Fundamental Research On Pouring Large Metal Ingots From Metal Droplets Passing Through The Refining Slag Layer

Large steel ingots are widely used in the basic components and facilities of heavy equipment such as metallurgy,transportation,electric power and ships.Their manufacturing capacity is one of the important indicators to measure the modern industrial level of a country.Large steel ingots are generally populated,while high clean large ingots are usually vacuum cast.In order to further improve the cleanliness of large steel ingots,the research group proposed a new process of vacuum casting high-cleaning large steel ingots through metal droplets through the refining slag layer.The new process can further dehydrogenate,desulfurize and go in the vacuum casting process.Based on the dehydrogenation behavior and refinement kinetics model of the new process,it is of great theoretical and practical significance to carry out thermal experimental research on the behavior of steel droplets passing through the slag layer and the desulfurization and control of inclusion behavior during the traversing process..In this paper,GCr15 bearing steel is used as experimental material,and the typical CaO-SiO2-Al2O3-MgO quaternary slag system is selected.The thermal behavior of steel droplets passing through the refining slag layer is studied by laboratory thermal experiments.The droplet diameter and slag are analyzed.The influence of process parameters such as layer thickness and slag composition on the penetration of steel droplets through the slag layer.Through the metallographic microscope,oxygen and nitrogen content detection,sulfur content detection,slag viscosity measurement and SEM scanning electron microscope and other detection methods,the desulfurization and de-intercalation behaviors of steel droplets passing through the slag layer were investigated.Mainly got the following conclusions:(1)When R=5.5,w(Al2O3)=30%,w(MgO)=5%,h=15mm,the steel droplets can completely pass through the refining slag when the droplet diameter D=4/6/8/10mm Layer;when D=6mm,the steel droplets can completely pass through the refining slag layer with h=5/10/15mm;D=6mm,h=15mm,w(Al2O3)=30%,w(MgO)=5%WhenR=3/5.5/6.5/8,the steel droplets can completely pass through the refining slag layer;when R=5.5,w(MgO)=5%,w(Al2O3)=15%/20%,the steel droplets cannot be completely through the refining slag layer,when w(Al2O3)=25%/30%,the steel droplets can completely pass through the refining slag layer;R=5.5,w(Al2O3)=30%,w(MgO)=5%/15%The steel droplets can completely pass through the refining slag layer.(2)The slag viscosity and droplet diameter are important factors influencing the ability of steel droplets to pass through the slag layer.When the viscosity of the slag is 0.15 Pa-s,the condition that the steel droplets can pass through the refining slag layer is:D>2.1 mm;when the droplet diameter is 6 mm,the condition that the steel droplets can pass through the refining slag layer is:?<2.13Pa·s.(3)When R=5.5,w(Al2O3)=30%,w(MgO)=5%,h=15mm,the steel droplets have good desulfurization and de-intercalation effects after passing through the slag layer,and the desulfurization rate generally follows the particle size.The smaller the steel droplet size,the better the effect of de-doping;the MnS inclusions in the steel are reduced,the main inclusionsare magnesium-aluminum spinel and SiO2,MgO oxide inclusions;(4)When R=5.5,w(Al2O3)=30%,w(MgO)=5%,D=6mm,the desulfurization rateincreases with the increase of the thickness of the slag layer;when the thickness of the slag layer is small,the desulfurization effect is not obvious,steel The number of inclusions increases,and the composition of inclusions is more complicated;(5)With the increase of alkalinity,the desulfurization rate first increases and then stabilizes;with the increase of alkalinity,the total amount of inclusions in steel increases,and the inclusions in steel are mainly inclusions of spinel and SiO2 oxide;When w(Al2O3)<30%,w(MgO)>5%,the slag layer desulfurization effect is not good,and the number of inclusions in the steel increases.In the experimental range designed in this paper,the slag composition with good desulfurization and de-intercalation effects is:R:5.5?6.5,w(Al2O3)=30%,w(MgO)=5%.