Achieving high density and controlled microstructure by predicting hot deformation behavior of low-cost powder metallurgy Ti-5553 alloy

Abstract

This study investigates the hot deformation behavior of sintered Ti-5553 alloy with the objective of providing a comprehensive description of its flow behavior, developing a constitutive model, and processing maps. Additionally, the study employs the finite element method (FEM) to simulate the hot forging process and analyze increase in density and microstructure evolution after hot forging trials. The flow curves demonstrated an initial work hardening phenomenon, followed by a softening behavior, and the sensitivity of the investigated material to deformation parameters. The constitutive model demonstrated an accurate prediction of the alloy's behavior, with an average absolute relative error (AARE) of 9.45 % for flow stress at different strain levels. The processing maps have identified three processing windows, which allow for the optimization of parameters for efficient hot deformation. Furthermore, regions exhibiting flow instability have been identified. The microstructure analysis validated the processing windows, revealing the dominant mechanisms of microstructure evolution. The FEM simulations facilitated the design of a hot forging process. The hot forging tests confirmed the successful densification and microstructure evolution as predicted by the processing maps, driven mainly by dynamic recovery (DRV) leading to continuous dynamic recrystallization (CDRX). The hot deformation process resulted in a significant increase in tensile strength, with increase in ultimate tensile strength from 479 ± 124 MPa to 1134 ± 111 MPa. These findings contribute to the understanding of the hot deformation behavior of sintered Ti-5553 alloy, facilitating its effective processing and application in various industrial sectors.

Keywords

• βtitanium alloys
• Powder metallurgy
• Constitutive modeling
• Processing maps
• Finite element method
• Microstructure evolution