SynopsisA V-shaped segregation, found in a sulfur print of longitudinal strand section, has been macroscopically investigated. A simple model, using polyethylene particles of 2 mm diameter, has been prepared to simulate formation of the V-shaped segregation.The results obtained are summarized as follows :(1) The V-shaped segregation is observed only in an equiaxed crystal zone very periodically along the casting direction.(2) The frequency of the V-shaped segregation becomes smaller, while its density becomes larger with increase in the thickness of the equiaxed zone.(3) The mechanism of formation of the V-shaped segregation may be explained as follows; The enriched liquid between the equiaxed crystals is sucked and flows downwards and is accumulated along the planes which are made by the forcible movement of the equiaxed crystals piling in the end of the solidification regions toward the strand center.(4) The periodicity of the V-shaped segregation is quantitatively explained by the rheological approach assuming the equiaxed crystals piling in the end of the solidification regions as cohesive particles.
The mechanical pro/Jerties of steel are largely affected by the existing non-metallic inclusions. Though several sources of the oxide inclusion are already known , there are only afew investigations in which the e.!Ject of secondary oxidation are clarified. The eifects of the casting in a non-oxidizing atmosphere on the qualify of continuously cast stainless slab and that of conventionalfy teemed steel ingot are reported in this /Japer. Experimental results indicate that both th.e amounts of macroscopic inclusions and the absorbed nitrogen and hydrogen are markedly decreased by the applica tion of this method. Consequentiv, the defects qf the /J1w/ucls observed by th.e ultra-sonic test, cracks due to the /Jreci/Jitation of A IN, }ish eyes and so on, are decreased considerably. From this /Joint of view, almost all the killed steel are now cast ill all inert aI'gon gas atmosphere, and the qualifY of the products is highry improved.
Synopsis:A study has been made of the effect of pouring conditions on large inclusions in bottom part of ingot,the following results have been obtained. 1)The pouring tempereture has the strongest effect on the amount of large inclusion.The temperature becomes lower,the amount of large inclusions increases.2)The rimming time is an important factor next to the pouring temperature.When the rimming time is short,a large amounts of relatively small size inclusions retain, even if the pouring temperature is sufficiently high.3)The effect of ingot dimension on large inclusions can not be recognized.Ingot dimension is a negligible factor compared with two factors mentioned above in the ordinary pouring conditions. 4)Factors influencing the composition of large inclusions were confirmed.The relation,however, between the composition and the amount of large inclusions could not be observed.
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