Cooling Curve Analysis as an Alternative to Dilatometry in Continuous Cooling Transformations

Dilatometry and cooling curve analysis (CCA) are two methods of determining the evolution of a phase transformation with temperature. The two methods are similar conceptual in that they take an indirect measure of the transformation and extract phase fraction information from it; however, the differences between the two methods typically makes one method better suited to analyzing a given transformation. However, without a quantitative comparison between the two methods, it is difficult to use them interchangeably. We address this by presenting a quantitative comparison of CCA and dilatometry for a martensitic transformation in a 9Cr3W3CoVNb steel. The resulting phase fraction data matches very well, within 5 K (5 °C) for any given phase fraction. This paper also extends to the quantitative methodology of calorimetry to the analysis of dilatometric data, with results comparable to ASTM A1033-10, but with expected higher accuracy by accounting by variable thermal expansion coefficients.