Mechanical performance and fracture behaviour of dissimilar welds made of thermo-mechanically rolled steels : a study of dissimilar steel grades weld joint between S700 MC Plus, and Domex 500 D

Abstract

Steel is one of the most widely used engineering materials, with applications ranging from offshore, onshore, airborne and space technologies. Such dependency on steel can be attributed to its remarkable strength-to-weight ratio and its versatility which allows engineers to customize its strength according to their needs, thus enabling them to confidently propose steel as the preferred material before any physical manifestation of the conceptual design. Thermo-mechanically controlled processing (TMCP), a steel production routes, employs controlled heating and cooling aided by grain refiner and mechanical deformation to optimize steel's microstructure and enhance its strength. Combining TMCP steels in dissimilar welding reduces weight while strengthening the overall structural performance and indirectly lowers global emission associate with steel production. Dissimilar welds or welds between steels with varying chemical compositions or mechanical properties are technically challenging yet they are being increasingly used in corrosive environments and high-temperature applications. When executed with precision, they result robust structure that minimize capital investment and optimize both material use and structural performance, benefiting both engineers and project stakeholders. In this paper, dissimilar welds between two thermo-mechanically processed steels, namely, Strenx 700 MC Plus and Domex 500 MC D, were investigated to examine weldment metallurgy, the HAZ region and fracture behaviour. Conclusions have been made to obtain optimum welding parameters by characterizing microstructure, and analysing mechanical properties and fracture behaviour while also providing experimental resources about the design of dissimilar welds.