Study On The Structure Transformation And Acid-pickling Behaviour Of The Oxide Scale On Low Alloy Steel Plates

After the steel strip is hot rolled, reducing coiling temperature and increasing cooling rate have been effective cooling strategy to refine microstructure properties. But the structural development of the Fe O on steel under continuous-cooling conditions and the criteria for producing various types of scale structures under different coiling and coil cooling conditions have not been defined.Therefore, it is a practical project to study about the influence to the structure transformation and pickling properties of coil temperature and cooling rate theoretically.Based on Q345 low alloy steel as the research object in this paper, firstly, temperature expression of each layer cross section node is induced base on the finite difference method in the natural air and wind cooling process. With the the law of conservation of energy, temperature evolution is obtained.Secondly,based on the temperature evolution of strip’s cooling process through thermodynamic calculation, experimentally studying low alloy steel oxide scale transformation rule under the condition of continuous cooling with Gleeble 、metallographic and X-ray analyzer equipment. According to the analysis of experimental results, the change rule of structure and volume percentage under different coiling temperature and cooling speed are obtained. Lastly, based on the experimental results, tansformation of Fe O model for the volume fraction is regressed on the Q345 in the process of continuous cooling.Finally, the pickling behavior of oxide scale about hot rolled low alloy steel is researched with pickling experiment, pickling dynamics calculation model is regressed on the Q345 in the process of continuous cooling. With the SEM, the difference of pickling and macro and micro morphology under different coiling temperature and cooling speed are obtained.