Factors Influencing Pickling Quality and Speed of Oxide Scale on Hot Rolled Strip

Effects of surface appearance,thickness,roughness and microstructure of the oxide scale of SPHC hot rolled strip on the quality and speed of pickling were analyzed using SEM and surface roughness measurer.How to improve the pickling quality of the oxide scale by reforming the pickling process was studied.The results showed that making cracks and decreasing the thickness of the oxide scale could improve the pickling speed,and increase the thickness eveness and decrease the surface roughness could reduce the surface gray defect.The pickling speed of quick cooled scale with two layers structure was quicker than that of slow cooled scale.When 6%HCl was used,the proper temperature of preheated strip was about 60 ℃ and the pickling time could be reduced.When 18%HCl was used,the temperature of HCl solution was about 75-85 ℃,and the pickling time could be reduced obviously.