| With the development of the society,especially thick slab continuous casting billet manufacturing as large mechanical manufacturing industry,military industry,nuclear power and other pillar industries,in the field of play an important role.And also plays an important role in the field of casting compared to the slab continuous casting billet production with high efficiency,the economic advantages of the low cost,highly automated production process.Therefore,slab continuous casting billet quality products have become the focus in the metallurgical workers.By continuous casting billet production general principle,the thick slab continuous casting billet in continuous casting machine from liquid steel to the process of solidification is the key to improve the quality of its internal links.Mainly by throwing rate flow capacity,mold and secondary cooling zone of the change of the key process parameters by influencing the characteristics of the cooling speed of slab continuous casting billet of indirect control of its product and finished product quality.Through the above description,the cooling speed(can be indirectly as solidification speed)is to determine plate of continuous casting slab quality directly influence factors.Because the same slab continuous casting billet for different parts of the correspondence of the fast cooling rate,the head can be considered under the condition of transient cooling solidification,and the waist and the tail can be considered under the condition of steady-state cooling solidification,which for the study of solidification rate on the plate continuous casting slab structure and the influence of element distribution,and so on and so forth provides operability.This study through the thick slab continuous casting billet in the head,and the tail different elements distribution on cross section and the macro and micro structure of the experimental test results found that: over thick plate at different location of the continuous casting billet of element distribution on cross section,cooling speed is the main reason,influence its distribution in the cross section of edge position due to the large cooling rate,lead to solute atoms constantly to the forefront of the liquid-solid interface diffusion,element content is low.And at the center of the cross section,due to the temperature gradient is small,results in relatively homogeneous distribution of elements.Can also be found at the same time,because of the continuous casting billet in the process of solidification on the phenomenon of "small ingot cause longitudinal element diffusion effect is not obvious,thus casting billet and the tail element content in the head,there is not much difference;For plate continuous casting billet in the head,and the tail on the cross section in terms of macroscopic structure,cooling speedis a key factor to determine the forming regularity of same.Different location of the continuous casting billet in cross section on the macro structure similar,respectively: edge of chilling solidified fine grain area,the outer area of the columnar crystal and center position of the shaft rough grain area,at the same time can also be found in the center of a cross section axis loose defects,showed the mould inside the head to the bottom of the feeding effect needs to be improved;Compared with the cooling rate of continuous casting billet macrostructure and the effect of cooling rate and carbon content to the formation of continuous casting billet microstructure.By the thick slab continuous casting billet in the head,and the tail cross-sectional microstructure observation result shows: different location due to the object of this study was to carbon content 0.4%(mass fraction)of hypoeutectoid steel slab continuous casting billet,therefore the microstructure consists of ferrite and pearlite,with declining cooling rate and carbon content,and ferrite grain tend to form the polygon shape and volume fraction of the drops,and pearlite lamella of spacing of larger and higher volume fraction. |
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