Determination of Gray Cast Iron Age Strengthening by Nondestructive Methods: Effect of Alloying Elements

Gray cast iron age strengthening is a phenomenon known as a modification of the alloy's structure by iron-nitride precipitation during few days after casting. It generates an evolution of cast iron mechanical properties as a gain of hardness and Young's modulus. In a first time, this article presents the possibility to monitor the aging time and the intensity of age strengthening using two nondestructive methods: nonstandard Rockwell hardness and inert frequencies measurement. In a second time, the study shows the influence of the alloying elements on this phenomenon and particularly the influence of free nitrogen amount, which is a first-order parameter to control aging. Finally, a prediction model of the time and the intensity of age strengthening has been elaborated using the results of the two different monitoring described.