Effect of thermomechanical processing on anisotropic behavior of low-carbon steel

• With increasing the annealing temperature and time, the fraction of RX grains increased. • With increasing the annealing temperature and time, γ-fiber texture was weakened. • 600–20 and 700–10 samples with bimodal microstructure showed isotropic behavior. • 600°C samples revealed a higher initial strain-hardening rate than 700°C. • Increment in temperature and time was accompanied by more necking and dimples. This study aims to investigate the microstructural and texture evolution and the anisotropy of cold-rolled and partially annealed low-carbon steel sheets. The samples were produced by 75% cold rolling and subsequent annealing at 600°C and 700°C for 5, 10, and 20 min. By increasing the holding time at 600°C and 700°C, the fraction of recrystallized grains and the average grain size increased. The initial intense γ-fiber, which was developed after rolling, was diminished after recrystallization and gave rise to other non-rolling orientations. The hardness values were reduced from 235.7 to 201.6 HV in 600°C samples by increasing the holding time from 5 to 20 min. The engineering stress-strain curves revealed tensile strength reduction by increasing the annealing time for 600°C samples from the maximum amount of 767.9 MPa to the minimum of 502.3 MPa. This was also observed for 700°C samples, with the highest tensile strength of 578.4 MPa and the lowest tensile strength of 466.1 MPa. The reduction in the tensile strength resulted in the enhancement of ductility. The 600–20 and 700–10 samples revealed near isotropic behavior due to their weak texture. The strain-hardening rate plots exhibited a higher initial strain-hardening rate for the 600°C samples followed by a sharp decrease in the first stage. Finally, increasing the annealing time and temperature increased the fraction of dimples and reduced the cleavage facets, resulting in more ductile fracture.