Analysis of quenching oil performance and heat transfer enhancement method

By metal heat treatment process quenching oil is applied in order to achieve a specific quality of materials and also decrease the risk of tensile stresses, cracking and workpiece distortion. The quenching oil contains base oil and different types of additives according to application requirements. High-performance quenching oils must have very high oxidation and thermal resistance, high flash point, low sludge formation, must be non-staining and possess acceptable heat-transfer characteristics. That can be achieved by proper components selection, both base oils and additives. In this study the results of investigation of physical and chemical properties of new quenching oils are presented. Also, in this paper quenching oils performance characteristics were tested. Quenching experiments according to ISO 9950 standard were performed in order to investigate various methods of heat transfer enhancement. Three sets of experiments were conducted. First, still quenching oil at two temperature levels, 20 and 60 °C was tested. Then, titanium oxide nanoparticles were added to the oil in order to increase its thermal properties. Last set of experiments was conducted under ultrasonic agitation at three different levels of power. The cooling curve analysis showed that temperature had almost no effect in still conditions, while the addition of nanoparticles caused increase in heat transfer at all phases of quenching. Using ultrasonic agitation caused elimination of full film phase and increase in cooling rate. All of the mentioned test sets were used to compare the effect different enhancement methods that would have on quenching of real work pieces.