Metallurgical investigations of steel bar reinforcement used in 17th Century Lohagad Hill Fort, India

A comprehensive study was undertaken to examine the steel architectonic reinforcement employed in the construction of 17th century Lohagad Hill Fort. This investigation encompassed a meticulous analysis involving multiple techniques, including metallography, optical imaging, assessment of potentiodynamic behavior, X-ray diffraction (XRD), and scanning electron microscopy. The outcomes of this investigation revealed compelling evidence of sophisticated technology, to indicate the heat treatment and enhanced resistance to corrosion. Through rigorous metallographic examination, it was established that the examined specimen originated from a solid-state reduction process commonly known as the bloomery process. Following this initial stage, the resultant iron bloom underwent forging procedures within a charcoal-fueled fire, culminating in its final configuration through a precise bending operation. Formation of iron oxides on the steel surface within due course of time make it passive to corrosion.