Details
| Original language | English |
|---|---|
| Pages (from-to) | 2303-2308 |
| Number of pages | 6 |
| Journal | Materials Science and Engineering A |
| Volume | 528 |
| Issue number | 6 |
| Publication status | Published - 13 Nov 2010 |
| Externally published | Yes |
Abstract
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 110μm and 70μm, 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 (σy), 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 σy after eight pass ECAE, from 531 to 758MPa. 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.
Keywords
- Equal-channel angular extrusion/pressing, Grade-2 and grade-4 CP-Ti, Mechanical properties, Microstructure, Ultrafine-grained materials
ASJC Scopus subject areas
- Materials Science(all)
- General Materials Science
- Physics and Astronomy(all)
- Condensed Matter Physics
- Engineering(all)
- Mechanics of Materials
- Engineering(all)
- Mechanical Engineering
Cite this
- Standard
- Harvard
- Apa
- Vancouver
- BibTeX
- RIS
In: Materials Science and Engineering A, Vol. 528, No. 6, 13.11.2010, p. 2303-2308.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Effect of commercial purity levels on the mechanical properties of ultrafine-grained titanium
AU - Purcek, G.
AU - Yapici, G. G.
AU - Karaman, I.
AU - Maier, H. J.
N1 - Funding information: This work was mainly supported by the National Science Foundation – International Materials Institute Program through the grant no. DMR 08-44082 , Office of Specific Programs, Division of Materials Research, Arlington, Virginia. GP would like to acknowledge the support from the Scientific Research Projects of Karadeniz Technical University, Turkey and TUBITAK, Turkey , under 2219-International Postdoctoral Research Scholar Program.
PY - 2010/11/13
Y1 - 2010/11/13
N2 - 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 110μm and 70μm, 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 (σy), 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 σy after eight pass ECAE, from 531 to 758MPa. 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.
AB - 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 110μm and 70μm, 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 (σy), 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 σy after eight pass ECAE, from 531 to 758MPa. 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.
KW - Equal-channel angular extrusion/pressing
KW - Grade-2 and grade-4 CP-Ti
KW - Mechanical properties
KW - Microstructure
KW - Ultrafine-grained materials
UR - http://www.scopus.com/inward/record.url?scp=79151479884&partnerID=8YFLogxK
U2 - 10.1016/j.msea.2010.11.021
DO - 10.1016/j.msea.2010.11.021
M3 - Article
AN - SCOPUS:79151479884
VL - 528
SP - 2303
EP - 2308
JO - Materials Science and Engineering A
JF - Materials Science and Engineering A
SN - 0921-5093
IS - 6
ER -