Limitations of standard probes for the measurement of spray quenching

MacKenzie Scott - Quaker Houghton (United States]

Spray quenching is an important technique used to quench parts after induction hardening. It has the advantages of rapid cooling of work pieces, and a repeatable process through the control of spray pattern, quenchant velocity, and pressure. There have been numerous efforts to characterize the heat transfer coefficient as a function of surface temperature in the literature. One method has been to use standard probes used to produce cooling curves for immersion quenchants. However, due to the high surface heat transfer, steep gradients can occur, underestimating the heat transfer coefficient. An examination of these thermal gradients as a function of data acquisition rate and material was accomplished, to determine the proper probe geometry to measure and calculate the resultant heat transfer coefficient was determined.