Details
| Original language | English |
|---|---|
| Pages (from-to) | 4194-4206 |
| Number of pages | 13 |
| Journal | Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science |
| Volume | 44 |
| Issue number | 9 |
| Publication status | Published - 11 May 2013 |
| Externally published | Yes |
Abstract
The stretch formability of ultrafine-grained (UFG) interstitial-free steel (IF-steel) produced by equal-channel angular extrusion/pressing (ECAE/P) via various strain paths was investigated with a miniaturized Erichsen test. A coarse-grained (CG) sample demonstrated high formability with an Erichsen index (EI) of 4.5 mm. Grain refinement by ECAE decreased the formability, but increased the required punch load (F EI) depending on the applied strain paths. The EI values were 0.35, 2.90, 3.91 mm for 8A-, 8Bc-, 8C-processed samples, respectively. Decrease in the biaxial stretch formability was attributed to the limited strain-hardening capacity of the UFG microstructure. Also, the grain morphology of the UFG microstructure was found to be very influential on stretch formability. Heavily elongated grain morphology in the 8A-processed microstructure resulted in the lowest formability due to the increased cracking tendency through elongated grain boundaries. However, the UFG microstructures with equiaxed grains obtained after 8C and 8Bc ECAE resulted in better formability compared to 8A. The UFG microstructure reduced the roughness (orange peel effect) of the free surface of the biaxial stretched samples by decreasing the non-uniform grain flow leading to the so-called orange peel effect. It should be noted that the strength and ductility values gained from uniaxial tensile tests are not comparable directly to the EI and F EI values determined from the Erichsen tests. Finally, it is important to emphasize that the UFG microstructure produced by a suitable strain path leading to equiaxed grains below 1 μm could be highly deformed even under multiaxial stress conditions.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Condensed Matter Physics
- Engineering(all)
- Mechanics of Materials
- Materials Science(all)
- Metals and Alloys
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In: Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science, Vol. 44, No. 9, 11.05.2013, p. 4194-4206.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Formability of Ultrafine-Grained Interstitial-Free Steels
AU - Saray, Onur
AU - Purcek, Gencaga
AU - Karaman, Ibrahim
AU - Maier, Hans J.
N1 - Funding information: This study was mainly supported by the Scientific and Technological Research Council of Turkey (TUBITAK) under Grant No: 107M618. O. Saray acknowledges the support from the International Doctoral Research Scholar Program of Higher Education Council (YOK) of Turkey. I. Karaman acknowledges the support from the U.S. National Science Foundation, Division of CMMI, Grant 0900187, and the International Materials Institute Program through Grant DMR 08-44082, Office of Specific Programs, Division of Materials Research. H.J. Maier acknowledges support by Deutsche Forschungsgemeinschaft. The authors would like to thank Eregli Iron and Steel (ERDEMIR), Inc., Zonguldak, Turkey, for their support in kindly supplying the initial materials.
PY - 2013/5/11
Y1 - 2013/5/11
N2 - The stretch formability of ultrafine-grained (UFG) interstitial-free steel (IF-steel) produced by equal-channel angular extrusion/pressing (ECAE/P) via various strain paths was investigated with a miniaturized Erichsen test. A coarse-grained (CG) sample demonstrated high formability with an Erichsen index (EI) of 4.5 mm. Grain refinement by ECAE decreased the formability, but increased the required punch load (F EI) depending on the applied strain paths. The EI values were 0.35, 2.90, 3.91 mm for 8A-, 8Bc-, 8C-processed samples, respectively. Decrease in the biaxial stretch formability was attributed to the limited strain-hardening capacity of the UFG microstructure. Also, the grain morphology of the UFG microstructure was found to be very influential on stretch formability. Heavily elongated grain morphology in the 8A-processed microstructure resulted in the lowest formability due to the increased cracking tendency through elongated grain boundaries. However, the UFG microstructures with equiaxed grains obtained after 8C and 8Bc ECAE resulted in better formability compared to 8A. The UFG microstructure reduced the roughness (orange peel effect) of the free surface of the biaxial stretched samples by decreasing the non-uniform grain flow leading to the so-called orange peel effect. It should be noted that the strength and ductility values gained from uniaxial tensile tests are not comparable directly to the EI and F EI values determined from the Erichsen tests. Finally, it is important to emphasize that the UFG microstructure produced by a suitable strain path leading to equiaxed grains below 1 μm could be highly deformed even under multiaxial stress conditions.
AB - The stretch formability of ultrafine-grained (UFG) interstitial-free steel (IF-steel) produced by equal-channel angular extrusion/pressing (ECAE/P) via various strain paths was investigated with a miniaturized Erichsen test. A coarse-grained (CG) sample demonstrated high formability with an Erichsen index (EI) of 4.5 mm. Grain refinement by ECAE decreased the formability, but increased the required punch load (F EI) depending on the applied strain paths. The EI values were 0.35, 2.90, 3.91 mm for 8A-, 8Bc-, 8C-processed samples, respectively. Decrease in the biaxial stretch formability was attributed to the limited strain-hardening capacity of the UFG microstructure. Also, the grain morphology of the UFG microstructure was found to be very influential on stretch formability. Heavily elongated grain morphology in the 8A-processed microstructure resulted in the lowest formability due to the increased cracking tendency through elongated grain boundaries. However, the UFG microstructures with equiaxed grains obtained after 8C and 8Bc ECAE resulted in better formability compared to 8A. The UFG microstructure reduced the roughness (orange peel effect) of the free surface of the biaxial stretched samples by decreasing the non-uniform grain flow leading to the so-called orange peel effect. It should be noted that the strength and ductility values gained from uniaxial tensile tests are not comparable directly to the EI and F EI values determined from the Erichsen tests. Finally, it is important to emphasize that the UFG microstructure produced by a suitable strain path leading to equiaxed grains below 1 μm could be highly deformed even under multiaxial stress conditions.
UR - http://www.scopus.com/inward/record.url?scp=84881085528&partnerID=8YFLogxK
U2 - 10.1007/s11661-013-1781-0
DO - 10.1007/s11661-013-1781-0
M3 - Article
AN - SCOPUS:84881085528
VL - 44
SP - 4194
EP - 4206
JO - Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
JF - Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
SN - 1073-5623
IS - 9
ER -