Study On The Surface Of Steel Billet Base On Rolling And Heating Conditions

Heating and rolling are the main processes of hot rolling production.Combined effect of high temperature and oxidation atmosphere.Iron oxide is oxidized and produced on the surface.This has always been a difficult problem that affects the surface quality of strip.While wasting a lot of resources, the qualified rate of hot rolled coil is reduced.Therefore, how to study the formation mechanism of the oxide scale and how to control the formation of the oxide scale, has become a topic of concern for many researchers.In this study, the siIiconsteelwithnon—orientedgrain 50AW80, carbon structural steel Q235 B and Galvanized sheet steel DX51D+Z steel, which is a non oriented silicon steel, which is more serious in the actual production, are studied,Experimental method is used to simulate the research under different production conditions of ferric oxide formation rules, the macro photo comparison analysis, XRD, SEM / EDS testing means testing samples under different conditions of ferric oxide macro / micro morphology changes.The oxidation thickness curves of 50AW80 steel, Q235 B steel and DX51D+Z steel were determined.From the oxidation time point of view, the rapid oxidation phase(oxidation time <5 minutes), oxidation thickening and heating time is linear relationship.After entering the uniform oxidation stage(oxidation time >5 minutes), the oxidation thickening and heating time was parabolic relationship.Comparison of the three kinds of steel under different temperature thickening curve and knowable 900 ? containing higher amount of carbon oxidation more serious, and 900 ? C due to carbon oxidation reverse reaction containing carbon highest DX51D+Z steel oxide thickness less than of Q235 B steel.Using the method of mathematical regression to get the activation energy of 50AW80 steel Q235 B, the activation energy of 426.338kJ/mol steel is 103.508kJ/mol, and the activation energy of DX51D+Z steel is 148.153kJ/mol.Heating time, heating the atmosphere, at the beginning of the heating temperature for three effect of heating furnace iron oxide scale formation factors, available through analyzing the oxide thickening curve, the heating of the atmosphere than heating time is greater than the initial heating temperature, which is closer to the optimum heating system provides a theoretical basis.1200 ? below the surface oxide is dark gray or grayish, bubbling and pitting local scale, easy to peel,The 50AW80 steel is heated by the Si element, which is not only enriched in the "ridge" process at the oxide grain boundaries at the oxide / substrate interface, but also enriched with the bead like processes.Section analysis indicates that Si is mainly distributed in matrix oxide skin and oxide skin and matrix interface at and easy to oxidation and Si and with FeO composite generation iron olivine phase fe2sio4 of low melting point and the liquid flow characteristics have good corresponding relationship...