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Max Planck Institute for Iron Research
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Papers by m shaban
Journal of Iron and Steel Research International, 2011
Grain refinement in a plain carbon steel under intercritical warm deformation was studied by tors... more Grain refinement in a plain carbon steel under intercritical warm deformation was studied by torsion testing. Based on the experimental results. tbp warm flow behaviour and microstructural evolution of ferrite were researched with particular emphasis on the effect of the strain rate in controlling the grain refinement mechanism of ferrite. The deformed microstructures were investigated at various strain rates using optical microscopy and electron back-scattered diffraction (EBSD). The EBSD observations indicate that an increase in the strain rate leads to the development of new fine ferrite grains with high angle boundaries. Furthermore, it shows that the annihilation of dislocations occurs more readily at lower strain rate. The elongated ferrite grains continuously dynamically recrystallize to form the equiaxed fine ferrite grains. Thereby, the aspect ratio of elongated grains decreases with increasing the strain rate. Furthermore, the peak stress and steady state stress of ferrite both increase with increasing strain rate. Based on the study, the effect of strain rate on the development of fine ferrite grains during continuous dynamic recrystallization of ferrite was analyzed in detail.
Journal of Iron and Steel Research, International, 2013
A combination of extrusion and equal channel angular pressing (E C A P) was used to deform a plai... more A combination of extrusion and equal channel angular pressing (E C A P) was used to deform a plain low carbon steel. This process consists of two successive deformations by extrusion and ECAP in a single die (Ex-ECAP). Cylindrical samples were heated to predefined temperatures (650 and 850-C) and then pressed through a die channel with crosshead speed of 10 m m / s. Microstructure and resultant mechanical properties of processed mate rial were studied. The results showed that pressing temperature has a significant effect on the resultant microstruc ture. While at 650 'C , the cold worked structure with elongated ferrite grains were obtained, and at 850 "C the mi crostructure consisted of elongated ferrite grains and very fine grains at their boundaries as a consequence of continu ous dynamic recrystallization (CDRX) of ferrite phase. Also at 850 *C , a particular microstructure consisted of cold worked ferrite and static recrystallized grains on shear bands was obtained.
Atherosclerosis Supplements, 2006
Proceedings Sixth International Conference on Tools with Artificial Intelligence. TAI 94
By utilizing structure sharing among its parse trees, a GB parser can increase its efficiency dra... more By utilizing structure sharing among its parse trees, a GB parser can increase its efficiency dramatically. Using a GB parser which has as its phrase structure recovery component an implementation of Tomita's natural language algorithm (M. Tomita, 1986), we investigate how a GB parser can preserve the structure sharing output by Tomita's algorithm. We give some details of the structure-sharing parser currently under construction. Our approach to preserving sharing within a shared-packed forest is applicable not only to GB parsing, but anytime we want to preserve structure sharing in a parse forest in the presence of features.<<ETX>>
Journal of Iron and Steel Research International, 2011
Grain refinement in a plain carbon steel under intercritical warm deformation was studied by tors... more Grain refinement in a plain carbon steel under intercritical warm deformation was studied by torsion testing. Based on the experimental results. tbp warm flow behaviour and microstructural evolution of ferrite were researched with particular emphasis on the effect of the strain rate in controlling the grain refinement mechanism of ferrite. The deformed microstructures were investigated at various strain rates using optical microscopy and electron back-scattered diffraction (EBSD). The EBSD observations indicate that an increase in the strain rate leads to the development of new fine ferrite grains with high angle boundaries. Furthermore, it shows that the annihilation of dislocations occurs more readily at lower strain rate. The elongated ferrite grains continuously dynamically recrystallize to form the equiaxed fine ferrite grains. Thereby, the aspect ratio of elongated grains decreases with increasing the strain rate. Furthermore, the peak stress and steady state stress of ferrite both increase with increasing strain rate. Based on the study, the effect of strain rate on the development of fine ferrite grains during continuous dynamic recrystallization of ferrite was analyzed in detail.
Journal of Iron and Steel Research, International, 2013
A combination of extrusion and equal channel angular pressing (E C A P) was used to deform a plai... more A combination of extrusion and equal channel angular pressing (E C A P) was used to deform a plain low carbon steel. This process consists of two successive deformations by extrusion and ECAP in a single die (Ex-ECAP). Cylindrical samples were heated to predefined temperatures (650 and 850-C) and then pressed through a die channel with crosshead speed of 10 m m / s. Microstructure and resultant mechanical properties of processed mate rial were studied. The results showed that pressing temperature has a significant effect on the resultant microstruc ture. While at 650 'C , the cold worked structure with elongated ferrite grains were obtained, and at 850 "C the mi crostructure consisted of elongated ferrite grains and very fine grains at their boundaries as a consequence of continu ous dynamic recrystallization (CDRX) of ferrite phase. Also at 850 *C , a particular microstructure consisted of cold worked ferrite and static recrystallized grains on shear bands was obtained.
Atherosclerosis Supplements, 2006
Proceedings Sixth International Conference on Tools with Artificial Intelligence. TAI 94
By utilizing structure sharing among its parse trees, a GB parser can increase its efficiency dra... more By utilizing structure sharing among its parse trees, a GB parser can increase its efficiency dramatically. Using a GB parser which has as its phrase structure recovery component an implementation of Tomita's natural language algorithm (M. Tomita, 1986), we investigate how a GB parser can preserve the structure sharing output by Tomita's algorithm. We give some details of the structure-sharing parser currently under construction. Our approach to preserving sharing within a shared-packed forest is applicable not only to GB parsing, but anytime we want to preserve structure sharing in a parse forest in the presence of features.<<ETX>>