Papers by Keyword: Billet

Abstract: Numerical simulations of a billet heating furnace with direct flame impingement operating in a metallurgical plant were carried out and the results compared to measurements obtained in an industrial environment. The transport equations for mass, momentum, energy and mass of chemical species in reactive flow were computed with the use of ANSYS FLUENT. Turbulence, combustion and radiation were modeled using, respectively, the realizable k-ε model, the finite-rate/eddy-dissipation model and the finite volume scheme. The model was used to simulate the furnace operating under the conditions that occurred during an energy audit carried out at an industrial facility (413 kW firing rate and 80% excess air). The predicted furnace efficiency, 72.5%, is in very good agreement with the one obtained in the energy audit (0.4% difference). The flue gas temperature at the end of the second preheating zone was measured during the energy audit and its value compared to the one predicted. In this case, the agreement between measurements and simulation is not so satisfactory (23% difference). This paper presents the validation of a CFD model of a direct-flame impingement furnace for billet heating in a full-scale industrial situation, which was not previously published, and opens the way for more simulations and detailed studies of the phenomena that occur inside this type of furnace.

Abstract: Non-metallic impurities in continuous cast billets are evaluated by a growth rate of edge point impurities. The first part of our research was devoted to a relationship between the growth rate of edge point impurities and other macrostructure defects. A correlation-regression analysis of steel macrostructure quality showed the relationship between the rate of edge point impurities and segregation cracks in general, as well as corner streaks. The second part of our research indicated that impurities in billets from conventional carbon steel were crucially influenced by a method of pouring steel from a tundish into a mould. By transferring from open stream casting to shrouded casting, the quantity of non-metallic impurities in billets decreases by 7 times. In case of open stream casting, prevailing inclusions are oxides resulting from secondary oxidation, while the growth rate of edge point impurities in billets increases with an increased content of sulphur and phosphorus in steel, and decreases with an increased manganese/sulphur ratio. In case of shrouded casting, non-metallic impurities are limited to casting temperature and speed: steel overheating in the tundish above the liquidus temperature and withdrawal speed of billets. Less non-metallic impurities in case of the shrouded casting are contributed by steel overheating in the tundish above the liquidus temperature over 30oС and withdrawal speed, not exceeding 2.5 m/min.

Abstract: The influence of the electromagnetic mixing (EMM) of liquid metal in the mold of the continuous casting machine on its thermal work, the formation of the structure and properties of cast billets are investigated. The influence of the current and frequency of EMM on the mechanical properties, macro-and microstructure of round and square sorted billets was established.

Abstract: The influence of the St.3sp, 40 and 85 steel grades chemical composition, temperature of the metal in the tundish ladle, billet cross-sectional dimensions (150 × 150 and 152 × 170 mm), the sulfur content in the metal on the speed of withdrawal of the billets from the CCM mold has been investigated. It was established, that the change of the metal temperature in the tundish ladle of the CCM has the greatest effect on the billet withdrawal speed, the change of carbon content in the steel and the billet cross-sectional dimensions influence in less extend, and the sulfur content in the cast steel does not affect at all.

Abstract: M2 steels, the typical Co-free high speed steel (HSS) possessing hardness level of 63~65 HRc, are most widely used for cutting tools. On the other hand, Co-containing HSS’s, such as M35 and M42, show a higher hardness level of 65~67 HRc and used for high quality cutting tools. In the fabrication of HSS’s, it is very important to control cleanliness and eutectic carbide structure of the ingot and it is required to increase productivity at the same time. Production of HSS ingots includes a variety of processes such as casting, electro-slag remelting (ESR), forging, blooming, and wire rod rolling processes. In the present study, electro-slag rapid remelting (ESRR) process, an advanced ESR process combined by continuous casting, was successfully employed to fabricate HSS billets of M2, M35, and M42 steels. Distribution and structure of eutectic carbides of the billets were analysed and cleanliness, hardness, and composition profile of the billets were also evaluated.

Abstract: The main objective of this paper is to study the effect of extrusion parameters (extrusion stresses and temperature) and die geometry, i.e. extrusion radius, on the extruded aluminum quality using FEM Simulation Technique. For this purpose, the general FEA Software ABAQUS was used to set up the finite element model of the warm aluminum extrusion in two dimensions (2D). Aluminum alloy Al-2014 was used as billet material, with 40mm diameter and 75mm length. The extrusion process was modeled as isothermal, which means that the billet material was preheated at a specific temperature and then pressured into the circular die, with extrusion ratio 3.3. Optimized algorithms for extrusion parameters were proposed regarding the concluded simulating results. The results showed that small die angles required higher extrusion load than large die angles. In all die geometry used, the deformation of aluminum billet, which is caused by shearing and compression stresses, happened in a small sectional area (bearing area). The results also showed that, the values of these stresses can increase or decrease depending on the die entrance angle and the die bearing length. To avoid the effects of these stresses on die dimensions; the hardness, material selection, and geometry should be well calculated. An axis-symmetrical 2D geometric model of the tooling and billet was constructed for the analysis. Data obtained from the FE model included die-work piece contact pressure, effective stress and strain and material deformation velocity. The correlation between the calculated and FEA data was obtained in this research.

Abstract: In this paper, a solution for the automatic control of the driving mechanisms that load/unload billets in/from a rotary hearth furnace is proposed. This problem is approached because in the actual stage the control of the loading/unloading machines is made manually. The treated solution is based on using, for each machine, a direct-current motor (d.c. motor) supplied through a direct-current converter (d.c. converter) for the forward-backward moving of the two machines to/from the furnace. In this context, the tuning of the controller implemented in the converter is made in order to assure the imposed speed of the motors and implicitly of the machines, respectively an appropriate speed evolution of the motors in the period of their acceleration and deceleration to assure the machines correct positioning.

Abstract: Continuous casting process parameters such as casting speed, superheat, secondary cooling water flow rate have greatly affections to central defects in SWRH82B billet. These parameters were investigated by the methods of chemical content analysis and etch test for macrostructure in some steel plant of china. The results shows that the central defect of SWRH82B billet can be improved when the superheat is controlled at the range of 15~25°C, casting speed is 1.80m•min-1 and secondary cooling water flow rate is 0.72 L•kg-1.

Abstract: There is a new idea on the billet casting Q235 with size of 165mm×165 mm,It involves a couple technology to cool molten steel both from inside and outside, namely: to emplace an inner cooler -a pipe with the shape of letter U in the mould. It aims to increase the thermal conductivity and improve the inner structure of the billet. With the help of Fluent -a kind of CFD business soft ware, a numerical simulation is undertaken to testify the condition of the molten steel in the inner-outer cooling mould coupled by flow field and temperature field.

Abstract: In this study, the temperature field distribution of 22CrMoH billet is first obtained by simulating continuous casting process using moving boundary method. On the basis of the above data, the microstructure of 22CrMoH gear steels billet was simulated based on CAFÉ (Cellular Automaton – Finite Element Analysis) method, together with the effects of alloying elements such as Cr, Mo, Si, Mn on the microstructure of this billet. The simulated result agrees reasonably well with that of the actual product. And it suggested that under the reasonable extend of current steel grade, the increased amount of Si and Mn can steadily widen the proportion of equiaxed grains, lead to the increase in equiaxed grain amount, hence the decrease in equiaxed grain average radius; The increase in Mo content is able to enhance the nucleation amount; Proper decrease in Cr content favors the increase in proportion of equiaxed grains, but little effects on grain’s amount and radius. Further, the composition of alloy elements under the specified scope of 22CrMoH grade was optimized and the simulated results showed that the microstructure has vastly improved, as the proportion of equiaxed grain rose nearly doubled, the grains amount has increased by 19.96%, and average radius has decreased by 9.20%.