Quench cooling of fast moving steel plates by water jet impingement

Abstract

Quench cooling of steel on the Run Out Table presents great complexity arising from the high speed of the steel slabs and the violent nature and short time scale that characterize the involved boiling regimes. Until now experimental studies on quenching of moving surfaces have reported surface speeds up to 1.6 m/s. This is far from the real Run Out Table operation conditions, where the steel slabs move between 2 and 22 m/s. In this study, a new experimental setup is presented that allows quenching of steel surfaces at speeds between 0 and 8 m/s. For the first time direct visualization of the boiling activity in the stagnation zone during quenching of a moving surface is presented and the effects of surface speed and water jet temperature are analyzed. The results show a change in the trend of the cooling history and boiling curves that depends on plate speed. This change is a consequence of the effect of surface motion on the viscous and thermal boundary layers. The direct visualization of the stagnation zone confirms that this change in trend corresponds to progressive suppression of boiling activity and enhancement of explosive boiling and film boiling with increasing surface speed.