Microstructure evolution in ultrafine-grained interstitial free steel processed by high pressure torsion

6th International Conference on Nanomaterials by Severe Plastic Deformation

材料科学;化学

Janecek, M.^1 ; Krajnák, T.^1 ; Stráská, J.^1 ; Ciz´ek, J.^1 ; Lee, D.J.^2 ; Kim, H.S.^2 ; Gubicza, J.^3

Charles University in Prague, Ke Karlovu 3, 121 16 Prague 2, Czech Republic^1

Department of Materials Science and Engineering, POSTECH, Pohang 790-784, Korea, Republic of^2

Department of Materials Physics, Eötvös Loránd University, Budapest, Hungary^3

关键词: Dislocation density evolution;    High pressure torsions;    Interstitial free steel;    Micro-structure evolutions;    Microhardness measurement;    Positron annihilation spectroscopy (PAS);    Structure inhomogeneity;    X-ray line profile analysis;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/63/1/012055/pdf
DOI  :  10.1088/1757-899X/63/1/012055

学科分类：材料科学（综合）

来源: IOP

【 摘 要 】

Commercial interstitial free steel was processed by high pressure torsion (HPT) at room temperature up to 5 revolutions. HPT resulted in strong grain refinement. The microstructure after HPT was inhomogeneous with refined grains mainly in regions near the specimen periphery, while coarse only slightly fragmented grains were observed in specimen centre. The microstructure inhomogeneity was continuously smeared out with increasing number of rotations by extending the fine grain region from specimen periphery towards its centre. However, even after 5 revolutions the microstructure remained inhomogeneous characterized by slightly coarser grains in central regions as compared to peripheral regions of the specimen. Positron annihilation spectroscopy (PAS) and X-ray line profile analysis (XLPA) were employed to characterize the structure inhomogeneity in individual specimens. Microstructure and dislocation density evolution were correlated with mechanical properties characterized by a detail microhardness measurement throughout the individual specimens.