Study On High Temperature Oxidation Behavior And Oxide Scale Control Of Environmental High Carbon Steel Wire Rod 82B

With the increasingly severe environmental problems,the traditional pickling descaling technology is limited in the wire rod industry,and then many enterprises have adopted mechanical descaling instead of pickling descaling.Mechanical peeling descaling technology is to make the wire deformed repeatedly through one or more groups of bending rolls,resulting in the fracture and peeling of oxide scale,to achieve the removal of oxide scale.The technology has gradually become a new trend of wire rod industry development.Mechanical peeling descaling puts forward new requirements for the thickness and structure of oxide scale of wire.However,unreasonable control of oxide scale often causes the poor effect of mechanical shelling of high carbon steel wire rod.In this case,the oxide scale cannot flake in big sheet or strip,even the residual scale on the surface is not easy to remove,which causes damage to mold and surface defects of the wire in the subsequent drawing process,and then severe decreases the quality of wire rod products and cannot meet the use requirements of the downstream customers.Therefore,it is the focus of attention in the wire rod industry to realize the reasonable control of oxide scale and then improve the mechanical peeling performance of high carbon steel wire rod.In view of the situation,thermal gravimetric analyzer,laser confocal microscope,thermal simulated test machine,scanning electron microscope and electron probe micro-analyzer were used to study high temperature evolution behavior of high carbon steel wire rod 82B and investigate evolution law of oxide scale during hot rolling and the effects of laying temperature and cooling process on the oxide scale of experiment steel,and then the industrial trial production was conducted on the basis of theoretical research in the laboratory.The main research work and innovation of this paper are as follows:(1)Oxidation kinetics experiment was conducted using thermal gravimetric analyzer to analyze the oxidation kinetics and evolution law of oxide scale of experimental steel.Oxidation mass gain curves at different temperatures were obtained,indicating that the mass gain followed linear law at 1050?1150? and parabolic law above 1200?.The morphological changes of oxide scale analyzed by using SEM and EPMA indicates the different surface and cross-sectional morphologies of oxide scale at different temperatures.(2)In situ observation of heating oxidation process of experimental steel was conducted using laser confocal microscope to analyze the evolution law of surface morphology of oxide scale,indicating that cracks in oxide scale propagate and heal with grain growth of oxide scale at 900?950?.Combined with high temperature oxidation kinetics,the blistering mechanism of oxide scale was analyzed.The nucleation condition of bubbles is dominated by the adhesion of scale/substrate interface,and then cyclic redox reactions at the interface promote the growth of bubbles.(3)The hot deformation behavior of oxide scale during hot rolling was studied using thermal simulated test machine.The results show that the thickness of oxide scale and the ratio of FeO increase significantly with the increasing rolling temperature.The oxide scale is determined to have good thermoplastic and compatible deformation above 950? through the study of different deformation and deformation temperatures.(4)The influences of laying temperature and cooling process on the oxide scale were investigated using thermal simulated test machine.The thickness of oxide scale and the ratio of FeO increase significantly with the increase of laying temperature.In addition,with the increase of the cooling rate in the middle section,the proeutectoid transition is inhibited,and the proportion and size of proeutectoid Fe3O4 decrease gradually.(5)Based on the results of research in the laboratory and the actual conditions in the industry,the production process of high carbon steel wire rod 82B was optimized and designed.The results of industrial trial production show that the thickness of oxide scale and the ratio of FeO which is also the main structure in the oxide scale decreases,and the interface flatness between the scale and substrate is improved.The tracking results show that the mechanical peeling performance of 82B produced by the new process has been greatly improved to meet the requirements of downstream customers.