| This text makes Contrast Detection of doing Contrast Detection about organizations of the SPHC billet, distributions, sizes and shape of occluded foreign substance in the situation that whether electromagnetic braking is put in in the Continuous casting process by making use of metalloscope, polarizing microscope, Super depth of field of 3D electron microscope, scanning electron microscope, energy spectrum and so on. Studying the influence to slag inclusion, organization, mechanical property of EMBR and the result indicates that there are circle, triangle, and square kinds of slag inclusions and different shapes of occluded foreign substance are supposed to be classified to different elements of occluded foreign substance, of which the circle ones are the most and square ones follows, the least are the triangle ones.No matter what shapes the occluded foreign substances are, without any electromagnetic braking, the amount of the occluded foreign substances keep average and in the heart part the amount is the most. After using EMBR, in the edge dirction of slab width, the amount of occluded foreign substance adds up quickly, making the amount in the other parts reduces and keeps average. So the occluded foreign substances get together to the edge and the number of slag inclusions on the edge is 2 mulriples of the one in the centre 2.08 mulriples of the one from the 1 quarter to the up. Slab width to the edge in Slab width direction. In Slab width direction, the number of slag inclusions is almost the same with position modification and without electromagnetic brake. But the number is reduced in a quarter up to the thickness of the slab. It is analyzed in the total number of slag inclusion that the number of casting blank is reduced little after electromagnetic braking. In the function of EMBR, the bigger occluded foreign substances move to the edge to be together so that it is easy to sort out them. the size Of slag inclusions belonging to the micro- occluded foreign substances are smaller than 20μm no matter whether electromagnetic braking is used. the slag inclusions are Al2O3, Magnesium aluminate class, silicon carbide and so on. There are on influence to the morphology and Composition no matter whether electromagnetic braking is used. The EMBR matters little to the ingredient and shape of occluded foreign substances. The affect on distribution from EMBR to slag inclusion depends on magnetic field which makes affect on hot metal flow to get indirect effect. In the action of a magnetic field, heat distribution is changed on the edge of casting blank to make the heat loss get down so that the amount of isometric crystal adds on the edge. the casting blank which uses electromagnetic braking is because heat dissipation is fast and the cooling is huge on the edge, which makes the amount of super-cooled austenite adds to transform to more and more pearlites. After EMBR is used, The strength of the Crystallizer narrow side by liquid steel flowing in order to improve the temperature of liquid steel under meniscus and slow down the speed of casting blank cooling, which makes the amount of pearlite down to keep the distribution on the fracture surface of the whole casting blank in average. The crystalline grain of organizations after rolling is detailed after EMBR. The organization after rolling is refining to improve the yield strength and be helpful to improve plasticity but it is unclear that whether it can reduce work hardening!... |
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