Effect of Elevated Temperature Exposure on Mechanical Properties of Ti-6242S

Ti-6Al-2Sn-4Zr-2Mo-0.1Si (Ti-6242S) is a common near-alpha titanium alloy that is used for elevated temperature applications in compressor sections of turbine engines and hot airframe skin components. Exposure to an air environment at high temperatures leads to elevated concentrations of oxygen in exposed surfaces and, in most cases, a degradation in mechanical properties. In this study, tensile and fatigue properties were investigated for material exposed at 650°C (1200°F) for various times up to 420 hours as well as material in the received condition.  Elevated temperature exposure adversely effected tensile elongation and ultimate tensile strength and was detrimental to fatigue crack initiation resistance. Clear correlation was shown between exposure time at 650°C and poor fatigue crack initiation resistance with exposures as short as nine hours revealing a greater than 50% drop in fatigue life over as received material. Results of the experimental program and the mechanisms responsible for the degradation in tensile and fatigue properties will be discussed.