Influence of low-temperature heat treatment on microstructure and mechanical properties of hydrostatically extruded titanium

Abstract

• Titanium processed by hydroextrusion is a highly nonhomogeneous material. • Continuous dynamic recrystallization operates during the later stages of processing. • Low-temperature heat treatment increases ductility significantly. Subjecting a material processed by a Severe Plastic Deformation method to low-temperature heat treatment has not been the subject of any study so far. Therefore, hydrostatically extruded titanium has been examined within the present work with respect to its mechanical properties and microstructure upon heat treatment at 200 °C. Static tensile tests as well as microstructural analyses with the use of electron backscatter diffraction and transmission electron microscopy have been realized. Even though the material has been annealed, deformation-induced defects were still present within the microstructure what proves that continuous dynamic recrystallization dominates at the later stages of the processing. A significant increase in ductility of a heat-treated material compensates the drop in its tensile properties. Low-temperature annealing might provide an initial solution for resolving the strength-ductility paradox in materials processed by Severe Plastic Deformation techniques.