Statistical Comparisons of Four (4) Different Thermal Analysis Sample Cup Types for Chemistry Control of Ductile Base Iron

Abstract

The use of thermal analysis as a tool for the real-time chemistry control of carbon and silicon in ductile base iron is very important for seamless melt productivity by avoiding delays in waiting for laboratory analyses of those elements by the direct but time-consuming methods via spectrometer or combustion. With the standard market availability of four (4) different thermal analysis cup types encompassing the two binary choices of ‘round versus square’ and ‘plain versus tellurium’ in amounting to the four choices, thorough comparative testing of each cup type was conducted for gage repeatability and reproducibility (GR & R) analyses and other correlativity analyses. Major results of this testing and data analysis are presented herein along with discussion and conclusions regarding the relative merits of each of the four available cup types. Based on comparative GR&R analyses and subsequent regression analysis of the data, it is concluded that, among the four (4) thermal analysis cup types to choose from for real-time control of the carbon equivalent, carbon and silicon contents of ductile base iron, the ‘RD–PL’ (round and plain) and ‘SQ–TE’ (square and tellurium) cups perform superiorly to the ‘RD–TE’ (round and tellurium) and ‘SQ–PL’ (square and plain) cups.