Enhancement of Elastic Modulus by TiC Reinforcement in Low-Density Steel

Abstract

The present study investigates the effect of in situ reinforced TiC on the microstructure, density, and tensile properties of austenitic low-density steel. Low-density steels with compositions of Fe-18.93%Mn-6.20%Al-0.76%C (Steel A) and composition of steel A, with the addition of 2.5 %Ti and 0.5 %C are melted via induction melting and cast into copper mold to get austenite in steel A and austenite plus in-situ formation of 4.5 vol% TiC in Steel B, respectively. Both the homogenized steels are subjected to hot rolling followed by solutionizing and quenching in water. The austenitic Steel A reports low density and Young’s modulus of 6.99 g/cc and 169 GPa, respectively. The presence of 4.5 vol% TiC in austenitic Steel B reduces density to 6.84 g/cc but increases Young’s modulus to 176 GPa, yield strength to 578 MPa, and tensile strength to 920 MPa. In situ formation of TiC increases grain boundary strengthening due to refinement in austenite size and dislocation strengthening significantly even though solid solution strengthening is the dominating one. Formation of TiC reduces the product of strength and elongation (PCE) to 32.5 GPa% due to a decrease in ductility. Both steels exhibit Ludwigson flow behavior, characterized by two distinct slopes of easy glide and cross-slip, respectively, in true stress–true strain plots.