Bulk nanostructured titanium fabricated by hydrostatic extrusion
|Krzysztof Topolski 1, Halina Garbacz 1, Waclaw Pachla 2, Krzysztof J. Kurzydlowski 1|
1. Warsaw University of Technology, Faculty of Materials Science and Engineering (InMat), Wołoska 141, Warszawa 02-507, Poland
This paper is concerned with Hydrostatic Extrusion (HE) as a one of Severe Plastic Deformation (SPD) methods. The material investigated was pure titanium grade 2. Titanium in the form of rod was subjected to multi-stage extrusion with the aim to grain refine and improve the mechanical properties. During subsequent operations of extrusion the rod diameter was gradually reduced. HE is a technique, which permits to accumulate the strain necessary for grain refinement and obtain the nanostructure. The important and basic problem concerned with nanometals after SPD is their relative small volume. HE emerged recently as an effective method of the production of bulk nanostructured metals.
The aim of this study was to optimize the HE process in order to increase the nanostructured titanium rods diameter. The one of the elementary condition of the nanostructure receiving is to accumulate the strain above three (ε > 3). As our studies show, it is possible to obtain nanostructured Ti rods with diameter above 3mm and exceeded 5mm also. The homogeneity of the microstructure and the grain size were examined on transverse and longitudinal cross-sections of the rods. The average grain size on the transverse cross-sections appeared to be below 100nm. The grains observed on the longitudinal cross-sections were elongated and their average grain size exceeded 100nm. According with changes of structure the significant improvement of mechanical properties was observed. The tensile strength was more than 1000MPa and hardness increased over 50%.
This work was carried out within a NANOMET Project financed under the European Funds for Regional Development (Contract No. POIG.01.03.01-00-015/08).
Presentation: Poster at E-MRS Fall Meeting 2009, Symposium H, by Krzysztof Topolski
See On-line Journal of E-MRS Fall Meeting 2009
Submitted: 2009-05-26 18:08 Revised: 2009-08-26 11:12