An accurate flow stress model was established by considering the parameters of strain rate,strain and temperature as well asβ→a+βphase transformation in order to develop the plastic forming theory of TC18 titanium ...An accurate flow stress model was established by considering the parameters of strain rate,strain and temperature as well asβ→a+βphase transformation in order to develop the plastic forming theory of TC18 titanium alloy.Firstly,the phase transition kinetics of TC18 titanium alloy during isothermal and continuous cooling at 1073 and 1273 K was studied by thermodynamic calculation,meanwhile,the relationship of volume fraction of phase transition with temperature and time was obtained.Constitutive models were calculated by investigating flow behaviors under hot compression tests with the strain rates of 0.001-1s^(-1) and temperatures of 973-1223 K in the singleβand a+βregions in TC18 titanium alloy,respectively.By combining the phase transformation dynamic kinetics with constitutive models,an accurate flow stress model was established,providing theoretical basis and data support for the hot forging of TC18 titanium alloy.展开更多
The hot deformation behavior of TC18 alloy at strain rates ranging from 1 × 10-4 to 1 x 10-2 s-1 and temperatures ranging from 25 to 800 ℃ was studied using a WDW-300 electronic universal testing machine. The re...The hot deformation behavior of TC18 alloy at strain rates ranging from 1 × 10-4 to 1 x 10-2 s-1 and temperatures ranging from 25 to 800 ℃ was studied using a WDW-300 electronic universal testing machine. The relationships between true flow stress decreases with stress and true strain show that the increase of temperature and increases as strain rate increases. The effect of strain rate on the flow stress becomes pronounced at higher temper- atures. At room temperature, the river pattern characteristic of brittle fracture and the dimple pattern typical of ductile fracture are found to exist in different regions of fracture surfaces of the samples. An improved constitutive rela- tionship is proposed to accurately describe the flow stress of TC18 by considering the effect of strain. And a micro- scopic model is also deduced which can link the physical mechanisms to the macroscopic experimental results. A good agreement is obtained between the predictions of the microscopic model and the results of the macroscopic experiment.展开更多
基金Funded by the National Natural Science Foundation of China(No.52075058)the Natural Science Foundation of Chongqing(No.cstc2021jcyj-msxmX1112)the Research and Demonstration of Key Technologies for Forging High-performance Aluminum Alloys for Aerospace Applications(No.Z20210348)。
文摘An accurate flow stress model was established by considering the parameters of strain rate,strain and temperature as well asβ→a+βphase transformation in order to develop the plastic forming theory of TC18 titanium alloy.Firstly,the phase transition kinetics of TC18 titanium alloy during isothermal and continuous cooling at 1073 and 1273 K was studied by thermodynamic calculation,meanwhile,the relationship of volume fraction of phase transition with temperature and time was obtained.Constitutive models were calculated by investigating flow behaviors under hot compression tests with the strain rates of 0.001-1s^(-1) and temperatures of 973-1223 K in the singleβand a+βregions in TC18 titanium alloy,respectively.By combining the phase transformation dynamic kinetics with constitutive models,an accurate flow stress model was established,providing theoretical basis and data support for the hot forging of TC18 titanium alloy.
基金financially supported by the National Natural Science Foundation of China(Nos.91016013 and 11221202)the Opening Research Fund of State Key Laboratory of Porous Metal Materials(No.PMM-SKL-1-2012)the Project of State Key Laboratory of Explosion Science and Technology(No.SKLEST-13-07)
文摘The hot deformation behavior of TC18 alloy at strain rates ranging from 1 × 10-4 to 1 x 10-2 s-1 and temperatures ranging from 25 to 800 ℃ was studied using a WDW-300 electronic universal testing machine. The relationships between true flow stress decreases with stress and true strain show that the increase of temperature and increases as strain rate increases. The effect of strain rate on the flow stress becomes pronounced at higher temper- atures. At room temperature, the river pattern characteristic of brittle fracture and the dimple pattern typical of ductile fracture are found to exist in different regions of fracture surfaces of the samples. An improved constitutive rela- tionship is proposed to accurately describe the flow stress of TC18 by considering the effect of strain. And a micro- scopic model is also deduced which can link the physical mechanisms to the macroscopic experimental results. A good agreement is obtained between the predictions of the microscopic model and the results of the macroscopic experiment.
