Cooling Characteristic of Polymeric Quenchant: Calculation of HTC and Prediction of Microstructure and Hardness

Abstract

The present paper discusses the influence of experimental conditions on the quenching performance of poly(2-ethyl-2-oxazoline) (PEOX) aqueous solutions used as cooling medium, using a standard ISO Inconel alloy probe for measurements of cooling rate. The evaluation procedure is demonstrated on characterization of cooling power of water-based polymer (PEOX) solutions by using different concentration, temperatures, and agitation conditions of the cooling media. The results show that the different experimental conditions have a significant effect on the cooling performance. The polymer quenching mechanism and the comparative cooling characteristics of water, and water-based PEOX polymer solution with concentrations from 2.5 to 15 wt.% were discussed. The study involved the assessment of the quenching severity by calculating the hardening power (HP) via empirical equations. Calculation of heat transfer coefficients as well as prediction of microstructural constituents and the hardness profile in a cross-section of steel sample were carried out on the basis of inverse calculation from the recorded cooling curve.

Evaluation of the characteristics of an AISI 1045 steel quenched in different concentration of polymer solutions of polyvinylpyrrolidone

“…However, polymers that do not present average solubility in water present a gradient of polymer concentration towards the interface between liquid and vapor. In these situations, the rupture of the steam film is sudden, causing the extraction of more uniform heat, which is followed by boiling, initiated by the base of the specimen 8 , 9 .…”

Analysis of the applicability of polymeric solutions as cooling fluid in the quenching of low-alloy steels

“…Polymeric cooling media have advantages over traditional fluids since they are biodegradable and have low levels of toxicity, flammability [18,21,23,29]. However, one of the most important aspects is the mechanism of breaking the vapor layer, which collapses instantly throughout the body.…”

“…Usually, the greater the amount of polymer in the fluid, the thicker the vapor blanket becomes, making it difficult to break. Therefore, the lower the concentration of the solution, the greater its heat exchange capacity, consequently causing higher levels of hardness and mechanical resistance [16][17][18][19][20][21][22][23][24][25][26][27][28][29].…”

Investigation on the capacity of PVP polymer in tool steel cooling in the quenching process

“…Because of this, there is no gradient of thermal exchange throughout the body, which results in minimized residual stresses and greater uniformity of properties throughout the part. These solutions present high flexibility in the process, since the concentration of polymer in the water considerably alters the heat removal capacity of the material [12]. The increase in concentration causes loss of heat exchange capacity, since they increase the viscosity of the refrigerant, because they make the vapor layer thicker and more stable.…”