<p>This study focuses on fabricating iron-based composites inspired by ancient corrosion-resistant structures like the Delhi iron pillar. For this, the directly reduced iron (DRI) is integrated with various percentages of slags (P₂O₅ + SiO₂ and FePO₄ + SiO₂) and some with FePO₄ supplement. Compared to the samples with low and high slag proportions, the sample with an intermediate slag proportion (~ 18%) displays its uniform distribution. Moreover, a sample with ~ 18% P₂O₅ + SiO₂ slag and the carbon-mixed DRI via ball milling (labelled 18S1BM) has resulted in finer slag particles distributed uniformly throughout the microstructure. Microstructural features, especially phosphorus in ferrite matrix, pearlite distribution, slag constituents, proportion, and distribution, have played an essential role in governing the corrosion response of the composites. 18S1BM has the least corrosion current after a longer exposure to humidity. Such improvement is caused by forming a better protective layer (in humidity test), consisting of maximum FeOOH fraction and phosphate.</p>