Classification of martensite-austenite constituents according to its internal morphology in high-strength low alloy steel

A novel internal morphology of martensite-austenite (M-A) constituent in the intercritically-reheated coarse-grained heat-affected zone of an HSLA steel was systematically studied. Previously identified morphologies of M-A were observed on prior austenitic grain boundaries (blocky M-A) with a cored and lath morphologies (Type 1 and 2, respectively), and lath boundaries (slender M-A) with a lath morphology (Type 2). However, this work identified a new morphology, which is with a random arrangement of substructures (Type 3). Due to highly chaotic morphology (more interfaces between substructures), type 3 M-A is more likely detrimental for toughness than the other two. (C) 2020 Elsevier B.V. All rights reserved.