Adekunle Akanni AdelekePeter Pelumi IkubanniT. A. OrhadahweJ.O. AwedaJamiu Kolawole OdusoteO.O. Agboola2025-01-282019-10-13Adeleke, A.A. et.al. (2019). Microstructural assessment of AISI 1021 steel under rapid cyclic heat treatment process. Results in Engineering, 4(100044).2590-1230https://doi.org/10.1016/j.rineng.2019.100044https://repository.nileuniversity.edu.ng/handle/123456789/279This research was aimed at using image analysis to describe the effects of rapid cyclic heating on mild steel. AISI 1021 steel sample used in this study was subjected to quenching heat treatment followed by 1, 2, 3, and 4-cycles of rapid heat treatment. The as-treated steel samples were characterized by Brinell hardness tests, Charpy V-notch impact tests, optical microscopy, and image analysis using Image J software. The results revealed that the grain size decreased from 1.07 μm in the control sample to 0.79 μm in the third cycle sample and increased to 0.86 μm in the fourth cycle sample. However, the results revealed that two-cycles of rapid heat treatment was enough to produce ultra-fine grains and impact ductility in mild carbon steel. Keywords: Mechanical properties, Collapsed building, Steel rods, Chemical compositions, Percentage elongationenMechanical propertiesCollapsed buildingSteel rodsChemical compositionsPercentage elongationArticle