EFFECT OF COOLING RATE DURING SOLUTION HEAT TREATMENT ON THE MICROSTRUCTURE AND MECHANICAL PROPERTIES OF SP-700 TITANIUM ALLOYS

Authors

Jo-Kuang Nieh, Department of Mechanical Engineering, National Central University, Taoyuan, Taiwan, R.O.C
Chih-Ting Wu, Department of Vehicle Engineering, Army Academy, Taoyuan, Taiwan, R.O.C
Yen-Lin Chen, Institute of Materials Science and Engineering, National Central University, Taoyuan, Taiwan, R.O.C
Chao-Nan Wei, Materials and Electro-Optics Research Division, National Chung-Shan Institute of Science and Technology, Taoyuan, Taiwan, R.O.C.
Sheng-Long Lee, Department of Mechanical Engineering, National Central University,Taoyuan, Taiwan, R.O.C Institute of Materials Science and Engineering, NationalCentral University,Taoyuan, Taiwan, R.O.C.

Abstract

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.

Recommended Citation

Nieh, Jo-Kuang; Wu, Chih-Ting; Chen, Yen-Lin; Wei, Chao-Nan; and Lee, Sheng-Long (2016) "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: Iss. 2, Article 4.
DOI: 10.6119/JMST-015-0409-1
Available at: https://jmstt.ntou.edu.tw/journal/vol24/iss2/4