ABSTRACTEFFECT OF ALLOYING ADDITIONS OF ALUMINIUM AND IRON ON THE CREEPRESISTANCE OF TI-12CR (WT.%)ByHarish Narasimhan ChakravartyTitanium (Ti) and its alloys are among the desired materials for biomaterial, marine, and aerospace applications due to their excellent properties. Metastable beta titanium (β-Ti) alloys exhibit enhanced strengths and hardness values after thermomechanical processing (TMP) due to the presence of omega (ω) and alpha (α) phase precipitates in the beta (β) matrix. Cost is a major driving factor in titanium research. There have been significant efforts to replace high cost alloying elements currently being used in the industry, like V, Sn, Mo, Nb, and Zr, with cheaper ferro-chrome substitutes. The goal going forward for metastable β-Ti alloys is achieving comparable mechanical properties to the commercially used Ti-alloys. β-Ti alloys with the ω-phase usually tend to exhibit higher strengths and hardness values than the ones that do not contain the ω-phase.In this study, the creep properties of three different β-Ti alloys, Ti-12Cr-1Fe-3Al (wt. %), Ti-12Cr-3Al (wt.%), and T-12Cr (wt. %), were experimentally obtained at a temperature of 683K and applied stresses between 200-350 MPa. The relationship between microstructure and creep properties were investigated. X-ray diffractometer (XRD), optical microscope (OM), and scanning electron microscope (SEM) were used to help characterize the microstructure before and after creep deformation. The hardness of alloys increased after heat treatment for 48 hrs at 683 K due to the precipitation of the α and/or the ω phases. The creep tests showed that Ti-12Cr-1Fe-3Al (wt. %) was the most creep resistant and Ti-12Cr (wt. %) was the least creep resistant.
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