Microstructure and mechanical properties of a novel cast multi-phase stainless steel

Cast stainless steels with high strength and toughness are very important for industrial production, but the strengthening methods are very limited. In this study, a novel cast multi-phase stainless steel (CMPSS) containing ferrite, martensite and austenite was prepared and its strengthening mechanism was investigated. After solid solution and tempering at 520 degrees C for 4 h, the yield strength of the sample reaches over 800 MPa, and the total elongation exceeds 13%. This tempering strengthening is mainly achieved by precipitation of the nanoscale Laves phase pinning dislocations in ferrite. However, when prolonging the tempering time or increasing the tempering temperature, the Laves-phase particles precipitate and coarsen along the phase boundary, which seriously damages the strength and toughness of the sample. In addition, high-temperature tempering also leads to a decrease in retained austenite (RA) content by reducing the amount of C and Mn elements in the lath martensite and promotes the precipitation of the R phase (molybdenum-rich intermetallic compound) in ferrite, which is also detrimental to the mechanical properties of CMPSS. (c) 2022 The Authors. 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

A novel cast multi-phase stainless steel (CMPSS) with ferrite, martensite, and austenite was prepared. The solid solution and tempering treatment resulted in high strength and toughness, with the precipitation of nanoscale Laves phase causing dislocation pinning in ferrite. However, prolonged tempering time or increased tempering temperature led to coarse precipitation of Laves phase along the phase boundary, damaging the strength and toughness. High-temperature tempering also reduced the retained austenite content and promoted the precipitation of the R phase in ferrite, negatively affecting the mechanical properties of CMPSS.