Heat treatment of TC4 (Ti-6Al-4V)
TC4 (Ti-6Al-4V) is a widely used titanium alloy with excellent mechanical properties such as high strength, high toughness, and corrosion resistance. TC4 is widely used in aerospace, marine and biomedical applications due to its unique properties. When performing heat treatment of TC4, the impact of heat treatment on its microstructure, mechanical properties and corrosion resistance must be considered.
The heat treatment of TC4 includes annealing, solution treatment, aging treatment, and stress relief treatment. Annealing is done to eliminate residual stress and improve the ductility of TC4. Solution treatment homogenizes the microstructure of TC4 by dissolving the second phase and forming a single-phase α matrix. The aging treatment is to precipitate the second phase β phase, thereby enhancing the strength of TC4. Stress relief treatment is to eliminate residual stress generated during heat treatment or mechanical processing.
The annealing process is to heat the TC4 to a temperature between 650°C and 850°C for 1 to 2 hours, and then furnace cool or air cool. The annealing process softens the material, increases its ductility, and reduces residual stresses.
One of the most critical heat treatment steps for TC4 is solution treatment. TC4 is heated to temperatures of 900°C to 950°C for up to four hours and then water quenched. Solution treatment achieves a single-phase alpha matrix, thereby enhancing the toughness and ductility of the material.
The aging treatment is carried out at a temperature ranging from 450°C to 550°C for a maximum of 24 hours. The aging process precipitates beta phase, thereby enhancing the strength of the material. The strength of TC4 increases by about 20% after aging treatment.
The stress relief treatment is performed at temperatures between 500°C and 650°C for up to 2 hours. The stress relief process eliminates residual stresses generated during heat treatment or machining, thereby enhancing the fatigue resistance of the material.
It should be pointed out that the heat treatment of TC4 is a complex process involving annealing, solution treatment, aging, stress relief treatment, etc. The heat treatment process can significantly affect the microstructure, mechanical properties and corrosion resistance of TC4. Therefore, it is very important to select the appropriate heat treatment process according to the application of TC4. With the right heat treatment, TC4 can achieve excellent mechanical properties and corrosion resistance, making it an ideal material for aerospace, marine and biomedical applications.
