Fig. 1 Microstructure of the as-forged TNM

Fig. 2 a Schematic diagram of pre-heating, welding and post-heating. b Different zones of the joint. Morphologies of joints under different parameters: c Joint 1, d Joint 2, e Joint 3. f Schematic of the tensile test specimen. g Geometry of the tensile test specimen

Fig. 3 BSE images of the microstructure in the FZ: a Joint 1, b Joint 2, c Joint 3. Euler orientation maps superimposed BC images of the FZ: d Joint 1, e Joint 2, f Joint 3. Pole figures of α2 phase and β0 phase in the FZ: g Joint 1, h Joint 2, i Joint 3

Fig. 4 Phase distribution maps of β0 in the FZ: a Joint 1, b Joint 2, c Joint 3. d Quantitative comparison of the width and width-length ratio of α2/γ lamellar colonies in the FZ of three joints

Fig. 5 Schematic diagram of phase evolution of the FZ during solidification: a liquid phase, b formation of β phase, c nucleation of α grains, d growth of α grains, e formation of α2/γ lamellar colonies and γm at low beam current, f formation of α2/γ lamellar colonies at high beam current, g decomposition of α2/γ lamellar colonies at long post-heating time, h phase diagram of xTi-xAl-4Nb-1Mo-0.1B [26]

Fig. 6 a One α2 grain and three adjacent γ grains. Pole figures of: b, f α2, c, g γ(1), d, h γ(2), e, i γ(3) grains

Fig. 7 Microstructure of the HAZ in Joint 1: a division of different zones, b far-HAZ, c near-HAZ

Fig. 8 a Vickers hardness of joints at different parameters; b comparison of the tensile properties of as-forged TNM alloy and joints at different parameters

Fig. 9 Tensile fracture positions of a Joint 1, b Joint 2, c Joint 3