Evolution of grain boundary character distribution in near-surface regions of a cold-rolled nickel-based superalloy during induction heating process

The influence of induction heating on the grain boundary character distribution (GBCD) in near-surface regions of a cold-rolled Nickel-based superalloy was researched. After induction heating, most of low-E coincidence site lattice (CSL) boundaries were Sigma 3 boundaries, which were mainly formed via the growth accident model. Moreover, the grain structures evolution during induction heating had a great influence on the evolution of GBCD. At the low strain of 0.1, both the fraction of Sigma 3 boundaries and grain size increased with the increasing temperatures, while the former was closely related to the better development of grain-clusters at the higher temperature. In addition, the coherent Sigma 3 boundaries were easier to be formed at the higher temperature during induction heating, owing to their low interface energy and mobility. At the large strain of 0.5, the fraction of Sigma 3 boundaries also increased with the increasing temperatures, but the grain size exhibited the opposite trend, which was closely related to the well development of static recrystallization (SRX) behaviors. Meanwhile, there was a symbiotic relationship between the SRX grains and Sigma 3 boundaries during induction heating. Through the electrochemical corrosion tests, it was proved that induction heating can contribute to the improvement of corrosion properties of superalloys via increasing the fraction of Sigma 3 boundaries, while the best corrosion resistance appeared in the samples treated at 800 degrees C with the strain of 0.5. Moreover, the evolution of both Sigma 9 and Sigma 27 boundaries was also closely related to strains and induction heating temperatures, but their fractions were less than 4%. (c) 2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

The influence of induction heating on the grain boundary character distribution in a cold-rolled Nickel-based superalloy was studied. The type of grain boundaries and their distribution were closely related to the evolution of grain structures during induction heating, which was influenced by the heating temperature and strain level.