Mathematical Simulation of Flow Phenomena in CAS-OB Refining Ladle

The deoxidation behaviors of alloys bearing barium in pipe steel were researched with MgO crucible under argon atmosphere in MoSi 2 furnace at 1 873 K. The total oxygen contents of molten steel, the distribution, size and morphology of deoxidation products in the steel were surveyed. The metamorphic mechanism for deoxidation products of alloy bearing barium was also discussed. The results show that applying alloy bearing barium to the pipe steel, very low total oxygen contents can be obtained, and deoxidation products, which easily float up from molten steel, can be changed into globular shape and uniformly distributed in steel. The equilibrium time of total oxygen is about 25 min, and the terminal total oxygen contents range from 0 002 0 % to 0 002 2 % after treating with SiCa wire. The best deoxidizers are SiAlBaCa and SiAlBaCaSr.

Vacuum Treatment for Simultaneous Desulphurization and Dephosphorization of Hot Metal and Molten Steel

The vacuum treatment for simultaneous desulphurization and dephosphorization of hot metal and molten steel with pre-melted CaO-based slag was carried out.For pre-treatment of hot metal,both desulphurization and dephosphorization are improved with the increase of CaO in slag,but deteriorated with the increase of CaF2 in slag.The average desulphurization and dephosphorization rate is 68.83 % and 78.46 %,respectively.For molten steel,the substitution of BaO for CaO in slag has minor effect on simultaneous desulphurization and dephosphorization.The desulphurization and dephosphorization rate is higher than 90% and 50% respectively with the lowest final sulfur and phosphorus mass percent being 0.001 2% and 0.010%,respectively.The overall effect of simultaneous desulphurization and dephosphorization of molten steel is better than that of hot metal.

Effect of Top Slag Basicity on Quality of Steel Treated by Exothermic Agent SiFe and SiCaBa during Chemical Heating

The effect of top slag basicity on quality of steel treated with SiFe and SiCaBa alloy as exothermic agent in chemical heating was studied.These experiments were carried out in MoSi_2 laboratory furnace with 0.2 kg molten steel for equilibrium test and 2 kg molten steel for simulation test respectively.These results showed that the adjusting basicity of top slag with CaO is effective to prevent rephosphorization and resulphurization,and it is possible to dephosphorize and desulphurize and remove the inclusions from molten steel when basicity R of the top slag is adjusted to 2.0 — 3.10,and SiCaBa alloy is better than SiFe alloy in this relation.

Relationship between Thermodynamic Parameters for Mn-Fe Melt and Temperature

The carbon solubility in Mn-Fe melts were measured at 1350℃,1375℃,1425℃and 1450 ℃,and accordingly the calculated equations were obtained.By thermodynamic derivation and calculation,some relationships between thermodynamic parameters for Mn-Fe melt and temperature were obtained.

Study on Oxygen Potential of Ferromanganese Melt during Desiliconization

The first micro segregation under conditions of twin roll strip casting was simulated. The relationship between the temperature and solid fraction in the mushy zone was given. The temperatures such as ZDT, LIT were got from this simulation. Then using the turbulent model, the flow field and thermal field in the pool of twin roll strip caster was simulated. The speed and temperature at different casting speed was given, and the results were also explained. By these two simulations, the appropriate casting speed can be found. These simulations can provide effective data for controlling the twin roll strip casting process.

Thermodynamic Model for Calculating Activity of Nitrogen and Boron in Fe-C-B-N Molten Metal

The solubility of nitrogen in Fe-C-B-N system was measured at 1 758 K,and the computational model on activity （action concentration） of nitrogen and boron was established based on phase diagram and the coexistence theory about metal melt structure model. Comparing the computed results with the experimental results,satisfactory conclusion can be obtained. The result shows that BN and B4C can exist in Fe-C-B-N molten metal at high temperature,which consequently restrains the nitrogen removal from the melt. However,B4C content is extremely low. Before graphite is precipitated,the influence of carbon on activity of nitrogen in melt is higher in ternary system than in binary system; however,this effect is contrary to that after graphite is precipitated.

Model of Calculating Activity of Nitrogen and Vanadium in Fe-C-V-N Molten Metal

The solubility of nitrogen in the Fe-C-V-N system was measured at 1 708 K and the model of calculating activity （action concentration） of nitrogen （N） and vanadium （V） was derived according to the phase diagram and the coexistence theory of the metal melt structure. The solubility expression of nitrogen in the Fe-C-V-N system at 1 708 K was ωN =0. 058 194-0. 010 367ωc＋0. 005 543 4ωv. Comparing the computing results with the experimental resuits, a satisfactory conclusion could be obtained. The analysis of the Fe-C-V-N system using this model showed that VN was present in a high temperature metal melt, which would reduce the action concentration of nitrogen obviously. It was consequently disadvantageous to the removal of nitrogen from hot metal.