Correlation Between Microstructure and Tensile Properties of Low-Carbon Steel Processed via Different Thermomechanical Routes

The low-carbon steel revealed the presence of ferrite-pearlite and ferrite-martensite microstructures after being subjected to different thermomechanical routes. These routes involved two distinct stages: 1) reheating hot-rolled steel at 1473 K, followed by cooling via step quenching, intermediate quenching, and furnace cooling, and 2) cold rolling and subsequently annealing at 873 K for 2 and 8 h. The quenching schedules finally developed a ferrite-martensite structure with different martensitic morphology, whereas furnace cooling promotes a ferrite-pearlite structure. The prolonged annealing assists in carbide precipitation from deformed ferrite-martensite microstructure while pre-existing carbides coarsen after 8 h of annealing in furnace-cooled specimens. The sudden phase disintegration contributes to the changes in the recrystallized kinetics and evolution of precipitates, tailoring the final grain size. Additionally, the development of textures after cold rolling and annealing is studied through the emergence of & alpha; and & gamma; fiber in BCC phase. Finally, detailed microscopic technique has been employed to correlate the overall tensile response of the investigated samples with their interrelated microstructures.