Analysis of oxide scale on hot rolled strip surface and its pickling behavior
In order to study the influence of composition and structure of oxide scale on hot rolled strip on pickling time,ST12 steel,45 steel and DP1180 steel were selected as experimental steels.The macro-morphology,cross-sectional micro-morpholo-gy,oxide layer thickness and main chemical composition of oxide scale on hot rolled strip surface of three steels were analyzed by SEM and XRD,and the pickling time was tested.The results showed that the oxide scales on the surface of ST12 steel and 45 steel hot rolled strip were composed of α-Fe,FeO,Fe3O4 and Fe2O3.There was no Fe2O3 in the oxide scale on the surface of DP1180 steel strip,but a certain amount of Fe2SiO4 was produced.The average thickness of oxide scale on the surface of ST12 steel,45 steel and DP1180 steel strip were 10.88,12.77 and 15.36 pm respectively,and the pickling time were 30.2,23.8 and 16.2 s respectively.Compared with ST12 steel,the content of α-Fe in the oxide scale on the surface of 45 steel strip which was easy to react with acid solution was high,while the content of oxide which was difficult to react with acid solution was less,so its pickling efficiency was higher.The main reason for the shorter pickling time of DP1180 steel strip was that besides the high con-tent of α-Fe in the oxide scale,there were more FeO in the three oxides,and there were gaps between the oxide scale and the steel matrix,which could promote the diffusion and reaction of acid liquid in the oxide scale.Therefore,the pickling efficiency of oxide scale on the surface of hot rolled strip was mainly related to its composition and structure,and the thickness of oxide scale had little influence on it.
hot rolled stripoxide scalecompositionstructurepickling efficiency
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