Materials Engineering Department
BS in Materials Engineering
Tensile samples of Titanium 6Al-4V (Ti-6Al-4V) were machined from forgings containing rich and poor amounts of beta stabilizers in their compositions. The tensile samples were each heat treated two times. In the first round of heat treatments, the samples were either beta solution treated (BST), or solution treated (ST). Each sample was water quenched with varying quench delays of 10, 20, and 30 seconds. BST treated specimens were then overaged at 1350°F for 2 hours and air cooled (BSTOA); while the ST treated samples were aged at 990°F for 6 hours and air cooled (STA). Following heat treating, the tensile samples were chemically milled to remove the alpha case layer from the surface, and then tensile tested using an Instron Tensile Testing System. Beta stabilizer rich bars that were BSTOA treated with a quench delay of 10 seconds resulted in an average ultimate tensile strength (UTS) of 154 ksi, and average yield strength (YS) of 144 ksi. Beta stabilizer poor, BSTOA treated bars with the same quench delay of 10 seconds, resulted in similar average UTS and YS values of 155 and 145, respectively. Increasing quench delays of BSTOA treated bars to 30 seconds did not alter the resulting average mechanical properties. The beta stabilizer rich bars that were STA treated with a 10 second quench delay resulted in average UTS of 167 ksi and average YS of 154 ksi. Mechanical properties were slightly lowered for beta stabilizer poor, STA treated bars with 10 second quench delays; resulting in average UTS of 166 ksi and YS of 152 ksi. Average properties of both beta rich and beta poor samples that underwent STA heat treatments dropped when the quench delays were 30 seconds.