Macro-mesoscale microstructural evolution modeling under hot forging of a Ti-17 alloy with a lamellar (α+β) starting microstructure

Microstructural conversion mechanisms under hot forging process (at temperatures ranging from 750 °C to 1050 °C and strain rates ranging from 10–3 s–1 to 1 s–1) of a Ti-5Al-2Sn-2Zr-4Mo-4Cr (Ti-17) alloy with a lamellar starting microstructure were experimentally identified in this work. After that, constitutive formulae for predicting the microstructural evolution were established followed by calculation using finite-element (FEM) analysis. In the α phase, a lamellae kinking is the dominant mode in the higher strain rate region and dynamic globularization frequently occurs at higher temperatures. On the other hand, continuous dynamic recrystallization is the dominant mode below the transition temperature, Tβ (880~890 °C) in the β phase. And, at conditions of lower strain rates and higher temperatures, dynamic recovery tends to be more active. For microstructural prediction, a set of constitutive equations modeling the microstructural evolution and forging properties are established by optimizing the experimental data followed by implementation in the DEFORM-3D software package. Herein, microstructural evolution on dynamic globularization process, dynamic recrystallization behavior are predicted according to both approaches of physical model and artificial neural network model followed by FEM simulation. In these calculated results, there is a satisfactory agreement between the experimental and simulated results, indicating that the established series of constitutive models can be used to reliably predict the properties of a Ti-17 alloy after forging

Macro-mesoscale microstructural evolution modeling under hot forging of a Ti-17 alloy with a lamellar (α+β) starting microstructure

Microstructural conversion mechanisms under hot forging process (at temperatures ranging from 750 °C to 1050 °C and strain rates ranging from 10–3 s–1 to 1 s–1) of a Ti-5Al-2Sn-2Zr-4Mo-4Cr (Ti-17) alloy with a lamellar starting microstructure were experimentally identified in this work. After that, constitutive formulae for predicting the microstructural evolution were established followed by calculation using finite-element (FEM) analysis. In the α phase, a lamellae kinking is the dominant mode in the higher strain rate region and dynamic globularization frequently occurs at higher temperatures. On the other hand, continuous dynamic recrystallization is the dominant mode below the transition temperature, Tβ (880~890 °C) in the β phase. And, at conditions of lower strain rates and higher temperatures, dynamic recovery tends to be more active. For microstructural prediction, a set of constitutive equations modeling the microstructural evolution and forging properties are established by optimizing the experimental data followed by implementation in the DEFORM-3D software package. Herein, microstructural evolution on dynamic globularization process, dynamic recrystallization behavior are predicted according to both approaches of physical model and artificial neural network model followed by FEM simulation. In these calculated results, there is a satisfactory agreement between the experimental and simulated results, indicating that the established series of constitutive models can be used to reliably predict the properties of a Ti-17 alloy after forging

Development of α - β type titanium alloy Ti-4.5Al-2.5Cr-1.2Fe-0.1C-0.3Cu-0.3Ni having good forgeability and machinability

Development of a titanium alloy having excellent hot forgeability and machinability while having the same properties as Ti-64 alloy is effective in reducing the total cost of titanium parts. To develop a new alpha-beta type titanium alloy which has good hot forgeability, machinability and tensile properties equivalent to those of Ti-64 alloy at room temperature, Ti-4.5Al-2.5Cr-1.2Fe-0.1C-nCu-nNi (n=0 to 2) were prepared and evaluated. The new alloy showed tensile properties equivalent to that of Ti-64 alloy at room temperature. On the other hand, the hot deformation stress of new alloy was about 30% lower than that of Ti-64 alloy, and the excellent deformability was confirmed. The addition of Cu and Ni to Ti-4.5Al-2.5Cr-1.2Fe-0.1C alloy suppressed the amount of wear of tool and improved the machinability. Tool life of new alloy machining is extended by about 1.5 times compared to that of Ti-64 alloy. Addition of Cu and Ni is considered to reduce the reactivity between tool and workpiece and improve machinability

Development of α - β type titanium alloy Ti-4.5Al-2.5Cr-1.2Fe-0.1C-0.3Cu-0.3Ni having good forgeability and machinability

Development of a titanium alloy having excellent hot forgeability and machinability while having the same properties as Ti-64 alloy is effective in reducing the total cost of titanium parts. To develop a new alpha-beta type titanium alloy which has good hot forgeability, machinability and tensile properties equivalent to those of Ti-64 alloy at room temperature, Ti-4.5Al-2.5Cr-1.2Fe-0.1C-nCu-nNi (n=0 to 2) were prepared and evaluated. The new alloy showed tensile properties equivalent to that of Ti-64 alloy at room temperature. On the other hand, the hot deformation stress of new alloy was about 30% lower than that of Ti-64 alloy, and the excellent deformability was confirmed. The addition of Cu and Ni to Ti-4.5Al-2.5Cr-1.2Fe-0.1C alloy suppressed the amount of wear of tool and improved the machinability. Tool life of new alloy machining is extended by about 1.5 times compared to that of Ti-64 alloy. Addition of Cu and Ni is considered to reduce the reactivity between tool and workpiece and improve machinability