Forging property, processing map, and mesoscale microstructural evolution modeling of a Ti-17 alloy with a lamellar (α plus β) starting microstructure

This work identifies microstructural conversion mechanisms during hot deformation (at temperatures ranging from 750 degrees C to 1050 degrees 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 and establishes constitutive formulae for predicting the microstructural evolution using finite-element analysis. In the a phase, lamellae kinking is the dominant mode in the higher strain rate region and dynamic globularization frequently occurs at higher temperatures. In the beta phase, continuous dynamic recrystallization is the dominant mode below the transition temperature, T-beta (880 similar to 890 degrees C). Dynamic recovery tends to be more active at conditions of lower strain rates and higher temperatures. At temperatures above T-beta, continuous dynamic recrystallization of the beta phase frequently occurs, especially in the lower strain rate region. A set of constitutive equations modeling the microstructural evolution and processing map characteristic are established by optimizing the experimental data and were later implemented in the DEFORM-3D software package. 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 in the (alpha+beta) region.