Constitutive Model Parameter Identification Based on Optimization Method and Formability Analysis for Ti6Al4V Alloy

Abstract

Titanium alloy is widely applied in aerospace, medical, shipping and other fields due to its high specific strength and low density. The purpose of this study was to analyze the formability of Ti6Al4V alloys at elevated temperatures. An accurate constitutive model is the basic condition for accurately simulating the plastic forming of materials, and it is an important basis for optimizing the parameters of the hot forging forming process. In this study, the optimization algorithm was used to accurately identify the high-temperature constitutive model parameters of Ti6Al4V titanium alloy, and the hot working diagram was established to optimize the hot forming process parameters. The optimal forming conditions of Ti6Al4V titanium alloy are given. Ti6Al4V alloy was subjected to high-temperature compression tests at 800–1000 °C and at strain rates of 0.01–5 s−1 on a Gleeble-1500D thermal/mechanical simulation machine. Each parameter of the Hansel–Spittel constitutive model was taken as an independent variable, and the accumulated error between the stress calculated by the constitutive model and the stress obtained by experimentation was used as an objective function. Based on response surface methodology, an inverse optimization method for identifying the parameters of the high-temperature constitutive model of Ti6Al4V alloy is proposed in this paper. An orthogonal test design was adopted to obtain sample point data, and a third-order response surface approximate model was established. The genetic algorithm (GA) was applied to reversely optimize the parameters of the constitutive model. To verify the accuracy of the optimized constitutive model, the average absolute relative error (AARE) and correlation coefficient (R) were used to evaluate the reliability of optimized constitutive model. The R value of the model was 0.999, and the AARE value was 0.048, respectively, indicating that the established high-temperature constitutive model for Ti6Al4V alloy has good calculation accuracy. The flow stress behavior of the material could be accurately delineated. Meanwhile, in order to study the formability of Ti6Al4V alloy, the hot processing map of the alloy, based on a dynamic material model, was established in this paper. The optimum hot working domains of the Ti6Al4V alloy were determined within 840–920 °C/0.01–0.049 s−1 and 940–980 °C/0.11–1.65 s−1; the hot processing map was verified in combination with the microstructure, and the fine and equiaxed grains and a large amount of β phase could be found at 850 °C/0.01 s−1.

Simulation and Optimization of Connection-Strength Performance of Axial Extrusion Joint

“… is an integer from 1 to 10. The range of hidden neurons obtained by substituting data is [ 3 , 13 ]. The number of hidden neurons obtained by trial algorithm is 8.…”

“…High-strength titanium-alloy (TA) tubes not only have good room temperature and high-temperature mechanical properties and corrosion resistance, but also have excellent cold- and hot-processing plasticity and formability [ 3 , 4 ]. It is suitable for high-pressure, lightweight hydraulic and fuel pipeline systems [ 5 ].…”

Cold Rolling Technology Optimization for EN AW 4343/3003/4343 Cladded Aluminum Alloys and Influence of Parameters on Microstructure, Mechanical Properties and Sustainable Recyclability

“…These curves were essential for calculating the factors (m1, m2, m3, and m4) in the Hansel-Spittel equation, serving as descriptors of the material's mechanical properties for numerical simulations. According to the obtained stress-strain curves from dilatometry, the factors in the Hansel-Spittel Equation (1), which are sufficient for material inventory during cold forming, where T is temperature, ε is strain, and 𝜀 is strain rate [18], for the material property description in numerical simulations, were calculated for cladded EN AW 3003 aluminum alloy and compared with the uncladded EN AW 3003 aluminum alloy for the cold rolling technology scheduling.…”

An Inverse Optimization Method for the Parameter Determination of the High-Temperature Damage Model and High-Temperature Damage Graph of Ti6Al4V Alloy

“…Therefore, in this paper, the Hansel–Spittel constitutive model was used to accurately characterize the Ti6Al4V alloy’s flow stress behavior at high temperatures, as shown in Equation (1). The parameters were obtained from previous studies [ 30 ] and are listed in Table 2 . where is the temperature-related coefficient, is the strain-hardening exponent, is the strain-rate-hardening exponent, is the strain-softening coefficient, is the temperature–strain coupling coefficient, is the strain-strengthening coefficient, is the strain rate–temperature coupling coefficient, is temperature-strengthening exponent, A is a material constant, is the flow stress (MPa), T is the temperature (K), is the strain rate (s −1 ), and is the plastic strain.…”

“…Therefore, in this paper, the Hansel-Spittel constitutive model was used to accurately characterize the Ti6Al4V alloy's flow stress behavior at high temperatures, as shown in Equation ( 1). The parameters were obtained from previous studies [30] and are listed in Table 2.…”