Spray cooling of extruded EN AW-6082 aluminium alloy sheets: spatial heat transfer coefficients

Quenching profiles during their extrusion with subsequent ageing can increase their strength by a factor of 1.5–2 compared to the as-extruded state. Water-air spray cooling is a quenching technology which allows the desired profile temperature to be reached with high accuracy and which is characterised by low energy demand. To apply this cooling technique correctly, the heat transfer coefficient’s dependence on the surface temperature and properties of the extruded profile, made from EN AW-6082 alloy, and on the spray cooling parameters was determined using the lumped heat capacitance method. The absence of a significant impact of the spraying distance and inclination angle on the average heat transfer coefficient within the investigated range was noted. Dependencies of the relative heat transfer coefficient on the temperature and the distance to the spray axis were derived. It was shown that these dependencies, which can be used for modelling such processes, are practically identical for all considered spraying parameters.