Murugesan Jayaprakash

Effect of Zr Addition on High Temperature Mechanical Properties of Near Alpha Ti-Al-Zr-Sn Based Alloy

Titanium (Ti) alloys are widely used in aerospace industries successfully up to 600°C. Increasing the operating temperature and performance of these alloys would be very useful for fuel economy. Numerous numbers of research works has been focused on the improvement of the high temperature performances of Ti alloys. It has been well known that Zirconium (Zr) is one of the important solid-solution strengthener in Ti-alloys. In the present study, the effect of Zr addition on the microstructure and mechanical properties of the near–α Ti-Al-Zr-Sn based alloys has been investigated.The compression test results showed that Zr addition significantly improves both room temperature and high temperature strength. The results obtained were explained based on the microstructural observation, room temperature and high temperature compressive tests.

Fretting Fatigue Behaviour of 12-Cr Steels and Strength Prediction

In the present study fretting fatigue behaviour of 12-Cr steels at 300°C has been investigated under three different contact pressures. For comparisons fretting fatigue behaviour of 12-Cr steels at room temperature has also been investigated. The result showed that with an increase in contact pressure and temperature, the fretting fatigue significantly reduces. Finite element analyses were carried out to evaluate the stress distribution (tangential stress and compressive stress) at the contact during fretting fatigue. Tangential stress range – compressive stress range diagram (TSR-CSR diagram) were constructed for 12-Cr steel at room temperature and at 300°C. Then, a generalized TSR-CSR diagram to predict fretting fatigue strength of 12-Cr steel regardless of contact pressure and temperature was constructed.