Utilizing a Meso Scale Limited Dome Test to Study the Effect of Strain Rate on the Formability of Commercial Pure Titanium Grade Two Foil

Abstract

Due to its hexagonal close-packed (HCP) crystal structures and limited slipping systems, commercial pure titanium (CP Ti) has a relatively low ductility at room temperature. In order to understand the effect of strain rate on formability of the as-received tempered CP Ti grade 2 foils with thickness of 38µm, a series of meso-limited dome height (meso-LDH) tests were designed and conducted at three punch speeds (0.01mm/sec, 12m/sec and 17m/sec) without lubricant at room temperature. The forming limit curves of the foil at three different punch speeds were obtained, and can be used right away for product design, process design and development, die design, and simulations etc. As discovered in this experimental study, the reasons why increasing strain rate can improve the formability are: n value increases with increasing strain rate, the temperature of part increases rapidly due to adiabatic effect, and the negative influence of friction can be reduced.