Investigation on microstructure evolution of hybrid manufactured TC17 titanium alloy during cyclic deformation

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 886; p. 145469
• Main Authors: Shen, Shuxin, He, Bei, Wang, Huaming
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 17.10.2023
• Subjects: Dislocation movement; Hybrid manufacturing; Laser directly energy deposition; Low cycle fatigue; Titanium alloy; Titanium alloy; Hybrid manufacturing; Dislocation movement; Laser directly energy deposition; Low cycle fatigue
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2023.145469

In this work, laser direct energy deposition technology was used to produce hybrid manufactured TC17 titanium alloy with wrought substrate. The cyclic deformation behavior in the total strain range of 1.5%, 2.0%, 2.5%, and 3.0% at ambient temperature and dislocation morphology was investigated. The experimental results show that the three specimens represent cyclic softening when the total strain range is large than 1.5%. All the hybrid manufactured specimens are fractured in the deposition zone and the size of the deformated α phase decreases with increased strain. Slip transfer between α phase and β matrix and a small amount of dislocation tanglement in β matrix was observed in the specimen with strain of 1.5% and cyclic hardening. The dislocation density in β phase increased abruptly when the strain range is 2.5%, which promotes cyclic softening. The heterogeneous deformation between the high and low density dislocation zones formed in the α phase of the cyclic softening samples is the cause of the deformation and fracture of the α phase. The tension-compression asymmetry under forward and reverse loading revealed the Bauschinger effect in specimens with total strain exceeding 1.5%. Dislocation tanglement promoted cyclic softening by increasing the local back stress, at the same time, the back stress helped easier dislocation movement during reverse loading. Meanwhile, dislocation rearrangement and annihilation reduced the friction stress and further accelerate cyclic softening. •LCF properties of hybrid titanium alloys is revealed for the first time.•Critical strain of cyclic softening/hardening of hybrid specimens is obtained.•Dislocation motion mechanism and related internal stress analysis are clarified.