| Summary: | 碩士 === 龍華科技大學 === 工程技術研究所 === 101 === Ti-6Al-4V alloy belongs to the α+β bi-phase titanium alloy, which characters in light weight, high strength, low density, low expansion coefficient, non-toxic, nonmagnetic, excellent corrosion resistance and biological compatibility, thus is widely applied to the aerospace, industry, building material, medicine, and consumer goods, etc. The temperature change range of titanium alloy solution heat treatment is from 700℃ to 1100℃; the cooling methods are the furnace cooling, water cooling, and ice cooling, using the test pieces of different solution heat treatment temperatures and different cooling methods, through the thermal dilatometer to discuss the thermal expansion coefficient of different cooling methods after solution heat treatment, and using the universal tensile testing machine and Vickers hardness tester to analyze the mechanical property change of different cooling methods after solution heat treatment, and observing the influence of the microscopic structure and lattice constant by FESEM and XRD from the different cooling methods after solution heat treatment.
The research result shows that, as the ice cooling and water cooling are over cold, the microscopic structure is the martensite structure, while there is the maximum hardness of 960HV in the solution heat treatment 1100℃ by furnace cooling. In the 900℃ solution heat treatment by water cooling, there is the minimum thermal expansion coefficient value of 0.615 (10-6K-1); and in the 800℃ solution heat treatment by ice cooling, there is the strongest tensile strength of 494Kgf, after tempering the strength would slightly increase to 542Kgf . It is significant to improve the mechanical property change of Ti-6Al-4V of different treatment temperatures and cooling methods, and apply to the shaft, supporting seat, and rotating shaft part in the aerospace industry, and the air valve, connecting rod and piston ring, device strap, and pipe fitting joint of vehicle industry, etc.
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