Author
Purcek, G., Yapıcı, Güney Güven, Karaman, I., Maier, H. J.
Publication Date
2011-03-15
Publication Place
-
Elsevier
Subject
Equal-channel angular extrusion/pressing, Grade-2 and grade-4 CP-Ti, Ultrafine-grained materials, Microstructure, Mechanical properties
Type
Periodical
Language
English
Digital
Yes
Manuscript
No
Library
Özyeğin University
Library Asset ID
0921-5093
Record ID
b36d56ed-9d0b-4976-bd6c-a8efe55db430
Library Location
Mechanical Engineering
Date
2011-03-15
Notes
Due to copyright restrictions, the access to the full text of this article is only available via subscription.
Sample Text
Two grades of commercial purity (CP) titanium (grades 2 and 4) were processed using equal-channel angular extrusion (ECAE) at 300 ◦C and 450 ◦C, respectively. The processing temperatures were the minimum temperatures at which eight pass ECAE could be performed without any shear-localization. The coarse-grained (CG) microstructures of as-received grade-2 and grade-4 CP-Ti, with average grain sizes of 110_m and 70_m, respectively, were refined down to sub-micron levels with a mean grain size of about 300nm for both grades after 8 ECAE passes. The ultrafine-grained (UFG) microstructures led to substantial enhancement in strength for both grades. The grade-2 sample showed a more than two fold increase in yield strength (_y), from 307MPa for the as-received one to about 620MPa for the processed samples. The grade-4 CP-Ti exhibited a relatively smaller increase in strength due to the higher processing temperature, and it showed about 50% increase in _y after eight pass ECAE, from 531 to 758 MPa. These strength levels were obtained with high ductility levels of 21% and 25% for UFG grade-2 and grade-4 Ti, respectively. These improvements in mechanical properties are attributed to the substantially refined grain size and increased dislocation density. Grade-4 Ti is stronger than grade-2 because of the higher oxygen content. The higher ductility and significantly higher strain hardening capability of UFG grade-4 Ti, in spite of the similar grain size and microstructure with UFG grade-2 Ti, is also due to the higher impurity content, probably resulting in a higher dislocation storage capability during room temperature deformation, and thus, higher strain hardening capacity. Such properties make UFG grade-4 Ti comparable to the commercial Ti–6Al–4V alloy for biomedical applications without negative effects of the alloying elements on biocompatibility.
DOI
10.1016/j.msea.2010.11.021
Cilt
528
