High-speed superplastic formability and deformation mechanisms of Ti6Al4V sheets

Abstract

A low deformation rate is a significant disadvantage in the high-temperature superplastic forming (SPF) process, and grain boundary sliding (GBS) and creep mechanisms occur during deformation. The high-speed SPF method is being investigated to eliminate this disadvantage. Also, the high-speed SPF of Ti6Al4V (Ti64) sheet material and the effects of deformation mechanisms on formability were investigated experimentally. SPF and high-speed SPF treatments were carried out with hot tensile tests at specific temperatures, which in turn are 670, 770, 870, 890, and 910 °C at deformation rates of 10-2 to 10-3 s-1 and without a protective atmosphere. The deformation mechanisms in the microstructure of the samples were investigated by electron microscopy. In experimental studies, it has been observed that GBS deformation occurs at 870 °C and positively affects formability with 1489% elongation at 870 °C and 701% at 910 °C. While the effects of these deformation mechanisms were not observed clearly under 870 °C, it was observed that the superplastic formability had a decreasing trend at 890 °C and 910 °C with the effect of creep deformation.