Metastable Beta Titanium Spring Performance at Elevated Temperature

The application of metastable beta titanium alloy Beta-C™ (Ti-3Al-8V-6Cr-4Mo-4Zr) in spring applications is increasing. A Ti-3Al-8V-6Cr-4Mo-4Zr, or more simply Ti-38-6-44, coil spring can be comparatively smaller than the steel mechanical equivalent on account of its high strength and lower shear modulus. This paper reviews the testing methods and results of load-life fatigue tests performed on helical compression springs at 177 °C with a stress ratio of R=0.456. All springs were compliance tested prior to fatigue testing as a means of measuring the shear modulus. To support spring behavior modeling, the shear modulus was also determined using a torsionally loaded strain gauged specimen tested at room temperature and 177 °C. The thermal expansion behavior was studied from room temperature to above 177 °C.