A mathematical model, including electromagnetic field equation, fluid flow equation, and temperature field equation, was established for the simulation of the electroslag remelting process. The distribution of tempera...A mathematical model, including electromagnetic field equation, fluid flow equation, and temperature field equation, was established for the simulation of the electroslag remelting process. The distribution of temperature field was obtained by solving this model. The relationship between the local solidification time and the interdendritic spacing during the ingot solidification process was established, which has been regarded as a criterion for the evaluation of the quality of crystallization. For a crucible of 950 mm in diameter, the local solidification time is more than 1 h at the center of the ingot with the longest interdendritic spacing, whereas it is the shortest at the edge of the ingot according to the calculated results. The model can be used to understand the ESR process and to predict the ingot quality.展开更多
Experiment was carried out after the process parameters were calculated by the model previously established. The relationship between interdendritic spacing and local solidification time （LST） mainly determined by p...Experiment was carried out after the process parameters were calculated by the model previously established. The relationship between interdendritic spacing and local solidification time （LST） mainly determined by process parameters was exposed. Furthermore, the extent of segregation was studied. The results indicate that LST and interdendritic spacing are the largest and the amount of Laves phase as a result of the niobium segregation is the highest in the center of the ingot, whereas the opposite results are obtained at the edge of ingot. The extent of element segregation and the amount of Laves phase can be reduced when appropriate parameters are used. Therefore, the duration of subsequent homogenization treatments for 718 is shortened and the alloy quality is improved.展开更多
The pick-up of hydrogen during electroslag remelting process for several slags consisting of CaF2-Al2O3-CaO-SiO2-MgO had been investigated.The laboratory-scale remelting experiments had been carried out in open air an...The pick-up of hydrogen during electroslag remelting process for several slags consisting of CaF2-Al2O3-CaO-SiO2-MgO had been investigated.The laboratory-scale remelting experiments had been carried out in open air and water-free argon atmosphere,and then the influencing factors were analyzed.It had been found that the hydrogen content in steel varied with different slag compositions.The compositions and state of slag had significant effect on the hydrogen level in steel.Partial return slag and premelted slag could avoid the hydrogen pick-up especially in the early stages of the process.However,premelted slag was the optimum state to control the hydrogen pick-up in steel.Experimental results indicated that water-free argon atmosphere was very favorable to the control of hydrogen in steel in the normal remelting period.展开更多
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 thermogravime...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.展开更多
基金Project(52174303)supported by the National Natural Science Foundation of ChinaProject(2125026)supported by the Fundamental Research Funds for the Central Universities,China。
基金Item Sponsored by Weaponry Pre-Research Fund (51412020304QT0901)
文摘A mathematical model, including electromagnetic field equation, fluid flow equation, and temperature field equation, was established for the simulation of the electroslag remelting process. The distribution of temperature field was obtained by solving this model. The relationship between the local solidification time and the interdendritic spacing during the ingot solidification process was established, which has been regarded as a criterion for the evaluation of the quality of crystallization. For a crucible of 950 mm in diameter, the local solidification time is more than 1 h at the center of the ingot with the longest interdendritic spacing, whereas it is the shortest at the edge of the ingot according to the calculated results. The model can be used to understand the ESR process and to predict the ingot quality.
基金Item Sponsored by Weaponry Pre-Research Fund (51412020304QT0901)
文摘Experiment was carried out after the process parameters were calculated by the model previously established. The relationship between interdendritic spacing and local solidification time （LST） mainly determined by process parameters was exposed. Furthermore, the extent of segregation was studied. The results indicate that LST and interdendritic spacing are the largest and the amount of Laves phase as a result of the niobium segregation is the highest in the center of the ingot, whereas the opposite results are obtained at the edge of ingot. The extent of element segregation and the amount of Laves phase can be reduced when appropriate parameters are used. Therefore, the duration of subsequent homogenization treatments for 718 is shortened and the alloy quality is improved.
文摘The pick-up of hydrogen during electroslag remelting process for several slags consisting of CaF2-Al2O3-CaO-SiO2-MgO had been investigated.The laboratory-scale remelting experiments had been carried out in open air and water-free argon atmosphere,and then the influencing factors were analyzed.It had been found that the hydrogen content in steel varied with different slag compositions.The compositions and state of slag had significant effect on the hydrogen level in steel.Partial return slag and premelted slag could avoid the hydrogen pick-up especially in the early stages of the process.However,premelted slag was the optimum state to control the hydrogen pick-up in steel.Experimental results indicated that water-free argon atmosphere was very favorable to the control of hydrogen in steel in the normal remelting period.
基金Item Sponsored by National Natural Science Foundation of China(50904015)Postdoctoral Science Foundation of China(20090450020)Fundamental Research Funds for Central Universities of China(N090402012)
文摘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.
