Constitutive equation and hot processing map of TA15 titanium alloy

Abstract

The stress-strain curves of TA15 titanium alloy at 750∼950°C and 0.001∼1 s −1 were obtained by hot compression with Gleeble-1500D. Based on the compression experimental data of TA15 titanium alloy, the Johnson-Cook high temperature thermal deformation constitutive equation was established. By calculating the constitutive equation, the flow stress was compared with the measured stress-strain curve, and the accuracy of the equation was verified. Then, based on the theory of hot processing map of dynamic materials, the hot processing map is drawn when the strain is 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6. The reasonable range of hot processing map of TA15 titanium alloy was determined. When the temperature is between 750°C-875°C, the power dissipation factor decreases with increasing strain rate. The maximum power dissipation is distributed between 825°C-950°C. This indicates that recrystallization occurred within this range. The safe zone is mainly concentrated in the temperature range of 885°C-950°C, the strain rate is less than 0.1 s −1 . It can be seen that instability does not occur in the high temperature and low strain region. Therefore, at 885 T 950°C, 0.001  e 0.1 s −1 or 800 T 875°C, 0.001  e 0.002 s −1 , it is reasonable to perform high temperature deformation on TA15 titanium alloy. experiments, optical microscopy (OM), electron backscatter diffraction (EBSD), and quantitative analysis were used to study the β thermal deformation behavior of TA15 titanium alloy. Thermal simulation compression experiments, optical microscope (OM), and electronic backscatter diffraction Technology (EBSD) and Quantitative Analysis Study the β Hot Deformation Behavior of TA15 Titanium Alloy ,analyzed the influence of deformation temperature, strain rate and deformation on its flow stress and microstructure; Xi et al [12]. Studied the evolution of the microstructure of TA15 titanium alloy after superplastic deformation and the effect of deformation conditions on the superplastic deformation behavior; Xu et al [13]. Experimentally studied the compression deformation behavior and microstructure characteristics of TA15 titanium alloy under the conditions of strain rate 0.01∼20 s −1 and deformation temperature 850∼1050°C, TA15 constitutive equation was derived using Arrhenius hyperbolic sine function model. Based on the dynamic material model, the hot processing map of the alloy at the true strain of 0.1∼0.7 was established. The hot processing map is very practical for studying the flow stress of materials and optimizing the parameters of heat treatment, and its practicality has been used in Bstmuf601 superalloy [14], medium and high carbon high silicon bainite steel [15], as-cast 6Mo super austenitic stainless [16], Sa508-Iv steel [17], 34CrNiMo6 steel [18], Fe-Mn-Al-C steel [19] and other materials have been proven.Constitutive model is the key to the relationship between reaction rheological behavior and metal and alloy parameters [20][21][22][23]. Therefore, the flow stress, constitutive equation, hot processing...

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