Effect of gadolinium on the anisotropic tensile properties of a forged high sulfur steel through in-situ tensile experiment

• In-situ SEM tensile testing reveals that elongated MnS inclusions induce significant anisotropy in forged high-sulfur steel, reducing tensile strength from 454 MPa (parallel) to 402 MPa (perpendicular). • Addition of 730 ppm gadolinium increases tensile strength to 468 MPa (parallel) and 446 MPa (perpendicular), effectively mitigating anisotropy. • Failure mechanism depends on loading direction: MnS inclusions fracture and detach under parallel loading, while interface debonding creates elongated voids under perpendicular loading. • Gadolinium modifies MnS into spherical Gd–S inclusions, improving the isotropic mechanical response and overall tensile performance of high-sulfur steels.