Uncovering the superior corrosion resistance of iron made via ancient Indian iron-making practice

Deepak Dwivedi,Jitendra P Mata,Matthew R Rowles,Kateřina Lepková,Thomas Becker,Filomena Salvemini

doi:10.1038/s41598-021-81918-w

Deepak Dwivedi, Jitendra P Mata + Show 4 more

Open Access

https://doi.org/10.1038/s41598-021-81918-w

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Abstract

Ancient Indian iron artefacts have always fascinated researchers due to their excellent corrosion resistance, but the scientific explanation of this feature remains to be elucidated. We have investigated corrosion resistance of iron manufactured according to traditional metallurgical processes by the Indian tribes called ‘Agaria’. Iron samples were recovered from central India (Aamadandh, Korba district, Chhattisgarh). Iron artefacts are investigated using a range of correlative microscopic, spectroscopic, diffraction and tomographic techniques to postulate the hidden mechanisms of superlative corrosion resistance. The importance of manufacturing steps, ingredients involved in Agaria’s iron making process, and post-metal treatment using metal-working operation called hot hammering (forging) is highlighted. This study also hypothesizes the probable protective mechanisms of corrosion resistance of iron. Findings are expected to have a broad impact across multiple disciplines such as archaeology, metallurgy and materials science.

Highlights

Ancient Indian iron artefacts have always fascinated researchers due to their excellent corrosion resistance, but the scientific explanation of this feature remains to be elucidated
We have investigated the iron manufactured using the traditional iron making process followed by Indian tribes known as ‘Agaria’
Our results clearly demonstrated the importance of analytical techniques operating at various length scale, in proposing the mechanisms of corrosion resistance including other properties of archaeomaterials

Summary

Introduction

Ancient Indian iron artefacts have always fascinated researchers due to their excellent corrosion resistance, but the scientific explanation of this feature remains to be elucidated. We have investigated corrosion resistance of iron manufactured according to traditional metallurgical processes by the Indian tribes called ‘Agaria’. The Delhi iron pillar is an important example of tribal tradition (Indian blacksmiths) of iron making in India. Several theories have been postulated regarding corrosion resistance of the Delhi iron pillar Some of those refer to the inherent nature of the construction material, such as the selection of pure iron, presence of slag particles and slag coatings, surface finishing using mechanical operation, phosphate film formation, or the Delhi’s c limate[11,12,13,14,15,16,17]. Agaria tribes are regarded as important tribal community responsible for channelizing the traditional iron and steel making technological growth in various Indian states in the central region, such as Madhya Pradesh and Chhattisgarh, Orissa Eastern part of Uttar Pradesh and Bihar from the ancient times[18].

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