Quenching with Aqueous Polymer Solutions

Abstract Quenching with aqueous polymer solutions has some distinct advantages over classical oil quenching. Among these are the good environmental properties and the possibility to adjust the quenching performance between oil and water quenching. Nevertheless, critical aspects must also be taken into account. When quenching steel parts with polymer solutions, “explosion-like” phenomena can occur, often accompanied by large cooling rate changes. These “explosions” can lead to pressure waves and vibrations in the quenching tank, which in the long run can even destroy weld seams of the quenching tank. In the framework of a research project, experimental investigations were carried out in a laboratory quenching bath and in an industrial quenching tank. The polymer type, the type of incident flow, the flow velocity, the bath temperature and the size of the test shafts were varied. Near-surface temperature measurements inside the shafts were performed to characterize the resulting quenching processes. Simultaneously, electrical conductivity measurements and audio and video recordings were made to localize insulating films on the surface and their collapse. To systematize and characterize the large number of measurement results, characteristic types of cooling processes and characteristic numbers for their characterization were defined and will be presented in this paper.