THERMO MECHANICAL TREATMENT OF TITANIUM-MOLYBDENUM ALLOYS

Abstract

In the present investigation thermomechanical treatment comprised°cold working of Ti-Mo alloys in the quenched condition from solution treating temperature followed by subsequent aging treatment at 4000 C and 500°C respectively. Two alloys Ti-l0% Mo and Ti-23% Mo are studied with the help of hardness measurements and optical microscopy to observe the mechanical properties as well as the structural changes during this treatment. It was observed that the peak hardness value of either alloy at 5000 C aging temperature is higher than the corresponding value at 400 C. For Ti-23% Mo alloy it is W found that there is variation in the period of hardness peak on aging at either temperature. However, the peak hardness values of Ti-10% Mo alloy are found less than that of Ti-23% Mo alloy for either aging temperature. It is also observed that with increase in prior cold deforma-tion, there is an increase in the hardness peak value upto 50 per cent deformation for TI-10% Mo alloy but for Ti-23% Mo alloy the prior cold deformation upto 30 per cent is effective to increase the peak hardness value. The basis of strengthening effect of thermal treatment is the appea-rance and growth of omega phase, stress induced martensite and the retained beta phase. During this study the presence of omega phase has not experimebtally been observed. U