Measurement of the activation energy for the formation of serrated grain boundaries was carried out to understand its underlying formation mechanism in an AISI316 stainless steel. The apparent incubation time necessary to initiate grain boundary serration was obtained at different aging temperatures, and the apparent activation energy for serration was carefully calculated from the Arrhenius relationship between incubation time and aging temperature. The activation energy for grain boundary serrations in this alloy was measured to be approximately 148kJ/mole, which was consistent with the activation energy for lattice diffusion of carbon in γ-iron (142kJ/mol). This result indicates that grain boundary serration could be controlled essentially by the lattice diffusion of carbon to grain boundaries. Based upon the through-thickness observation of serrated grain boundaries, a straight boundary began to serrate from the surface at an early stage of the aging treatment, and then the serrated parts propagated throughout the entire grain boundary.

A Study on the Mechanism of Serrated Grain Boundary Formation in an Austenitic Stainless Steel. K.J.Kim, H.U.Hong, S.W.Nam: Materials Chemistry and Physics, 2011, 126[3], 480-3