The kinetics of dynamic globularization during hot working of a two phase titanium alloy with starting lamellar microstructure

Ma, Xiong; Zeng, Weidong; Tian, Fuqiang; Zhou, Yigang

doi:10.1016/j.msea.2012.03.022

Cited by 62 publications

(13 citation statements)

References 9 publications

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“…6, k and n mainly increase with increasing temperature and decreasing strain rate, while e c decreases with increasing temperature and decreasing strain rate. The similar phenomena were observed in other titanium alloys (Ref 23,30). Therefore, to establish the prediction model more accurately, the influence of the temperature and strain rate can be taken into account by assuming that the parameters in Eq 1 (i.e., k, e c , and n) are polynomial functions of the temperature and strain rate ( Ref 31).…”

Section: The Model For Dynamic Globularizationmentioning

confidence: 53%

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Development of the Dynamic Globularization Prediction Model for Ti-17 Titanium Alloy Using Finite Element Method

Jia

Zeng

et al. 2015

J. of Materi Eng and Perform

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In this work, a finite element method (FEM) model for predicting dynamic globularization of Ti-17 titanium alloy is established. For obtaining the microstructure evolution during dynamic globularization under varying processing parameters, isothermal hot compression tests and quantitative metallographic analysis were conducted on Ti-17 titanium alloy with initial lamellar microstructure. The prediction model, which quantitatively described the non-linear relationship between the dynamic globularization fraction and the deformation strain, temperature, and strain rate, was developed on the basis of the Avrami equation. Then the developed model was incorporated into DEFORM software as a user subroutine. Finally, the large-sized step-shaped workpiece was isothermally forged and corresponding FEM simulation was conducted to verify the reliability and accuracy of the integrated FEM model. The reasonable coincidence of the predicted results with experimental ones indicated that the established FEM model provides an easy and a practical method to predict dynamic globularization for Ti-17 titanium alloy with complex shape.

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Section: The Model For Dynamic Globularizationmentioning

confidence: 53%

“…Recent studies indicated that the deformation temperature and strain rate play significant roles on the parameters in Eq 1 (i.e., k, e c , and n) among the whole process of dynamic globularization ( Ref 23,30). Figure 6 depicts the relationships between them.…”

Section: The Model For Dynamic Globularizationmentioning

confidence: 99%

Development of the Dynamic Globularization Prediction Model for Ti-17 Titanium Alloy Using Finite Element Method

Jia

Zeng

et al. 2015

J. of Materi Eng and Perform

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“…Three micrographs of each specimen were used to analyze microstructure evolution, thus ensuring that about 800 to 1000 particles were analyzed (Ref 10,13,16). The micrographs were examined using a quantitative metallographic image analysis system (Image-pro plus 5.0), and this software had been widely used to investigate globularization behavior of titanium alloys ( Ref 6,13,19,20). Figure 2 indicates microstructure evolution after deformation at 1103 J to a strain of 0.52 and heat treatment at the same temperature for different times.…”

Section: Methodsmentioning

confidence: 99%

Coarsening Kinetics and Morphological Evolution in a Two-Phase Titanium Alloy During Heat Treatment

Zeng

Jia

et al. 2016

J. of Materi Eng and Perform

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The effects of alpha/beta heat treatment on microstructure evolution of Ti-17 alloy with a lamellar colony structure are established. Heat treatment experiments are conducted at 1103 or 1063 K for times ranging from 10 min to 8 h. The main features of microstructure evolution during heat treatment comprise static globularization and coarsening of primary alpha phase. Such behaviors can be accelerated by higher heat treatment temperature. Furthermore, globularization and coarsening behaviors show a faster rate at higher prestrain. In order to better understand the microstructure evolution of Ti-17 alloy during alpha/beta heat treatment, static globularization and coarsening behaviors are modeled in the theoretical frame of the Johnson-Mehl-Avarmi-Kolmogorov (JMAK) and Lifshitz-Slyozov-Wagner (LSW) theories, respectively. The JMAK and LSW kinetics parameters are derived under different experimental conditions. Agreements between measurements and predictions are found, indicating that the JMAK and LSW theories can be used to predict and trace static globularization and coarsening processes of Ti-17 alloy during alpha/beta heat treatment.

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“…Modelling of dynamic globularization of lamellae during the hot working of titanium alloys, to obtain an equiaxed microstructure, plays an important role in process optimisation. It has been reported that the globularization is initiated at a critical strain and the globularization fraction increases with strain in a sigmoid way [9,11]. The Avramitype equation is often employed to depict the variation of globularization fraction with strain [9,11,12].…”

Section: Introductionmentioning

confidence: 99%

“…It has been reported that the globularization is initiated at a critical strain and the globularization fraction increases with strain in a sigmoid way [9,11]. The Avramitype equation is often employed to depict the variation of globularization fraction with strain [9,11,12]. A backpropagation artificial neural network (ANN) based model was developed by Wang et al [13] for predicting the dynamic globularization fraction of Ti-17 alloy during hot forming.…”

Section: Introductionmentioning

confidence: 99%

Unified constitutive modelling for two-phase lamellar titanium alloys at hot forming conditions

Yang

Wang

et al. 2016

Manufacturing Rev.

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-In this paper, a set of mechanism based unified viscoplastic constitutive equations have been established for two-phase titanium alloys with initial lamellar microstructure, which models the softening mechanisms of the alloys in hot forming conditions. The dislocation density, rotation and globularization of lamellar a-phase and their effects on flow behaviour can also be modelled. The values of material constants in the equation set have been calibrated, according to stress-strain curves and globularization fractions of lamellar a-phase obtained from compression tests at a range of temperatures and strain rates, using a genetic algorithm (GA) based optimisation method. Based on the determined constitutive equations, flow stress and globularization evolution of Ti-17 and TA15 alloys at different temperatures and strain rates were predicted. Good agreements between the experimental and computed results were obtained.

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The kinetics of dynamic globularization during hot working of a two phase titanium alloy with starting lamellar microstructure

Cited by 62 publications

References 9 publications

Development of the Dynamic Globularization Prediction Model for Ti-17 Titanium Alloy Using Finite Element Method

Development of the Dynamic Globularization Prediction Model for Ti-17 Titanium Alloy Using Finite Element Method

Coarsening Kinetics and Morphological Evolution in a Two-Phase Titanium Alloy During Heat Treatment

Unified constitutive modelling for two-phase lamellar titanium alloys at hot forming conditions

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