Microstructure manipulation and strengthening mechanisms of 40Cr steel via trace TiC nanoparticles

Highlights: • TiC nanoparticles offered nucleation sites for γFe and αFe by low lattice misfits. • In situ trace TiC nanoparticles enabled microstructure refinement of 40Cr steel. • More and fine RA were obtained by adding trace TiC nanoparticles. • Excellent strength and toughness were yielded by adding trace TiC nanoparticles. In this study, we propose an innovative method to add trace in situ TiC nanoparticles into 40Cr steel to manipulate its microstructure and mechanical properties. The trace TiC nanoparticle/40Cr steels fabricated using this method exhibited better room- and high-temperature properties than those exhibited by unreinforced 40Cr steel. The yield strength, tensile strength, fracture strain, and impact toughness of the 0.054 wt% TiC nanoparticle/40Cr steel were 1293 MPa, 1460 MPa, 10.4%, and 24.2 J/cm², respectively, which increased by 19.7%, 30.4%, 15.6%, and 33.0% than 40Cr steel. The good combination of strength, ductility, and toughness after adding trace TiC nanoparticles to 40Cr steel was attributed to fine grain strengthening, thermal mismatch strengthening, and second phase strengthening. This research provides a new method for fabricating nanosized ceramic particle-reinforced steel that can be used to develop high-performance steel with high efficiency and low cost.