Microstructure and Physical Properties of High Modulus Steel

Microstructures and physical properties of high-modulus steel were experimentally investigated. The results indicated that the high-modulus steel consisted of a ferrite matrix (85 vol%) and a bi-modal distribution reinforcement phase of titanium boride(15 vol%),in which primary TiB particles exhibited alath-like morphology and formed a three-dimensional network structure with the eutectic regions. Electron backscatter diffraction (EBSD) analysis revealed that TiB particles predominantly segregated at grain boundaries, forming a three-level hardness gradient system of "matrix–transition phase–hard phase". This configuration enhanced the yield strength through Orowan strengthening and grain-boundary pinning effects. Benefiting from multi-scale synergistic strengthening effect, the high-modulus steel could achieve a 12% increase in elastic modulus (240 GPa) and a 4.8% reduction in density (7.48 g/cm³) while maintaining a tensile strength of 690 MPa and an fracture elongation of 19.5%, thereby obtaining an excellent combination of strength, modulus, and ductility. This microstructural design method provides a new insight for the development of a new generation of high-performance structural materials.