Feasibility Study Of Metal Electric Heating In Non-uniform Temperature Field

In view of the energy and environmental problems brought about by the rapid development of my country’s iron and steel industry,the existing high-temperature steel rolling heating furnaces have great incompatibility in improving energy efficiency,reducing pollutant emissions,and improving the quality control of rolled steel products,especially Heating of metals with a non-uniform initial temperature distribution in cross section.Therefore,this study intends to develop a metal heating process with direct electric heating by direct current to improve energy efficiency,heating rate and product quality while reducing pollutant emissions.The main content of this research is: Feasibility study of direct electric heating of metal billets with non-uniform initial temperature field distribution.Firstly,based on the basic theory of electrical engineering and heat transfer,a DC self-resistance heating test bench suitable for metal billets with small cross-sections was built,and rapid heating experiments were carried out for typical steel grades.Through the built experimental platform,the distribution law of the heating curve of different steel grades under different ambient temperatures was studied respectively,and it was found that under the same current intensity,different metal steel grades will cause different temperature distributions,and their resistivity varies with the relationship of temperature changes varies.Under different experimental conditions,the heating rate of various metals to achieve rapid heating and the relationship between the resistivity and temperature were obtained.Compared with the heating speed of conventional heating furnace,the feasibility of rapid direct electric heating of metal was proved,and the research basis and experimental comparison were provided for the follow-up research work.Then,ABAQUS software was used to carry out finite element numerical simulation research on the actual metal billet with large size section.The self-resistance heating of metal billets with different non-uniform initial temperature field distributions was explored respectively,and the surface and internal heating processes of metal billets with large cross-sections were studied to determine the temperature distribution law and temperature uniformity inside the metal.In the simulation calculation,it was found by comparison whether the relationship between the resistance and the temperature change was constant during the heating process of the metal,which has different effects on the temperature distribution of each point inside the metal.When the resistivity was constant in the simulation calculation,there was a large error between the distribution of the temperature field and the current density and the results of the resistivity change with temperature,because the relationship between the resistivity of the material and the temperature was nonlinear.Although the change value of resistivity with temperature was limited,the change of resistance value in different temperature ranges was considerable.Finally,the metal heating process of two types(cooling type and heating type)with non-uniform initial temperature distribution was simulated and calculated to explore the influence of different initial temperature distribution on the internal temperature distribution of the metal,and the effect of different current densities on the internal temperature distribution of the metal.The influence of the law,and then analyze and judge the heating process and the end of the heating,the actual size of the non-uniform initial temperature field in the billet and the temperature uniformity on the section of the billet.The simulation research results will provide theoretical and computational basis for the follow-up further industrial experiments.