The Research On Influencing Factors Of Iaron Oxide Scal Of Hot Rolling Strip Steel

Hot rolling is the key technology of plate and strip production.There are many factors affecting the surface quality of hot rolled strip,such as skin Alice,scratch,pressed in scale and pore etc.The scale of pressing and pore surface is difficult to control the quality of the steel.In the hot rolling strip production process,it is inevitable to form an oxide scale on the surface of the steel plate.Iron oxide not only affects the whole strip surface quality and descaling effect,but also affects the coating and corrosion resistance such as surface treatment mechanism,meanwhile also a serious impact on the performance of cold rolled prod ucts.So it is very important to study the properties and control technology of hot rolled strip.Firstly,the oxidation kinetics of three kinds of hot rolled steel is studied.The design of the experiment,as well as the analysis of the experimental results are given.Under the same oxidation time,the oxidation weight gain of each sample increases with the increase of oxidation temperature.Under the same oxidation temperature,the oxidation weight of each sample increases with time.Under the same oxidation time,the oxidation weight gain of each sample increases with the increase of oxidation temperature.Under the same oxidation temperature,the oxidation increases following with time.At the same time,the weight gain curve of each sample has always maintained a high growth rate,which indicates that the oxide layer has not completely covered the surface of the steel substrate during the experimental time.Secondly,the effects of different conditions such as opening temperature,final rolling temperature and coiling temperature on the iron oxide scale of the experimental steel are studied.On the experimental surface,increasing with the rolling temperature,the total thickness of the three kinds of experimental steel is increased,the thickness of Fe₂O₃ is decreased,the thickness of FeO is increased,and the change of Fe₃O₄ is small.Meanwhile,with the increase of the rolling temperature,the area of Fe₂O₃ is significantly reduced,the area of FeO is significantly increased,and the change of Fe₃O₄ is small.With the increase of the final rolling temperature,the steel SS400-Cr the total thickness of the oxide scale increases and tends to be stable,Fe₂O₃ thickness and Fe₃O₄ thickness have the similar trend,because the FeO thickness is very small,the change of the reference significance of small experimental steel SPHC and HP295 is small;the total thickness of the oxide scale is first increased and then decreased,Fe 2O3 thickness and Fe₃O₄ thickness also has a similar trend.The higher the coiling te mperature,the thicker the iron oxide scale.At about 450 ?,the total thickness of the oxidized iron sheet tends to be stable.With the extension of the coiling time,the total thickness of the oxidized iron sheet increases slightly and tends to be stable.Finally,the effects of the temperature of the coil,the concentration of the hydrochloric acid and the temperature of the hydrochloric acid on the pickling time are studied.The surface of steel for all samples,the coiling temperature is 450 ? for pickling time temperature than the volume for the pickling time of its 650 ? should be short,that will take the formation of iron oxide is difficult to pickling steel samples at 650 ?,thus increases the difficulty of pickling,pickling time need more long.For all samples of steel,with the increase of the acid concentration,the pickling time will gradually decrease and tend to be constant.This constant is different for different samples.For the same kind of sample steel,when the temperature of the coiling temperature is high,the constant should be larger than that of the corresponding constant when the coiling temperature is low.When the temperature of the pickling is 60 ?,the acid concentration is better between 15%¹8%.