Method of removing surface oxide layers of a hot rolled steel

摘要

The present disclosure provides a pickling method for removing the surface oxide of hot rolled steel coils with high Cr and Si contents (Cr is 0.5-9 wt.% and Si 0.5-2.5 wt%). The new pickling formula combines HCl and HNO_3 in water: xHCl+ yHNO_3 +H_2O, where x/(x+y)＞2% and y/(x+y)＞2%. The HCl and HNO_3 concentrations are around 0. 1N-10N and the pH of the solution is kept below 1. The temperature of the pickling solution is kept between 20 °C and 90 °C and the pickling time is between 10 sec and 30 min. A wicking material or a sponge could be used to help apply the chemicals to the steel surface. Other suitable reagent(s) such as sulfuric acid could also be added in the new formula to further improve the oxide removal process.