Fe-4.5wt%Si strips were produced using a vertical type twin-roll strip casting process. The effect of superheat on the microstructure and texture was studied through thickness direction of the as-cast strips. The heterogeneity of texture and microstructure through thickness direction of the strips was observed. In the case of superheat 20°C, Goss texture evolved between the subsurface and the middle layer and major rolling texture with minor solidification texture evolved in the center layer. In the case of superheat 30°C, solidification texture of {100}͗uvw͘ fiber evolved from the surface to the center layer.

A three-dimensional model has been formulated to calculate the shape of the general preform, using vector calculus. The shape of a rod, tube, plate, or irregular preform can be calculated at given spray forming conditions. The shape of a spray-formed rod was analyzed at various spray forming conditions using the three-dimensional model. The effects of spray forming parameters, such as spray distribution parameters, angular velocity of rotation, withdrawal velocity, spray angle, and eccentric distance on rod shape, were analyzed. The most important parameters affecting the shape of rods are the spray distribution parameters and the withdrawal velocity. The dynamic evolution of rod shape with a stepwise variation of the withdrawal velocity during spray forming was investigated. The effect of a stepwise change of the withdrawal velocity was the same as that of the scanning atomizer. The calculated surface profiles were compared with those of spray-formed 7075 aluminum alloy rods prepared on a pilot scale. The calculated results for the surface profiles were in agreement with those of the spray-formed rods.

Fe-4.5wt%Si strips were made using vertical type twin-roll strip casting process, and the microstructure and texture of as-cast strips were studied through thickness direction. The heterogeneity of the texture and microstructure through thickness direction was observed. Between the subsurface layer and the middle layer, Goss texture, with the subgrains of low angle grain boundary was evolved by the shear deformation. In the center layer, major rolling and recrystallization textures with minor solidification texture were evolved.The deformation behavior during strip casting process was simulated by hot rolling of Al alloy with temperature gradient through thickness direction. And the shear and normal strains distribution through thickness direction were measured. The heterogeneity of the texture and the microstructure through thickness direction resulted from the strength gradient, which originated from the temperature gradient through thickness direction.KEY WORDS: Fe-4.5wt%Si; Twin Roll Strip Casting; deformation behavior; texture; hot rolling strength gradient; temperature gradient..given in Table 1. The schematic diagram of the twin-roll strip caster is shown in Fig. 1. Hole-type nozzle was positioned at the center of the tundish. Molten metal was supplied from an induction furnace to the tundish by using a temperature-controlled ladle. Specimens for metallographic examination were etched with Nital (2 vol% Nitric acidϩ98 vol% ethanol) reagent. The microstructure of the specimens was observed at the transverse direction by using optical microscope and EPMA. At the normal direction, subgrain boundaries in the subsurface layer were investigated by using transmission electron microscope. Texture MeasurementThe texture variation of the as-cast strip was investigated through thickness direction. The position through thickness direction can be used by a parameter s, defined as sϭ2a/d, where a and d are the distance from the center layer of strip and the thickness of the strip, respectively. The parameter s is called the normalized thickness. To analyze quantitatively the texture of the strip, three incomplete pole figures, {110}, {200}, {211}, were measured in the range of the polar angle a from 0°to 70°with Co Ka 1 radiation in the Seifert D3000 with PTS goniometer. Samples for pole figures measurement were etched at room temperature in a solution of 90 ml H 2 O 2 and 10 ml HF for the stress relieving from the mechanical polishing. ODF was calculated from the measured pole figures by WIMV method.10) The orientation of the subgrain in subsurface layer was investigated by the EBSD, which was operated by Link Opal system at JEOL 6300 SEM. Temperature Gradient Hot Rolling Simulationduring Strip Casting Process The deformation behavior during strip casting was simulated by hot rolling of Al alloy with temperature gradient through thickness direction, called the temperature gradient hot rolling simulation. Figure 2 shows a schematic diagram of the temperature gradient hot rolling simulation. The curved plate of Al-0.1wt...