International Journal of Iron & Steel Society of Iran
Year:2006 | Volume:3 | Issue:2|Papers Count:6

A low carbon Al-killed Ti-added steel was produced in Mobarakeh Steel Complex in Iran. Mechanical properties and microstructural characterizations of steel in the as-cast, hot-rolled, cold-rolled and annealed conditions are presented. Dilatometery tests were carried out to measure the finishing and annealing temperatures of steel. It was found that the addition of small amounts of Ti increased the transformation temperatures. In addition, microalloying with titanium improved the ductility of the produced slabs and hot rolled steel sheet. However, low temperature annealing of Ti−added cold-rolled steel sheets led to a decrease in ductility. The results indicate that the full softening of the Ti-added cold-rolled steel is completed for an annealing time of 2hr at 800°C.

Heat transfer mechanisms and the solidification process are simulated for a continuous casting machine and the geometric shape of the liquid pool is predicted considering different conditions. A heat transfer and solidification model is described for the continuous casting of steel slabs. The model has been established on the basis of the technical conditions of the slab caster in the continuous casting unit of Mobarakeh Steel Company. This model involves a two-dimensional (2-D) transient energy equation. The governing equation was solved using the finitevolume procedure. The boundary conditions of the mold, water spray cooling, and air cooling regions have been defined. The mathematical model is able to predict the shell thickness, temperature distribution in the mold and shell, and the interfacial gap between shell and mold. The modeling results were verified by the measured slab surface temperatures and a reasonable agreement was achieved.

In this Study, vanadium recovery from the steelmaking converter slag was studied. Salt roasting-basic leaching is the process which was applied to separate and extract vanadium from steel making slag. Ground slag was roasted after mixing with determined quantities of sodium carbonate. The effect of time and temperature of roasting and sodium carbonate content were studied. The optimum temperature, time and sodium carbonate content in the roasting process were found to be 1000°C, 45 min and 10%, respectively.Temperature, time, leachant concentration and particle size were optimized for leaching process. It was determined that sodium carbonate is the major leaching agent in comparison with sodium hydroxide. The most suitable conditions for leaching process was found to be 80°C, 60 min, sodium carbonate to sodium hydroxide mass ratio of 40-50:10 and particle size between 100 and 120 mesh. More than 80% of vanadium was recovered under optimum conditions.

In the present work, deoxidation and refining of 316LVM steel (Low carbon Vacuum Melted) during the vacuum induction melting process was studied. This grade of stainless steel is one of the most important materials in medical applications. Vacuum deoxidation by carbon is the first stage of 316LVM stainless steel production process. In this stage, aluminum must be absent to avoid killing the C-O reaction. Deoxidation product in the VIM process is in gaseous state which is tapped by vacuum pump system. For this reason, vacuum deoxidation by carbon is the best method for refining 316LVM steel. Vacuum induction melting has no significant effects on reduction of sulfur and phosphorus. After deoxidation in vacuum by carbon, addition of Al+Ca/Si is the best way for reducing the oxygen and increasing the steel cleanness.

USD7 is one of the steel products of Isfahan Steel Company. It is cast in continuous casting moulds and rolled up to a rod of 5 mm diameter. Finally, it is wire drawn up to 3 mm and used as welding electrodes. This steel contains 0.05 to 0.09 wt. % carbon. The acceptable limit of the aluminium in this class of steel is less than 0.003 wt%. Therefore, it is categorized as rimmed steel During forming process, there are some defects such as tearing and laminating that stop the forming process.The aim of this research is to evaluate the factors causing the aforementioned defects. It was found that there were many porosities in the cast ingot. The area around these porosities was analyzed with EDS method, and inclusions with MnO and (Fe, Mn)O chemical composition were observed. It was found that they were external inclusions (slag inclusions caused by reoxidation and entrapment phenomena). Because of the presence of these inclusions, these porosities are not welded together during rolling process. Therefore, in the next steps of the forming process, these defects are revealed.

In this study, slag penetration into a magnesia refractory monolithic was investigated by the crucible test method. A synthetic calcium aluminate slag system has been used to study commercial magnesia mix refractory for 1, 2, 3, 4, 5 and 6 hours at 1450oC and 1600oC.It has been shown that the penetration rate is controlled by a diffusion mechanism at 1450oC In this case, capillaries are the main channels of initial slag penetration into the refractory. In the penetration process of the slag system, calcium silicate was formed on the surfaces of MgO grains at 1450oC and around them by reaction between grain boundary and mayenite, as a main phase of slag with a low melting point.Dissolution of the refractory components in the slag could be supported by the penetration process at 1600oC In this case, dissolution of the refractory components in the slag not only makes new open channels, but also changes the local slag composition, resulting in an increase in surface tension and viscosity of the slag.