Effect of Mo on Microstructure, Texture and Mechanical Properties of Extra-Low Carbon Steel

Steel recycling helps to preserve natural resources, reduce CO₂ emissions, and lower manufacturing costs. One side effect of recycling is that the massive use of steel scrap leads to increased concentrations of tramp elements, which can modify mechanical properties of final products. Therefore, critical concentrations of such elements and their effects on properties must be established. In this study, the influence of 0.02-0.09 wt.% Mo on the microstructure, texture and mechanical properties have been investigated for extra-low carbon (ELC) steel. It is found that although the microstructure and texture of this steel after 80% cold rolling are similar in samples with different concentrations of Mo, the rate of recrystallization, average recrystallized grain size and the area fraction of the γ-fiber in the annealing texture decrease with increasing Mo content. Analysis of a partially recrystallized microstructure indicates that frequencies of nucleated grains having either orientations along the γ-fiber or random orientations are higher than the frequency of grains having orientations along the α-fiber. Furthermore, it is found that hardness and strength of fully recrystallized samples increase, while n- and r-values decrease with increasing Mo content. The results obtained suggest that the presence of up to 0.02 wt.% Mo can be tolerated in recycled ELC steel for applications where high drawability is required.