Analysis of variant-pairing tendencies in lenticular martensite microstructures based on rank-1 connection

• Main Authors: Yuri Shinohara, Satomu Akabane, Tomonari Inamura
• Format: Article
• Language: English
• Published: Nature Publishing Group 2021-07-01
• Series: Scientific Reports
• Online Access: https://doi.org/10.1038/s41598-021-93514-z

Abstract Herein, variant-pairing tendencies of lenticular martensite in an Fe–30Ni–0.3C (wt%) alloy are analyzed based on rank-1 connection at martensite/martensite junction planes (JPs) to facilitate the understanding of martensite microstructure. The degree of incompatibility (θ) at the JPs successfully explained their observed frequency; in the actual microstructure, variant pairs with a small θ form preferentially. The experimentally obtained JPs were consistent with theoretical ones. To the best of our knowledge, this is the first study to confirm the validity of variant-pair crystallography in steel based on rank-1 connection, both theoretically and experimentally. Diamond, composite-spear, and composite-kink clusters are considered. The cumulative θ at the JPs can suppress diamond cluster formation because it exceeds the θ of a single variant pair, and the diamond cluster is not observed experimentally. However, θ at the JPs cancel out in composite-spear (CS) and composite-kink (CK) clusters, but CK clusters are rarely observed experimentally, while a few CS clusters are observed. This demonstrates the analytical limitations of 2D approaches used to evaluate the frequency of variant pairs and clusters. These two variant clusters have a narrow window of 2D observation because the orientation relationships between JPs and intersection lines between two habit planes affect the areas of JPs.