Superplastic Behavior of a Ti-Al-Mn Alloy

Ti-Al-Mn (OT4-1) alloy is currently being used for aero engine components as well as other aerospace applications by forming through a conventional route which is typically cost, labor and equipment intensive. Titanium alloys such as Ti-6A1-4V is expensive because of the alloying additions like Vanadium are extremely expensive, still this alloy is widely used in aerospace applications by manufacturing the components through superplastic route. The alloy Ti-Al-Mn (made as per the Russian specification, OT4-1) could be a candidate material for replacing the costly Ti-6A1-4V alloys. In the present investigation, tensile tests were carried out on this alloy in the temperature range of 1073 K to 1173 K (800 to 900 degrees C) in the strain rate range of 1x10(-5) to 1x10(-2) s(-1) in order to characterize the high temperature superplastic deformation behavior. A maximum elongation of 450% was observed at 1123 K at an initial strain rate of 5.52x10(-4) s(-1) indicating superplastic behavior of this alloy. From the obtained tensile test results, the optimum superplastic temperature range was identified as 1098 to 1148 K at a strain rate range of 1.38x10(-4) to 1.38x10(-3) s(-1).