb-0.5Cu Using Lyapunov Function

“…Higher the softening degree, results in decreasing flow stress up to the saturated flow stress. This softening behaviour is term as dynamic recrystallization (DRX) which arises during the hot deformation at the strain exceeds to critical strain [3,4].…”

Hot deformation behaviour of Ti alloys: A review on physical simulation and deformation mechanisms

“…Different material models are reported in the literature to develop the processing maps based on the method to calculate the efficiencies of deformed materials. Some of the developed maps are Raj map, 94 deformation mechanism map, 95 α parameter, 96 dynamic materials model (DMM), 97 modified dynamic materials model (MDMM). 98 These are often called as processing maps.…”

“…The two models that are based on the strain rate sensitivity of flow stress are DMM and MDMM. DMM considers the constant strain rate sensitivity, 8,94,100–102 whereas MDMM considers the variable strain rate sensitivity. 33 On the other hand, the α-parameter considers both strain rate sensitivity and strain hardening to define the safe processing conditions.…”

“…From the available approaches, various researchers have predicted the safe/stable and unsafe/unstable processing conditions for different Ti alloys. 47,94,102 Most of the researchers used DMM mode, 68,103–109 some of them used MDMM 46 and the α-parameter approach is rarely used 110 to predict the processing parameters.…”