Formability of ultra-fine grained metallic materials
- Autores: Eva Cristina Moreno Valle
- Directores de la Tesis: Ilshat Sabirov (dir. tes.)
- Lectura: En la Universidad Carlos III de Madrid ( España ) en 2014
- Idioma: inglés
- Tribunal Calificador de la Tesis: José Manuel Torralba Castelló (presid.), David Morris (secret.), Anton Hohenwarter (voc.)
- Materias:
- Enlaces
- Tesis en acceso abierto en: e-Archivo
- Resumen
Ultra-fine grained (UFG) metallic materials have been a hot topic in materials science for the last 25 years. There is a significant body of research showing that the UFG materials have very high mechanical strength, but their commercialisation is limited due to their low uni-axial tensile ductility. The main objective of this PhD thesis is to study the bi-axial stretching formability of the UFG metallic materials. It is demonstrated that there is a significant effect of the stress state (stress triaxiality) on mechanisms operating during plastic deformation in the UFG commercially pure (CP) Cu and the deformation mechanisms are determined by the stress state. The microstructure of the UFG CP Cu can be designed in such a way so as to show very high formability, even exceeding that of its coarse-grained counterpart. The effect of metallographic and crystallographic texture on the bi-axial stretching formability of the UFG CP Ti has been analysed. It is shown that the UFG CP Ti can show bi-axial stretching formability sufficient for metalforming operations. Coarse dispersoids and fractured particles in the Al 2024 alloy significantly limit its formability, acting as sites for the formation of cracks leading to sample failure at the early stages of deformation. Based on the analysis of the experimental results, a general recipe to improve formability of the UFG metallic materials is proposed. ------------------------------------------------------------------------------------
