Influence of Low-Temperature Heat Treatments on the Microstructural Heterogeneity Induced by ECASE in Commercially Pure Titanium Grade 2

Abstract

Commercially pure grade 2 titanium (CP Ti G2) is an attractive alternative for biomedical applications due to its high corrosion resistance and excellent biocompatibility. However, its mechanical properties and wear resistance are insufficient for certain applications. This work analyzes the effect of heat treatments on the microstructural heterogeneity induced by Equal Channel Angular Sheet Extrusion (ECASE). For this purpose, CP Ti G2 sheets were subjected to severe plastic deformation by one ECASE pass and subsequently heat treated at 250 °C and 300 °C for 10 and 40 minutes. Characterization was carried out by Vickers microhardness testing at three locations through the sample thickness: the center and the surfaces in contact with the angular channel of the tool used to deform the material. In addition, microstructural analysis was performed by electron backscatter diffraction (EBSD). The results show that ECASE processing generates a heterogeneous hardness distribution, with higher values in the surface regions. Heat treatments modify this heterogeneity, increasing the heterogeneity index up to a maximum value of 15% for the condition treated at 300 °C for 10 minutes, while the treatment at 300 °C for 40 minutes produced the highest surface hardness. These results indicate that low-temperature heat treatments allow the mechanical response of the previously deformed material to be modified, constituting a promising strategy for optimizing its properties without altering its chemical composition.