Tracking the evolution of intergranular corrosion through twin-related domains in grain boundary networks

Abstract

Tailoring the grain boundary network is desired to improve grain boundary-dependent phenomena such as intergranular corrosion. An important grain boundary network descriptor in heavily twinned microstructures is the twin-related domain, a cluster of twinrelated grains. We indicate the advantages of using twin-related domains and subsequent statistics to provide new insight into how a grain boundary networks respond to intergranular corrosion in a heavily twinned grain boundary engineered 316L stainless steel. The results highlight that intergranular corrosion is typically arrested inside twin-related domains at coherent twins or low-angle grain boundaries. Isolated scenarios exist, however, where intergranular corrosion propagation persists in the grain boundary network through higher-order twin-related boundaries.

Quantitative assessment of the driving force for twin formation utilizing Nye tensor dislocation density mapping

“…This is similar to the popping out model for 66 twin nucleation [9], in which twins form at high energy boundaries in order to reduce the internal 67 energy of the system. It is also consistent with the observation of secondary recrystallization 68 resulting in high fractions of CSLs [17] and twin-related domains [22] under certain conditions. 69…”

“…Empirical methods of grain 20 boundary engineering (GBE) have been developed to enhance the fraction of twin and twin-21 related boundaries [1,[5][6][7]. Understanding twin nucleation and propagation with respect to 22 experimental parameters, such as local strain gradients, is critical for improving the design of 23 processing methods to enhance the properties of structural materials, as the mechanisms by 24 which twins nucleate and propagate during thermomechanical processing are still not well 25 understood. 26…”

“…To test 80 this hypothesis, precession electron diffraction (PED) was used in conjunction with Nye tensor 81 analysis to calculate and map dislocation densities in order to determine localized microstructural 82 conditions required for twin nucleation characterize twin nucleation sites in Cu. While various 83 processing approaches can be used to increase the fraction of twin boundaries, a method based 84 on the low driving force regime is more promising for the production of GBE microstructures 85 with a highly inter-connected Σ3 n grain boundary network [20][21][22]. The results presented in this 86 paper connect twin formation phenomena to local dislocation-based driving force, and thus 87 clarify which of the mechanisms play a role in the formation of twin-related microstructure 88 networks.…”

Sensitization of Austenitic Stainless Steels: Current Developments, Trends, and Future Directions

“…The new approach has been emerged to control sensitization, though crystallographically has also been discussed [22,36]. On the one hand, Fuji et al [22] have shown that the absence of IGC attack at low-angle GBs (misorientation between 5° and 10°) and IGC attack observed low-angle GBs of misorientation between 10° and 15° [22].…”

Additive friction stir deposition: a deformation processing route to metal additive manufacturing

“…The thermomechanical processing nature of AFSD allows for the alteration of intrinsic grain boundary properties too. By controlling the fractions of special grain boundaries, relative connectivity of the special and random grain boundaries, and the perfection of special boundaries compared to coincident site lattice, the resistance against sensitization [75] or hydrogen embrittlement [76] could be significantly improved in AFSD-printed austenitic stainless steels.…”