Mixing phenomena in a RH process has been studied numerically by solving the Navier Stokes equations along with the species concentration equation in a cartesian coordinate system comprising the geometry of the ladle and the snorkel fitted to it. The solution of the species concentration equation has been utilized to compute the mixing time in the RH ladle under different flow conditions. The numerical procedure and solution algorithm has been first verified by comparing the numerically obtained tracer dispersion curve, with the actual plant measurement, which agrees fairly well with each other. Mixing time for the RH process has been computed for different downleg snorkel size, snorkel immersion depth (SID) and steel velocity within the downleg and a non-dimensional mixing time correlation has been developed for the RH ladle taking the above three pertinent input parameters into considerations. The correlated non-dimensional mixing time equation predicts fairly well the computed result as well as the actual mixing time being observed in the plant.

An experimental perspex model of the BOF vessel was made to the scale of 1 : 6 on which mixing time measurements were done by injecting potassium chloride (KCl) at a certain point and measuring the conductivity of the solution with time. It was found that the mixing time in the vessel attained a minimum when the bottom nozzles (eight in number) were kept at a pitch circle diameter (PCD) ratio of 0.4 with combined blowing (top blowing as well as bottom blowing) but the mixing time became a minimum at a PCD of 0.5 when only bottom blowing was done. In order to get a finer position of the bottom nozzles so that the mixing time could still be minimized, a mathematical model was used (because experiment could not be done with so close placement of the nozzles in one setup) to simulate the flow in the vessel with the help of the two equation k-e turbulence model along with a discrete phase model to simulate the air bubbles being injected in to the vessel. The mathematical model could predict the mixing time in the vessel to a very good degree of accuracy when compared with the experimental observations for the PCD of 0.5. From the mathematical model it was predicted that the mixing time in the vessel could still be lowered if the bottom nozzles were placed at a PCD of 0.56 instead of 0.5.

In the present day competitive market scenario, steel producers are striving for high speed continuous casting with stringent and consistent quality as well as reduced production cost. The ladle furnace (LF) is a key unit for achieving the above objectives during secondary steelmaking. Proper control of process parameters during LF processing of liquid steel is essential. The paper reports development of a model based advisory system, called ladle furnace on-line reckoner (LFOR), for the prediction and control of temperature and composition of steel in a LF. The thermal and chemistry models employed in the LFOR system are based on simplified physics, material and heat balance, and statistical analysis of plant data. The LFOR system is provided with graphical user interface (GUI) to display the predicted composition and temperature profile. The control advice displayed on the screen provides guidance for arcing and addition to achieve the target temperature and composition. The LFOR system has been commissioned at LF No. 2 of the LD2 and Slab Caster Shop of Tata Steel, Jamshedpur and is designed to meet the requirements of sequence casting as well as to optimise the energy input and cost of alloying additions. The performance of the LFOR system was analysed and validated with data taken over 100 heats and was noted to be satisfactory.

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The focus towards the design of light environment friendly fuel efficient vehicles has led to an increase in the demand for high strength steels. As it is true for any developing country, the extra challenge for Indian steel industries is to produce such high strength steels at minimum cost. The aim of the present work was to develop two high strength steel grades with minimum tensile strengths of 540 and 590 MPa, in combination with good ductility and stretch flangeability, through the thin slab casting and rolling route. The present paper describes the alloy and process design methodology used for achieving the target properties. Several mill trials were taken to test the proposed design, wherein the target microstructure and mechanical properties were successfully achieved.