Effect of annealing temperature on the notch impact toughness of a laser melting deposited titanium alloy Ti–4Al–1.5Mn

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 527; no. 7; pp. 1821 - 1827
• Main Authors: Tian, X.J., Zhang, S.Q., Li, A., Wang, H.M.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 25-03-2010; Elsevier
• Subjects: Anneal; Applied sciences; Exact sciences and technology; Fractures; Impact toughness; Laser melting deposition; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Microstructure; Titanium alloy; Titanium alloy; Impact toughness; Anneal; Laser melting deposition; Microstructure; Scanning electron microscopy; Annealing; Notched test piece; Wrought alloy; Titanium base alloys; Crack propagation; Fracture toughness; Transition metal alloy; Fractography; Impact test
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2009.11.014

A laser deposited near-alpha titanium alloy Ti–4Al–1.5Mn was annealed in the α
+
β phase region at different temperatures in an attempt to obtain novel microstructure. Notch impact toughness of the annealed alloy was evaluated as a function of anneal temperature. Anneal microstructure and fracture surfaces of impact test specimens were characterized by OM and SEM. A unique bi-modal microstructure consisting of coarse crab-claw-like primary α and fine lamellar transformed β was generated by annealing the alloy in the α
+
β region. Area fraction of the crab-claw-like primary α decreased sharply with the increasing anneal temperature. The impact toughness of the as-deposited alloy was equivalent to that of wrought counterpart and was largely improved by annealing in α
+
β region. The unique bi-modal microstructure produced more interfaces which were obstacles for crack propagation, contributing to a higher impact toughness.