The analysis of cooling curves obtained by immersing a probe in the quench medium has been widely used since its availability. For instance, methods described in standards such as ISO 9950 and ASTM D 6482 refer to the use of an Inconel 600 specimen which is quenched to obtain the cooling curve of a given fluid; however, spray quenching is being mostly used in induction hardening processes. In this work, the quenching characteristics of a PAG polymer at 6 and 12 % concentration were determined and compared with water as a baseline. The fluid was heated at 30 °C, while the solution flow rate was set at 90 L/min; two different quenching rings were designed and used in a laboratory-scale setting. Also, the fluid flow in the quench rings was simulated through Computational Fluid Dynamics (CFD), to obtain flow patterns inside the quenching devices. From the results obtained, the cooling rate curves showed no vapor phase, and the maximum cooling rate was found to be higher in one of the quench ring designs. The design of the quench ring device has a significant influence on the quenching characteristics of the quenchant, mainly at medium and low temperatures of the cooling rate curve.

In induction hardening, contamination is a common occurrence. Many parts are processed per hour, with each part carrying a small amount of contaminant. The contaminant could be cleaners, coolants, or machine swarf. Contamination is compounded by the fact that many induction systems have a very small quench tank – often 100-200 gallons. The common question is, at what point does contamination affect the cooling curve or heat extraction behavior of the quenchant? The purpose of this paper is to examine common contaminants and their effects on cooling curve behavior.