Symbol/Acronym	Full name	Symbol/Acronym	Full name
SPF	Superplastic forming	ε	True strain
CE	Constitutive equations	$\dot{\epsilon }$	Deformation strain rate (s-1)
R	correlation coefficient	T	Deformation temperature (°C)
AARE	mean absolute relative error	m	Strain rate sensitivity index
RMSE	root mean square error	GBS	Grain boundary sliding
ANN	artificial neural network	A, β, n1, n2 and α	Material constants
α	Titanium alpha-phase (HCP)	Q	Effective activation energy (kJ/mol)
β	Titanium beta phase (BCC)	R	gas constant 8.314 J/(mol·K).
SEM	Scanning electron microscope	α′	Returned beta phase
LAGB	low-angle grain boundary	EBSD	Electron backscatter diffraction
σ	Flow stress (MPa)	HAGB	high-angle grain boundary