A three dimensional numerical model of the heat exchange during a charge heating process in a pusher furnace, using the finite element method, was used in this study. The radiative heat exchange in the furnace chamber was carried out based on two methods: the zone method and the method of basing on the average configuration ratio. In the zone method the flux of radiation energy reaching the surface of the heated charge was determined by performing calculations of brightness in a multi-surface closed system which is the pusher furnace chamber filled with an emitting-absorbing medium. In the second case an average configuration ratio was used by setting the radiation energy flux through linking the walls temperature with the furnace atmosphere temperature.
A. Gołdasz, Z. Malinowski, T. Telejko, M. Rywotycki and A. Szajding
B. Hadała, A. Cebo-Rudnicka, Z. Malinowski and A. Gołdasz
The Influence of Thermal Stresses and Strand Bending on Surface Defects Formation in Continuously Cast Strands
Improvement of slab surface quality is a very important goal in continues casting process of steel. It is closely coupled with casting line productivity and tendency to increase casting speed. In such a case rapid cooling of strand surface mast be employed. It results in thermal stresses development and formation of surface cracks if casting speed, cooling conditions or the arc of casting machine are not appropriate. The strain and stress fields in continuously cast strand have been determined based on the developed thermo-mechanical model and finite element software. It allowed to calculate variation of selected criterions integrals over the hole casting line starting from solidification process in the mould and ending at cutting section. Steady solution to heat transfer equation has been used to calculate strand temperature field. Mould temperature has been calculated from the three dimensional transient model. Finite element method has been employed to build steady and transient heat transfer models. Finite element solution accuracy to the temperature field has been improved. New algorithm of the solidification heat handling has been developed to stabilize a steady solution to the heat transport equation. Damageability of the strand has been evaluated based on four fracture criterions.
A. Gołdasz and Z. Malinowski
In this study, a method of determining the heat flux, which reaches the surface of a charge, has been presented with the use of an inverse analysis. The research on the heating process of a square 15HM steel charge was conducted in a natural gas-fired laboratory furnace. The inverse solution was based on the search of the minimum standard error between the measured and the calculated temperatures. The temperature of the charge has been calculated by the finite element method, solving the heat conduction equation for a square charge heated on all the surfaces. As a result, the mean value of the heat flux on each of the heated surfaces of the charge was estimated.
A. Gołdasz, Z. Malinowski, B. Hadała and M. Rywotycki
The paper presents a mathematical model of heat transfer during cooling of hot-rolled rails in the reversing mill. The influence of the radiation shield on the temperature of rolled rails has been analyzed. The heat transfer model for cooling a strip covered by the thermal shield has been presented. The two types of shields build of steel and aluminum sheets separated with insulating layer have been studded. Calculations have been performed with self developed software which utilizes the finite element method.
A. Gołdasz and Z. Malinowski
The inverse method was applied to determine the heat flux reaching the charge surface. The inverse solution was based upon finding the minimum of the error norm between the measured and calculated temperatures. The charge temperature field was calculated with the finite element method by solving the heat transfer equation for a square charge made of 15HM steel heated on all its surfaces. On the basis of the mean value of heat flux, the value of the heat transfer coefficient at each surface was determined depending on the surface temperature of the material heated.
M. Rywotycki, Z. Malinowski, J. Giełżecki and A. Gołdasz
The paper presents an attempt of modelling liquid steel motion triggered off by electromagnetic stirring. Steel viscosity was calculated on the basis of temperature field determined with the use of stationary heat conduction equation. Velocity field was determined using Navier-Stokes equations and stream continuity equation. Solution was obtained using the finite element method. The developed model allows to carry out quick simulating calculations of fluid flow. Stationary solution was employed, and this allowed to reduce computation time substantially.
M. Rywotycki, A. Szajding, Z. Malinowski, T. Telejko, A. Gołdasz and M. Beneš
Charge heating in industrial furnaces is a difficult and complex process. There are many physical phenomena which influence heat transfer. At the charge surface heat transfer takes place by radiation and convection. In order to ensure correct operation of the technological system, it is necessary to achieve the required charge temperature in the whole volume and ensure its uniformity.
The influence of selected burner locations inside the furnace on the charge temperature has been analysed. The temperature field and its uniformity in the round charge made of steel for hot open die forging have been analysed. The model and numerical calculations were performed with the ANSYS-Fluent 14.5 package.
M. Rywotycki, Z. Malinowski, K. Miłkowska-Piszczek, A. Gołdasz and B. Hadała
The paper presents the results of research concerning the influence of radiative heat transfer on the strand and mould interface. The four models for determining the heat transfer boundary conditions within the primary cooling zone for the continuous casting process of steel have been presented. A cast slab - with dimensions of 1280×220 mm - has been analysed. Models describing the heat transfer by radiation have been specified and applied in the numerical calculations. The problem has been solved by applying the finite element method and the self-developed software. The simulation results, along with their analysis, have been presented. The developed models have been verified based on the data obtained from the measurements at the industrial facility.
A. Gołdasz, Z. Malinowski, T. Telejko, A. Buczek, M. Rywotycki, R. Martynowski and D. Kowalski
The study presents the findings of research on developing heating curves of heavy parts for the open die forging process. Hot ingots are heated in a chamber furnace. The heating process of 10, 30, 50 Mg ingots was analyzed. In addition, bearing in mind their high susceptibility to fracture, the ingots were sorted into 3 heating groups, for which the initial furnace temperature was specified. The calculations were performed with self developed software Wlewek utilizing the finite element method for the temperature, stress and strain field computations.