The scanning electron microscope, transmission electron microscope, optical microscope, X-ray diffraction and hardness tests were used to investigate the effect of deformation parameters in unrecrystallization range on microstructural characteristics in Al-bearing hot-rolled transformation-induced plasticity steel. The thermomechanical-controlled processing was carried out with thermomechanical simulation machine, and the samples were compressed to compression strains of 0, 0.15, 0.25 and 0.35 at compression temperatures of 850, 900 and 950 °C. The results showed that the volume fraction of polygonal ferrite increased with the increasing compression strain, while the volume fraction of retained austenite reached the maximum value at compression strain of 0.25. The volume fraction of polygonal ferrite decreased with the increasing compression temperature, whereas the volume fraction of retained austenite possessed the maximum value at compression temperature of 850 °C. Some granular retained austenite was present in uncompressed samples, and some pearlite appeared at large compression strain, while the hardness of the samples exhibited the similar variation tendency to the volume fraction of retained austenite.
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The authors acknowledge the support from National Natural Science Foundation of China (No. 51504063). R.D.K. Misra, an honorary professor, also acknowledges the continued collaboration with Northeastern University by providing guidance to students in research.