Influence of Ageing and Contamination of Polymer Quenchants on Cooling Characteristics

Abstract

The quenching operation is a critical part of the heat treatment process. The cooling characteristics of a quenchant will change during its working life. Improper quenching parameters and the drifting of the cooling characteristics can cause unforeseen costs if a malfunctioning component necessitates additional operations, e. g. straightening, machining, rework, or even rejection. For a polymer quenchant the cooling characteristics are influenced by, inter alia, concentration, agitation, temperature, thermal degradation, contamination and drag-out. In this study tests have been performed in order to study how the ageing and contamination of polymer quenchants influence the cooling characteristics. Polymers used for induction hardening in showers as well as in quench baths have been evaluated with regard to e.g cooling curves, refractive index and kinematic viscosity after ageing. Quenchants used in industrial applications have been evaluated. Cooling curves have been evaluated by using the ivf SmartQuench™ system. This is a tool for testing quenching media, primarily against the current ISO and ASTM standards for hardening oils and polymers. A large number of characteristics are recorded or calculated, such as cooling times to certain temperatures and cooling rates at these temperatures.