Study On The Mechanism Of High Temperature Oxidation Burning Loss Of Q235B Steel Block

At present,it is inevitable to produce iron oxide scale in the process of heat treatment of steel plate in heating furnace.The oxidation burning rate of steel in the heating process of domestic steel rolling heating furnace is generally 1.5%,which causes the loss and even exceeds the economic loss of fuel consumption.At the same time,it will bring other adverse effects such as reducing the yield of slab,high gas consumption,more slag cleaning times of heating furnace,and affecting the heating quality Therefore,the research on how to reduce the oxidation burning loss of steel billet is very necessary undoubtedly.If the annual oxidation and burning loss of domestic steel plants can be reduced by 0.6%,the economic loss will be reduced by about 50 million.Therefore,it is of great practical significance and economic benefit to reduce the oxidation and burning loss of steel plate in the process of hot forming,In order to explore the mechanism of affecting its oxidation and further reduce the amount of scale formation,The related experiments are carried out,which include the simulation experiment research with Gambit?Ansys Workbench and Fluent and the experiment research to use the tube resistance furnace in the laboratory to simulate the industrial heating furnace.The simulation experiments are as follows:(1)the flame shape's research of the double fuel inlet and the single pressure outlet;(2)the simulation experiment of the single billet heated in the heating furnace;(3)the simulation experiments of 33 billets heated in the heating furnace.In Experiment one,a group of developing flame temperature nephograms is obtained,which have symmetrical beauty;in Experiment two,the billet is fully heated and evenly heated;in Experiment three,the simulation result shows the temperature distribution characteristics in the furnace:heating section>soaking section>preheating section.This paper's main part is about the laboratory's tube resistance furnace which is selected to simulate the industrial heating furnace,and the oxidation weight gain test of billet is carried out.By controlling the three key variables of target temperature,holding time and oxidation atmosphere,the orthogonal experiment was carried out,and it was found that the weight gain of oxidation was positively related to the target temperature and holding time,and increases with the higher concentration of oxidizing gas.By Observing oxidized sample after probe preparation with SEM,the results show that the thickness of iron sheet increases with the increase of target temperature,the increase of time in furnace and the stronger oxidation of gas in furnace.These data further verified the positive correlation between the amount of scale and target temperature,the overall time in furnace and the concentration of oxidizing gas.In order to remove the scale,it is necessary to understand its properties,and the properties of substances are determined by its composition.Through XRD analysis,it is found that the iron sheet has three components of Fe O,Fe₂O₃ and Fe₃O₄.Through the analysis of five points on the section of iron sheet by EDS,it is estimated that from the outermost of iron sheet to the steel matrix,the iron atom takes up more and more proportion.The outermost layer of iron sheet is the mixture of Fe₂O₃ and Fe₃O₄,and then the mixture of Fe₃O₄ and Fe O,pure Fe O compound,Fe O and iron matrix.Two methods,mechanical removal and dilute sulfuric acid pickling,are used to remove the iron sheet in the laboratory.The average mechanical removal rate is 8.5%,and the pickling rate is 0.21%when the acid pickling is moderate.Therefore,high pressure water dephosphorization and anti-oxidation coating are introduced in the paper.