The hydrides in industrial lime,alumina,magnesia,and calcium fluoride were investigated through differential thermal analysis and X-ray diffraction,and their mass losses during heating up were studied by thermogravimetric analysis method.The results indicate that the industrial alumina,lime,and magnesia,which have more moisture or hydride and mainly include γ-Al2O3,Ca(OH)2,and Mg(OH)2,lose more mass during thermogravimetric analysis process.However,the mass of premelted slag consisting of lime,fluorite,alumina,and magnesia has almost no change,which means no hydride in it.Some relationships for calculating the mass loss were established according to the results of thermogravimetric analysis.These results will be in favor of setting up the rational calcination criterion for slag used in electroslag remelting process.
The process of Electrical slag surfacing with liquid metal(ESS LM)is a complex physical and chemical process including electric field,magnetic field,flow field and temperature field,etc.As the complicated technology and high cost of manufacturing compound rolls,simulating the relationship between ESS LM process parameters and physical fields of ESS LM process is important.Through the numerical simulation of finite volume method to the process of ESS LM in the conditions of different roll core diameters,slag amount,pouring speed,pouring temperature and input power,temperature field and flow field in different conditions were obtained.When the diameter of core material,operation voltage,pouring rate,pouring temperature and slag height of conductive mold was 250mm,40V,8mm/min,1750K and 50mm respectively,the depth of molten metal was 30mm and fusion thickness of core material was 5mm which was consistent with the experiment results.According to the simulation results,operation with voltage of 42V,cladding speed of 10mm/min,pouring temperature of 1760K and slag height of 54mm in the conductive mould,achieved much more shallow metal pool,which is beneficial to vertical crystallization.
LI Wan-mingGENG XinLI Hua-bingYi Gao-songFENG HaoJIANG Zhou-hua
To investigate the hydrogen permeability of calcium fluoride used for electroslag remelting(ESR) process,"Gas-slag-metal" osmosis process under argon atmosphere saturated with water vapor at 318 K was used to study the hydrogen permeability of slag containing calcium fluoride.The results indicate that the conventional slag,consisting of 70% CaF2 and 30% Al2O3,has the lowest hydrogen permeability.A parameter EH was proposed for evaluation of the hydrogen permeability of slags containing calcium fluoride.The hydrogen permeability decreases with increasing EH to a certain extent.An appropriate choice of slag for the ESR process can be obtained.These results also suggest that the hydrogen pick-up in steel after remelting might be reduced when a slag with low hydrogen permeability is used.
