Volume 6, Issue 2 (February 2009)
Quenchant Characterization by Cooling Curve Analysis
Currently, ASTM cooling curve analysis standards ASTM D6200 “Standard Test Method for Determination of Cooling Characteristics of Quench Oils by Cooling Curve Analysis,” D6482 “Standard Test Method for Determination of Cooling Characteristics of Aqueous Polymer Quenchants by Cooling Curve Analysis with Agitation,” and D6549 “Standard Test Method for Determination of Cooling Characteristics of Quenching by Cooling Curve Analysis with Agitation (Drayton Unit),” describe the experimental methodology for cooling curve data acquisition but leave the analysis of the resulting time-temperature cooling data up to the user. Therefore, it is of interest to provide an overview of the various methodologies that may be used by the user of these standards for data analyses and reporting. This is important in order to assess the impact of quench severity on resulting metallurgical properties of various steel alloys. The objective of this paper is to provide a general overview of approaches used to quantify not only the time-temperature behavior, but also a general quantitative assessment of relative quench severity exhibited by the various quenching media being analyzed. Methods for characterizing and interpreting cooling time-temperature curves are reviewed and the reasons for their utilization are discussed.