The hot deformation behaviors of Ni18 Cr9 Co9 Fe5 Nb3 Mo superalloy were explored in the formation temperature range free ofγ’phase with various strain rates applied.The hot deformation behaviors are initially model...The hot deformation behaviors of Ni18 Cr9 Co9 Fe5 Nb3 Mo superalloy were explored in the formation temperature range free ofγ’phase with various strain rates applied.The hot deformation behaviors are initially modeled with Arrhenius equation which gives an average activation energy of 581.1 kJ mol^(-1).A modified Arrhenius approach,including the updated Zener-Hollomon parameter is proposed to consider the change of activation ene rgy under different deformation conditions which turns out a relatively accurate computation for activation energy of hot deformation,i.e.,the standard variance for modified model calculated in the covered deformation condition is just 35.4%of that for Arrhenius equation.The modified model also proposes a map for activation ene rgy which ranges from 571.5-589.0 kJ mol^(-1)for various deformation conditions.Microstructural features of the representative superalloy specimens were characterized by electron backscattered diffraction(EBSD)techniques in order to clarify the influence of activation energy on the microstructural formation.It is found that the Ni-based superalloy samples with higher activation energy are promoted by the degree of dynamic recrystallization which suggests that the rise in activation energy gives either a better recrystallization rate or finer grains.展开更多
In order to predict flow instability of wear-resistant steel BTW1, the hot compressions of wear-resistant steel BTW1 were firstly performed at the temperature of 900-1150 ℃ and at the strain rate of 0.05-15 s-1. Then...In order to predict flow instability of wear-resistant steel BTW1, the hot compressions of wear-resistant steel BTW1 were firstly performed at the temperature of 900-1150 ℃ and at the strain rate of 0.05-15 s-1. Then, the constitutive relation was established based on Arrhenius-type hyperbolic sine equation. The results demonstrated that the flow stress depended on the deformation temperature and strain rate. When the deformation temperature kept constant, the flow stress increased as the strain rate increased. When the strain rate remained constant, the flow stress decreased as the temperature increased. The flow stresses calculated by constitutive equations were in a good agreement with experimental results. The apparent activation energy for deformation in the above processing region was estimated to be 369 kJ tool-1. A processing map could be obtained by the superimposition of an instability map on a power dissipation map. Based on the analysis of processing map and the microstructures, the theological instability regimes of strain rate and temperature for hot deformation of wear-resistant steel BTWl had been identified.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.52034004 and 51975404)。
文摘The hot deformation behaviors of Ni18 Cr9 Co9 Fe5 Nb3 Mo superalloy were explored in the formation temperature range free ofγ’phase with various strain rates applied.The hot deformation behaviors are initially modeled with Arrhenius equation which gives an average activation energy of 581.1 kJ mol^(-1).A modified Arrhenius approach,including the updated Zener-Hollomon parameter is proposed to consider the change of activation ene rgy under different deformation conditions which turns out a relatively accurate computation for activation energy of hot deformation,i.e.,the standard variance for modified model calculated in the covered deformation condition is just 35.4%of that for Arrhenius equation.The modified model also proposes a map for activation ene rgy which ranges from 571.5-589.0 kJ mol^(-1)for various deformation conditions.Microstructural features of the representative superalloy specimens were characterized by electron backscattered diffraction(EBSD)techniques in order to clarify the influence of activation energy on the microstructural formation.It is found that the Ni-based superalloy samples with higher activation energy are promoted by the degree of dynamic recrystallization which suggests that the rise in activation energy gives either a better recrystallization rate or finer grains.
基金This work was supported by the National Natural Science Foundation of China （No. U1510131） and the Applied Basic Research Project of Shanxi Province （Nos. 201701D121078 and 201701D221143）.
文摘In order to predict flow instability of wear-resistant steel BTW1, the hot compressions of wear-resistant steel BTW1 were firstly performed at the temperature of 900-1150 ℃ and at the strain rate of 0.05-15 s-1. Then, the constitutive relation was established based on Arrhenius-type hyperbolic sine equation. The results demonstrated that the flow stress depended on the deformation temperature and strain rate. When the deformation temperature kept constant, the flow stress increased as the strain rate increased. When the strain rate remained constant, the flow stress decreased as the temperature increased. The flow stresses calculated by constitutive equations were in a good agreement with experimental results. The apparent activation energy for deformation in the above processing region was estimated to be 369 kJ tool-1. A processing map could be obtained by the superimposition of an instability map on a power dissipation map. Based on the analysis of processing map and the microstructures, the theological instability regimes of strain rate and temperature for hot deformation of wear-resistant steel BTWl had been identified.
