Superplastic forming of Ti6Al4V alloy using ZrO2-TiO2 ceramic die with adjustable linear thermal expansion coefficient
(National Key Laboratory for Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001, China)
Abstract: Firstly, the relation between the coefficient of thermal expansion(CTE) and the volume fraction of TiO2 was investigated, and also the influence of relative density of ceramic on the CTE was studied. The results show that the volume fraction of TiO2 and the relative density both make influence on the CTE of ZrO2-TiO2 ceramic. According to the results, the ZrO2-TiO2 (volume fraction of TiO2 is 27%) ceramic die with the similar CTE (8.92×10−6 ℃−1) to Ti6Al4V was fabricated. Secondly, to evaluate the dimensional accuracy of the workpiece superplastically formed, the Ti6Al4V impression experiment was performed. The result shows that the dimensional inaccuracy of workpiece is 0.003. Thirdly, in order to evaluate the practicability, the experiment of superplastic forming Ti6Al4V using ZrO2-TiO2 cylinder ceramic die was carried out. The Ti6Al4V cylinder shows good shape retention and surface quality, and high dimensional accuracy. The ceramic dies seem to be adequate for superplastic forming the high accuracy Ti6Al4V, and the trials have confirmed the potential of the ZrO2-TiO2 ceramic die.
Key words: Ti6Al4V; superplastic forming; ceramic die; linear coefficient of thermal expansion