Low-Temperature Sheet Rolling of TiAl Based Alloys

In the present study a considerable decrease in the sheet rolling temperature of gamma-TiAl based alloy was achieved through grain refinement. The use of preforms with homogeneous micro- and submicrocrystalline structure made possible to perform rolling of gamma-TiAl alloy at temperatures as low as 800-1000 degrees C. The decrease in the rolling temperature was directly related to a decrease in the brittle-to-ductile transition temperature. A homogeneous microcrystalline structure was found to be an optimal initial condition for pack rolling at strain rates of about 10(-1) s(-1). Along with retained fine-grained microstructure in the 7 sheets, which provides superior superplastic elongations, the decrease in rolling temperature leads to a substantial decrease in their cost because of energy savings, applicability of cheaper canning materials than those currently being used, less oxidation during preheating and thus a better surface finish.