The Role of Titanium Carbides in Forming the Microstructure and Properties of Ti-33Mo-0.2C Alloy

This study presents the characteristics of the Ti-33Mo-0.2C alloy, which belongs to the group of titanium alloys with a stable β phase and contains 0.27 wt% carbon; this is significantly higher than the permissible level for this alloy, which is 0.1 wt%. The Ti-33Mo-0.2C alloy was melted in a vacuum induction furnace with a cold copper crucible and subsequently processed into a 12 mm diameter rod through hot rolling and annealing under standard conditions. The microstructure, as well as the mechanical and physicochemical properties of the Ti-33Mo-0.2C alloy, were compared with those of the Ti-33Mo alloy of a similar chemical composition. The following techniques were used to characterize the microstructure and properties of the alloys: LM; SEM/EDS (WDS); XRD; and mechanical, creep, and corrosion testing. The conducted analyses demonstrated that the addition of approximately 0.2 wt% carbon to the Ti-33Mo alloy leads to the expected improvement in microstructural stability by reducing grain growth and inhibiting the precipitation of the α phase at β grain boundaries. Consequently, a unique simultaneous enhancement of both strength and ductility, with increased creep resistance, is observed while maintaining the excellent corrosion resistance of the investigated alloy. The observed beneficial effects and additional capabilities resulting from the presence of carbon in the investigated alloy justify the conclusion that carbon should no longer be regarded as an undesirable impurity, which stands in contrast to some previous statements.