Meghna Desai https://orcid.org/0000-0002-3018-9735 Thilo Rehren https://orcid.org/0000-0002-9169-1198

Abstract

Pre-industrial crucible steel ingots, produced in both Central and South Asia, are an important class of iron-carbon alloys. Their microstructure reflects their formation from a liquid alloy at a carbon content of 1.0–2.5wt%, which is higher than most mild steels but lower than most cast irons. This article introduces a tool to quantify the carbon content of such alloys based on an operator-supervised image analysis which determines the relative proportions of austenite/pearlite and cementite, respectively, from high-contrast back-scatter electron images of unetched samples. Using examples from a recently discovered hoard of crucible steel ingots in Telangana, south-central India, we demonstrate the capabilities of the tool and test its usefulness. The main benefit is in improving accuracy and precision in metallography-based carbon content determination in such alloys by reducing the uncertainty in area estimation in complex microstructures based on visual impression alone.

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References
Alaa N and Abidne El I Z 2021, Image processing with Python: An introduction. LAMAI Laboratory FST, Cadi Ayyad University (Marrakech).
Czarski A, Skowronek T, and Matusiewicz P 2015, ‘Stability of a lamellar structure – effect of the true interlamellar spacing on the durability of a pearlite colony’, Archives of Metallurgy and Materials 60, 2499–2503. https://doi.org/10.1515/amm-2015-0405.
Das G 1999, ‘Image analysis in quantitative metallography’ in G Sridhar, S Ghosh Chowdhuny and N G Goswami (eds), Materials characterization techniques, principles and applications (NML Jamshedpur), 135–150.
Doane D and Seward LE 2011, ‘Measuring skewness: A forgotten statistic?’ Journal of Statistics Education 19(2). https://doi.org/10.1080/10691898.2011.11889611.
Ferrer-Eres M A, Peris-Vicente J, Valle-Algarra F M, Gimeno-Adelantado J V, Sanchez-Ramos S, and Soriano-Pinol M D 2010, ‘Archaeopolymetallurgical study of materials from an Iberian culture site in Spain by scanning electron microscopy with X-ray microanalysis, chemometrics and image analysis,’ Microchemical Journal 95, 298–305. https://doi.org/10.1016/j.microc.2010.01.003.
Jaikishan S, Desai M, Rehren T 2021, ‘A journey of over 200 years: early studies on wootz ingots and new evidence from Konasamudram, India,’ Advances in Archaeomaterials 2(1), 15–23. https://doi.org/10.1016/j.aia.2021.04.002.
Maritan L, Piovesan R, Dal Sasso G, Baklouti S, Casas L, Mazzoli C, Salmoso L, and Corain L 2020, ‘Comparison between different image acquisition methods for grain-size analysis and quantification of ceramic inclusions by digital image processing: how much similar are the results?’ Archaeological and Anthropological Sciences 12, 167. https://doi.org/10.1007/s12520-020-01096-0.
Reedy C, Anderson J, Reedy T, and Liu Y 2014, ‘Image analysis in quantitative particle studies of archaeological ceramic thin sections,’ Advances in Archaeological Practice 2, 252–268. https://doi.org/10.7183/2326-3768.2.4.252.
Rehren T and Hauptmann A 1994, ‘Römische Eisenblöcke von der Saalburg: Untersuchungen zur Fertigungstechnik’ Saalburg-Jahrbuch 47, 79–85.
Scott D A 1991, Metallography and microstructure of ancient and historic metals (Marina del Rey, CA).
Scott D A 2013, Ancient metals: Microstructure and metallurgy Vol IV: Iron and steel (Los Angeles, CA).
Vander Voort G 2015, ‘Introduction to quantitative metallography’, Tech Notes 1(5). https://www.buehler.com/assets/solutions/technotes/vol1_issue5.pdf.
Wayman M L and Juleff G 1999, ‘Crucible steelmaking in Sri Lanka,’ Historical Metallurgy 33(1), 26–42.
How to Cite
Estimating carbon content in crucible steel using image analysis. (2023). Historical Metallurgy, 54(2), 54-64. https://doi.org/10.54841/hm.664
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Articles