Hot stamping of titanium alloys
File(s)
Author(s)
Kopec, Mateusz
Type
Thesis
Abstract
Demand for low density and high strength materials in the aviation sector has expanded greatly
due to ambitious carbon emission and fuel consumption targets. In order to meet these targets,
manufacturers have focused on weight reduction via the use of lightweight materials. In the
aerospace sector, high strength structural components are made from titanium alloys. However,
the forming of complex-shaped components from titanium alloys is time, energy and cost
intensive. One promising solution to overcome these difficulties proposed in the literature is
using the hot stamping process to form complex-shaped components from sheet metal with
cold dies, and rapidly quenching the workpiece in the dies simultaneously. The hot stamping
process promises to reduce the tool wear commonly found in conventional hot forming
processes and be an overall more efficient and economical process when compared to
conventionally used isothermal hot forming techniques. A novel hot stamping process for
titanium alloys using cold forming tools and a hot blank was studied systematically in this thesis.
This work aims to investigate the microstructural evolution and flow behavior of a titanium
alloy (Ti6Al4V) under hot stamping conditions experimentally, and to model these parameters
using the constitutive equations proposed. The material behavior was modelled using
mechanism-based viscoplastic constitutive equations to replicate the material response of a
two-phase titanium alloy Ti6Al4V under hot stamping conditions. Finally, the developed
model's accuracy was validated by comparing to experimental uniaxial tensile tests and
microstructural maps of the deformed alloy. Microstructural analysis revealed that the heating
and soaking conditions are vital to the microstructure and post-form strength, whereas the
plastic deformation during the hot stamping only has a negligible effect on both
recrystallization and phase transformation due to the very short deformation time. The
developed material model was implemented into the Finite Element (FE) simulation to study
the deformation characteristics during the hot stamping process. The verified simulation data
were analysed through a novel hot stamping technique with good agreements achieved between
the predicted and experimental results. A complex shaped wing stiffener panel component was
successfully formed from TC4 titanium alloy, demonstrating the great potential of investigated
technology in forming complex shaped titanium alloys components. Finally, Fast light Alloys
Stamping Technology (FAST) is proposed for titanium alloys, where fast heating to a twophase titanium alloy sheet with equiaxed microstructure is employed.
due to ambitious carbon emission and fuel consumption targets. In order to meet these targets,
manufacturers have focused on weight reduction via the use of lightweight materials. In the
aerospace sector, high strength structural components are made from titanium alloys. However,
the forming of complex-shaped components from titanium alloys is time, energy and cost
intensive. One promising solution to overcome these difficulties proposed in the literature is
using the hot stamping process to form complex-shaped components from sheet metal with
cold dies, and rapidly quenching the workpiece in the dies simultaneously. The hot stamping
process promises to reduce the tool wear commonly found in conventional hot forming
processes and be an overall more efficient and economical process when compared to
conventionally used isothermal hot forming techniques. A novel hot stamping process for
titanium alloys using cold forming tools and a hot blank was studied systematically in this thesis.
This work aims to investigate the microstructural evolution and flow behavior of a titanium
alloy (Ti6Al4V) under hot stamping conditions experimentally, and to model these parameters
using the constitutive equations proposed. The material behavior was modelled using
mechanism-based viscoplastic constitutive equations to replicate the material response of a
two-phase titanium alloy Ti6Al4V under hot stamping conditions. Finally, the developed
model's accuracy was validated by comparing to experimental uniaxial tensile tests and
microstructural maps of the deformed alloy. Microstructural analysis revealed that the heating
and soaking conditions are vital to the microstructure and post-form strength, whereas the
plastic deformation during the hot stamping only has a negligible effect on both
recrystallization and phase transformation due to the very short deformation time. The
developed material model was implemented into the Finite Element (FE) simulation to study
the deformation characteristics during the hot stamping process. The verified simulation data
were analysed through a novel hot stamping technique with good agreements achieved between
the predicted and experimental results. A complex shaped wing stiffener panel component was
successfully formed from TC4 titanium alloy, demonstrating the great potential of investigated
technology in forming complex shaped titanium alloys components. Finally, Fast light Alloys
Stamping Technology (FAST) is proposed for titanium alloys, where fast heating to a twophase titanium alloy sheet with equiaxed microstructure is employed.
Version
Open Access
Date Issued
2020-05
Date Awarded
2020-09
Copyright Statement
Creative Commons Attribution NonCommercial NoDerivatives Licence
Advisor
Wang, LiLiang
Lin, Jianguo
Sponsor
Aviation Industry Corporation of China (Firm)
Publisher Department
Mechanical Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)