Reduction of oxide scale on hot-rolled steel by hydrogen at low temperature

This study was carried out with an intention to remove the oxide scale on hot-rolled steel by gaseous reduction instead of traditional acid pickling method with an aim to reduce the pollution. The reduction of iron oxide scale by hydrogen-argon mixture was studied by thermogravimetric tests in the temperature range of 370-550 °C. The rate controlling process was discussed according to the Avrami-Erofe'ev equation generalized method. The analysis suggests that the reduction of scale is controlled by two- and/or three-dimensional growth of nuclei in the whole temperature range investigated. The apparent activation energy exhibit a sudden decrease from 78.8 to 31.8 kJ/mol at temperature higher than 410 °C. Morphological structure of the reduced scale was investigated by scanning electron microscope.