Thermal Deformation Behavior and Constitutive Relationship of Laves Phase NbCr2/Nb Dual-phase Alloy

The isothermal constant strain rate compression test of the Laves phase NbCr2/Nb dual-phase alloy prepared by mechanical alloying and hot pressing was carried out on a Gleeble-3500 thermal simulation tester. The flow stress behavior of the alloy was investigated in the temperature range of 800~1200 ℃ and the strain rate range of 0.001~0.1 s-1 and the constitutive relations based on the hyperbolic sinusoidal function Arrhenius equation and the stepwise regression method were established. The results show that the ductile to brittle transition temperature (DBTT) of Laves NbCr2/Nb dual-phase alloy is 950~1000 ℃. The alloy breaks into pieces directly without yield below 950 ℃. While, it shows a good plastic deformation ability above 1000 ℃. The flow stress of the alloy decreases with the increase of deformation temperature and the decrease of strain rate. It is characterized by steady-state flow under the deformation conditions of 1050~1200 ℃/0.001 s-1 and 1150~1200 ℃/0.01 s-1. While, it shows the flow softening under the deformation conditions of 1000 ℃/0.001 s-1, 1000~1100 ℃/0.01 s-1 and 1000~1200 ℃/0.1 s-1. The AARE of the peak flow stress constitutive relation and the strain-compensated constitutive relation, which are established based on hyperbolic sinusoidal function Arrhenius equation, is 9.89% and 13.859%, respectively. The AARE of the constitutive relation under all experimental conditions, the steady-state flow stress curve constitutive relation and the softening flow stress curve constitutive relation, which are established based on stepwise regression method, is 8.63%, 5.28% and 6.83%, respectively. The established constitutive relation can provide theoretical guidance and basic data for forging process design, forging equipment tonnage selection and forging process finite element numerical simulation of the Laves phase NbCr2/Nb dual-phase alloy. © 2021, Science Press. All right reserved.