Effect of Hot Isostatic Pressing and Annealing on Microstructure and Tensile Property of Cast TG6 Titanium Alloy

The hot isostatic pressing and annealing treatment at different temperatures were successively conducted on a near-α TG6 titanium alloy by precision casting, and then the microstructure and tensile properties of the alloy in different states was studied. The results show that the microstructure of the cast alloy mainly consisted of Widmanstatten structure, and the shrinkage defect existed in the microstructure; the room temperature tensile strength reached 871.3 MPa, while the elongation was only 0.8%; the shrinkage defect became the crack initiation source. After hot isostatic pressing at 900℃, the shrinkage defect was eliminated, the room temperature elongation increased to 3.7%, and the tensile fracture showed features of quasi cleavage fracture. After annealing at temperatures of 700℃-800℃, β lath in the alloy microstructure was dissolved partially and band-like and granular silicide precipitated, meanwhile the α₂ phase dispersively distributed in the α lath; the room temperature elongation was improved to over 11%, and the tensile fracture at room temperature and 550℃ showed a mixed fracture of cavitation and cleavage, while those at 650℃ and 700℃ showed characteristics of corrosion cracking.