Study On The Descaling And Acid Pickling Process Of Hot-Rolled Silica Steel Plate And Parameter Optimization

Before the pickling process,the hot-rolled steel plate need to descale to remove its oxide film.Acid pickling is usually used to dissolve the oxide film through the reaction between hydrochloric acid and oxide film.But the lack-pickling or over-pickling often occurred in thepickling process of hot-rolled silicon steel plate s and result in product with low quality.To improve the quality of descaling processing and acid pickling technology,some experiments,such as SEM,EDS,metalloscope and pickling experiments and nano indentation tests were used to detect the topographic characteristics,thickness and elasticity modulus of oxide film.The compressive fracture model of oxide film was established using the thin plate theoryand the calculating formula of the critical load under the unstable condition was derived by the difference method.Orthogonal design test method was used to study the effects of four parameters（temperature of acid,concentration of hydrochloric acid,concentration of pickling accelerant and compressive stress caused by bending）on acid pickling rate.By fitting the experiments data,the pickling time were formulated to thethe temperature of acid,concentration of hydrochloric acid and concentration of pickling accelerant.The research results showed the silica steel oxide film contain two layers.The main components of outer layer is Fe₂O₃.While the components of inner layer are FeO,SiO₂ and Fe₃O₄.And the elasticity modulus of oxide film is about 145GPa.The conclusion of orthogonal design test indicated that the most important factor to acid pickling rate is pickling accelerant.Pickling rate increases with the increasing of concentration of pickling accelerant.But the improvement is not obvious till the concentration of pickling accelerant increase to more than 0.3%.This study can be used to improve the quality of descaling processing technology and acid pickling technology in practice.