The relationship between the microstructures and the mechanical properties of solution-treated SP-700 titanium alloys, as obtained with different cooling rates, was investigated. The results indicate that the water-quenched alloy contains the primary (p), ”-martensite and residual (r) phases. Aging heat treatment can convert both ”-martensite and the r phases to the fine-grained + equilibrium phases, resulting in a significant increase in tensile strength and hardness. Both the air-cooled and furnace-cooled alloys consist of the p, and phases. The air-cooled alloy containing the fine-grained phase has relatively higher hardness. Aging heat treatment causes only a slight enhancement in tensile properties because it cannot convert the phases in both alloys. Stress-induced martensitic phase transformation occurs in the water-quenched alloy under applied stress, after which the alloy exhibits higher tensile strength, higher ductility, and lower yield strength.
Nieh, Jo-Kuang; Wu, Chih-Ting; Chen, Yen-Lin; Wei, Chao-Nan; and Lee, Sheng-Long
"EFFECT OF COOLING RATE DURING SOLUTION HEAT TREATMENT ON THE MICROSTRUCTURE AND MECHANICAL PROPERTIES OF SP-700 TITANIUM ALLOYS,"
Journal of Marine Science and Technology: Vol. 24:
2, Article 4.
Available at: https://jmstt.ntou.edu.tw/journal/vol24/iss2/4