Influence of carbon on aging response and tensile properties of eutectoid beta titanium alloy Ti-13Cr

The influence of carbon addition on the aging response of quenched Ti - 13Cr (wt-%) has been investigated using hardness tests, tensile tests, optical microscopy, X-ray diffraction ( XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It has been found that carbon refines beta grain size, leads to fine and homogenous alpha precipitation and reduces grain boundary alpha. The carbon addition accelerates the rate at which hardening occurs during aging and increases the peak hardness of the aged specimens. A significant improvement in room temperature tensile strength and ductility has also been achieved in the carbon containing alloy after aging at 500 degrees C. The effects of carbon on the aging response appear to be attributed to dislocations introduced by carbides during quenching, elastic strain created in the matrix by carbides and gettering effect of Ti2C carbides. The influence of each of those mechanisms has been demonstrated through experiments and the factors giving rise to the improvements in properties are also discussed in terms of the microstructural observations.