Investigation on the formation of serrated grain boundaries with grain boundary characteristics in an AISI 316 stainless steel

The formation of serrated grain boundaries (GBs) depending on the GB characteristics has been investigated by using an electron backscattered diffraction (EBSD) technique and a transmission electron microscopy (TEM) in an AISI 316 stainless steel. It was observed that at the early stage of aging treatment, the GB morphology was changed from flat to wavy at random GBs without any indication of M23C6 carbide formation, and no GB serration at special GBs (lower than Σ29) was found. The comparison study on the misorientation angle between two neighboring grains indicated that the occurrence of GB serration at random GBs is attributed to the reduction of the total GB energy. Random GBs with high energy tend to be serrated, resulting in the formation of two segments with lower energies. On the other hands, the special GBs may be less likely to form serrated GBs due to their lower GB energy.