669. 187.56

екзотермічний електропровідний флюс
електрошлаковий переплав
шлакова ванна
гранулометричний склад
продуктивність процесу
якість металу
electrically conductive exothermic flux
electroslag remelting
slag bath
granulometrіc composition
process productivity
metal quality

Експериментальними методами встановлено, що розроблений спосіб твердого старту з використанням екзотермічних флюсів, що проводять електричний струм у твердому стані, істотно знижує час наведення шлакової ванни необхідного обсягу, підвищуючи продуктивність процесу. Запропонований спосіб старту електрошлакового процесу із використанням екзотермічних електропровідних флюсів не здійснює негативного впливу на якість донної частини злитка. Розроблені технологічні процеси прискореного наведення шлакової ванни на твердому старті як за монофілярною, так і біфілярною, або трифазною схемою ведення процесу. Властивості литої електрошлакової сталі 5ХНМ задовольняють вимоги, які пред’являються до механічних властивостей кованого металу відкритої виплавки. Гранулометричний склад екзотермічного флюсу в основному впливає тільки на процес наведення шлакової ванни витратним електродом.
The authors established that an effective way to improve performance of such electroslag processes as casting and remelting was the use of exothermic fluxes containing such components as: slag, ferro alloys and aluminum powder in quantities sufficient for exothermic reactions. In particular, the experimental techniques revealed that the presence of electrically conductive layer of exothermic flux allowed for electroslag process being carried out according to the monofilar, as well as bifilar or three-phase schemes at «solid» start. The conducted research testified that the use of exothermic alloyed flux does not result in lower quality of the metal on the bottom of an ingot. The macro-structural analysis revealed that the cast metal of the ingot-bottom was dense; cracks, cavities and other defects did not occur, and columnar crystals were directed almost in parallel to the center line of a templet; in the middle and upper parts a zone of columnar crystals is clearly revealed; in the central part there was a zone of equiaxed crystals; besides the content of sulfur in the bottom of the ingot under the proposed method of start was smaller than that in its middle and upper part. The micro- structural study of pollution of the stamping dice metal by nonmetallic inclusions demonstrated that the metal had low content of non-metallic inclusions, while the pollution of wrought metal was significantly higher than the pollution of electroslag cast metal. The authors proved that the properties of electroslag cast steel 5HNM met the requirements for mechanical properties of openly melted wrought metal. The component of exothermic flux was found to be worthy being used, which is a waste of rolling or forging and pressing industry with particle size of 0.1 ... 2.5 mm and alloying elements with particle size of 0.1 ... 6.0 mm. It has been determined experimentally that granulometric composition of exothermic flux mainly affected only the process of restoring the slag bath in the application of consumable electrode. As a result of comparative tests of the effective option of the developed method of start and the applied methods of solid and liquid starts of the electroslag remelting, the parameters were obtained, which testify that the developed method of start of electroslag remelting can improve the performance of electroslag remelting process and increase the production of useful metal by 2...7 %. In addition, the authors found that the melting of exothermic flux the component of slug is formed: aluminum oxide (Al2O3), the mass of which can contain up to 20% of the required mass of the working flux being melted.