QUENCHING OF STEEL PLATES IN SODIUM POLYACRYLATE SOLUTIONS

A photographic study has been made of the appearance of the vapour-liq uid mixture adjacent to the surface of a steel plate cooled in sodium polyacrylate solutions from 850-degrees-C to ambient temperature. This has been correlated with the variation of surface heat transfer coeff icient observed during the quench. Novel structural features in this v apour-liquid mixture included a network pattern of continuous vapour r ising up the plate surface separated by a static layer of froth. This structure was associated with a sudden drop of surface heat transfer c oefficient and is probably responsible for the similarity of the quenc hing characteristics of Aquaquench ACR solutions and quenching oils. I n other respects, this quenchant exhibited typical characteristics, na mely, vapour blanket, nucleate boiling, and convective cooling stages. The duration of the vapour blanket stage increased as the polymer con centration of the solution increased.