Effect of microstructures tuning on mechanical properties of an ultra-high strength marine steel via the TRIP effect

In this study, we investigated the impact of microstructures tuning on the mechanical properties of marine steel, focusing on the role of retained austenite (RA) in achieving superior strength-plasticity synergy through the TRIP effect. Our findings reveal that the experimental steel subjected to the two-step bainite treatment exhibits superior comprehensive mechanical properties, which is attributed to the generation of a large amount of film-like RA and small-sized blocky RA by appropriately sacrificing the grain size of the bainite laths. This particular configuration leads to an outstanding combination of strength and plasticity, including a yield strength of 1050 MPa, an ultimate tensile strength of 1350 MPa, and an elongation of 18.5%. These results highlight the importance of microstructure engineering in enhancing advanced high strength steel for marine applications.