Entropy modeling on serrated flows in carburized steels

Samples comprised of carburized steel alloys, 4615, 4720, and 10B22, were tension tested at room temperature and at a strain rate of 2 x 10(-4) S-1. The serrated-flow behavior was modeled and analyzed, using the refined composite multiscale entropy (RCMSE) method. High energy X-ray diffraction revealed the body-centered-cubic (BCC) structure of the three alloys in the as-received condition. Moreover, Vickers-hardness experiments were performed, which showed an increase in the hardness of the alloy that corresponded to increasing impurity concentrations. Here the diffusion coefficient of carbon in the three alloys were estimated, respectively, to be 2.5 x 10(-11) M-2 is 5.1 x 10(-11) M-2/S and 2.8 x 10(-11) m(2)/s for alloys, 10B22, 4615, and 4720, respectively, which agree with the values found in the literature for a-iron. Moreover, the sample entropy, on average, increased with respect to the heating time, and, consequently, the amount of carbon that had diffused into the alloy. The above results show that the complexity of the serration behavior in the alloys studied increases with respect to the amount of carbon that has diffused into the material.