الفهرس 
ch 1IntroductionOnly 14 pages are availabe for public view
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Abstract
Si-Steel thin sheets are usually used for electric power transformation. The sheets are considered as a value-added product for the production sites as they are not need either special facilities or sophisticated technology. However, the grand price is feasible with respect to the processing costs. The present work is dealing with development of 2% Si-steel alloy. Furtherly, the alloy contains 0.05 % C as well as 0.85 % Al. The alloy under investigation is used for electrical transformation purposes. The alloy was prepared by melting and casting to Y-block ingots. Suitable specimens were machined to suit the dilatation investigation. A heating (expansion) - cooling (contraction) cycle was executed to detect the α, α+γ and γ critical transformation temperatures at the inflection points of the dilatation curve. On heating, primary α was detected at a temperature range room temperature (RT) - 687 ℃. The domain of α+γ was then detected in the range 687 -746 ℃. γ-phase exists as a closed γ loop at the range 746 -1043 ℃. The α+γ phase exists again at a temperature range 1043-1105 ℃ and followed by secondary α-phase at temperature higher than 1105 °C. A physical simulation of thermo-mechanical processing on the as-cast alloy was carried out by using the thermo-mechanical simulator (Gleeble 3500). The simulation process put into consideration the parameters of hot flat rolling at the pilot plant. The process was designed to present 7-consecutive passes. The 1st pass represents the roughing stage, while the rest 6- passes represent finish rolling stage. The whole process was executed at the temperature range 1100 to 900 ℃. The amount of strain starts with 23.5% at the roughing pass and decreases continuously to reach 7.5 % at the last finishing rolling pass. The flow curves of the alloy are abstracted from the stress-strain curves resulting from the simulation process. The flow curves reveal strain hardening from a pass to the other up to pass no. 7, as a result of decreasing the deformation temperature and increasing of cumulative strain. During pass no.6, the deformation process enhances the dynamic recrystallization phenomena to be dominant, where the Z-parameter would be high. Representative samples were taken and machined from Y-black cast to suite flat hot deformation. A thickness reduction from 36 mm to 8 mm was executed by hot forging to represent the roughing stage. Multi-consecutive passes were carried out to reduce the thickness from 8.0 mm to 3.0 mm representing the finishing hot rolling stage. Multi-pass cold rolling was carried out for a thickness reduction from 3.0 to 0.5 mm, an intermediate annealing cycle became essential to regain the ductility of the cold rolled sheets. After finishing the cold rolling process, a high temperature annealing cycle was done at 900 °C for 1 hour for creation grain coarsening. Tensile and bending test done to show the samples sustain tensile and bending loads without cracks that will be indication for the good formability of this sheets and can be used effectively at electrical applications. The microstructure investigation reveals mixed ferrite grain size that mostly coarse, while the final cold-rolled specimens contain mainly shear bands, the intermediate annealing affects positively on ductility by replacing the shear bands with elongated stress-free α-grains. Finally, the high temperature annealing results in ultra-coarse ferrite grains. selected specimens were subjected to a magnetic investigation. It is worthy noticed that the specimens reveal very narrow hysteresis loops in addition to low level of permanent magnetization and coercivity. Furthermore, thinning of sheets played a major role in enhancing the magnetic properties.