The effects of silicon and aluminium contents of a low alloy hot rolled steel sheet on pickling behaviour have been investigated. The experimental methods include laboratory pickling tests in hydrochloric acid and analyses of the oxide scales. The resultsindicate that, as the silicon content increased from 0·5 to 2%, the amount ofFeO required to combine with SiO2 to form Fe2SiO4 at high temperature also increased and that of transformed Fe3O4 at room temperature was reduced. The pickling rate was thus slightly promoted. However, an addition of 0·4%AI was detrimental to pickling because of the formation of segregated FeAl2O4 at the scale/base metal interface.
