Characterization of RHA and Titanium 6-4 Alloys

Rolled Homogeneous Armor (RHA) steel and Titanium 6-4 Alloy are characterized at quasi-static and high strain rates to $\sim $1700/s and high temperatures to $\raise.5ex\hbox{$\scriptstyle 1$}\kern-.1em/ \kern-.15em\lower.25ex\hbox{$\scriptstyle 2$} $ Tm (melting temp). Room temperature stress-strain data show that the strain rate sensitivity of titanium is twice that of RHA. Temperature softening of the two alloys is investigated by performing tests at various temperatures to $\raise.5ex\hbox{$\scriptstyle 1$}\kern-.1em/ \kern-.15em\lower.25ex\hbox{$\scriptstyle 2$} $ Tm. Flow stress of RHA at a strain rate of $\sim $1000/s decreases from about 1500 MPa at 21$^{\circ}$C to 750 MPa at $\raise.5ex\hbox{$\scriptstyle 1$}\kern-.1em/ \kern-.15em\lower.25ex\hbox{$\scriptstyle 2$} $ Tm. In the case of Titanium flow stress decreases from about 1450 MPa to 600 MPa at $\raise.5ex\hbox{$\scriptstyle 1$}\kern-.1em/ \kern-.15em\lower.25ex\hbox{$\scriptstyle 2$} $ Tm. Two alloys are also characterized in the torsion mode to investigate their shear response. Shear stress -- strain data are analyzed to correlate to the tension data for both the alloys.