The factors affecting on the descaling property of reheated steel slabs have been studied in the plate rolling shop. The frequency of scale defects is closely related to the amount of residual scale on the steel slabs after descaling by the hydraulic scale breaker. It is found in the rolling shop that the amount of the residual scale depends remarkably on the following two factors.
(1) Degree of overheating in the furnace
(2) Surface temperature of the scale on slabs immediately before descaling.
On the other hand, it has been pointed out by many workers that the descaling property of Si-killed steels are worse than semi-killed steels. It is well known that fayalite is formed in the scale of Si-killed steel. In this study the effect of surface temperature of scale on the descaling property is mainly examined. It is found experimentally that the existence of fayalite causes the cracks in the scale during cooling.
It could be concluded that the descaling property tends to be bad for the Si-killed steels when the cracks are formed in the scale before descaling.
