Effect of Electric-Current-Assisted Deformation on the Microstructure and Mechanical Properties of Biomedical Grade 4 Titanium with Various Initial Structures
摘要
The microstructure and mechanical properties of commercial-purity grade 4 titanium in coarse-grained (CG) and ultrafine-grained (UFG) states are investigated after tensile deformation accompanied by the action of a pulsed electric current at a current density of 13.4 A/mm2, a duty cycle of 10, and a pulse duration of 500 μs. The manifestation of the electroplastic effect (EPE) in the form of a decrease in the flow stress has been confirmed, and it is most pronounced in the case of UFG titanium. The stability of the microstructure (grain size) during electric-current-assisted deformation has been confirmed by X-ray diffraction, optical microscopy, and transmission electron microscopy. A slight decrease in the microhardness in the area close to a fracture site is also detected for UFG titanium. Z-shaped forming of 2-mm-thick titanium plates using a pulsed electric current at the process parameters used for tension allowed us to eliminate cracking, which was observed in the case of forming without current.