The Effect of Low-Temperature Short-Term Annealing on the Microstructure and Properties of Ultrafine-Grained Pure Titanium

Industrial pure titanium was processed through 1–4 passes by equal-channel angular pressing (ECAP), and the processed samples were subsequently short-term annealed for 15 min at 300 °C, to achieve better mechanical properties for industrial applications. The microstructure was analyzed using TEM, EBSD, and XRD observations. The mechanical properties were studied through tensile testing. The TEM and EBSD results showed that the grain size of industrial pure titanium was refined to approximately 420 nm after four passes of ECAP processing, with very little grain growth after annealing. The XRD analysis proved the enhanced basal texture in the subsequent annealed samples. Tensile tests indicated that the strength of the processed sample increased with more ECAP passes and was improved by 39% after four passes compared with the as-received state; in addition, the low-temperature short-term annealing resulted in a further strengthening phenomenon. It was concluded that the strengthening after annealing in industrial pure titanium was likely due to the improved basal texture, resulting in texture strengthening.