Electron backscattering diffraction analysis of an ancient wootz steel blade from central India

The electron backscattering diffraction technique was used to analyse the nature of carbides present in an ancient wootz steel blade. Bulky carbides, pro-eutectoid carbide along the prior austenite grain boundaries and fine spheroidized carbides were detected. Electron backscattering diffraction was employed to understand the texture of these carbides. The orientations of the cementite frequently occur in clusters, which points to a common origin of the members of the cluster. For the bands of coarse cementite, the origin is probably large coarse particles formed during the original cooling of the wootz cake. Pearlite formed earlier in the forging process has led to groups of similarly oriented fine cementite particles. The crystallographic texture of the cementite is sharp whereas that of the ferrite is weak. The sharp cementite textures point to the longevity of the coarse cementite throughout the repeated forging steps and to the influence of existing textured cementite on the nucleation of new cementite during cooling.

Correlation between microstructure and phosphorus segregation in a hypereutectoid Wootz steel

The influence of bands rich in phosphorus on the microstructure of hypereutectoid Wootz steel implement is described. Electron probe micro-analysis is combined with optical microscopy. Phosphorus-rich bands are seen to correspond to regions of internal cracking, carbon depletion, and enhanced frequency of spheroidized cementite in place of pearlite. A rationale for the findings is presented in terms of the influence of phosphorus on the Fe–C phase diagram and on the rate of the eutectoid reaction.

Electron backscattering diffraction analysis of a reconstructed wootz damascus steel blade

The historical impact and subsequent fame of wootz weaponry in the ancient world has created interest in what has come to be seen as an advanced material even by modern standards. Ancient wootz artifacts are classed as high carbon (hypereutectoid) crucible steels and are characterised by high strength, hardness and wear resistance, but especially by their attractive surface pattern.

Wootz steel project by electron backscatter diffraction

The data is from an electron backscatter diffraction (EBSD) study of the microstructure of high carbon ‘Wootz’ steel. The objective of the study is to infer an unknown thermomechanical history from observation and analysis of the final microstructure in various ancient artefacts (swords and tools), and then compare the findings with heat treatments of the ancient artefacts and modern attempts at duplication of the structure. Electron backscatter data reveals the orientation relationships between various phases in the material, particularly cementite and ferrite.

Wootz steel project by electron backscatter diffraction

The data is from an electron backscatter diffraction (EBSD) study of the microstructure of high carbon ‘Wootz’ steel. The objective of the study is to infer an unknown thermomechanical history from observation and analysis of the final microstructure in various ancient artefacts (swords and tools), and then compare the findings with heat treatments of the ancient artefacts and modern attempts at duplication of the structure. Electron backscatter data reveals the orientation relationships between various phases in the material, particularly cementite and ferrite. The dataset is randomly structured and organised. The data is automatically generated by an electron backscattered diffraction system attached to a field emission scanning electron microscope. The dataset uses proprietary software (cannot be copied or distributed without complying with licensing agreements): Oxford HKL Channel 5. As the native formats are binary they cannot be read with standard software.

Crucible Steel in South India-Preliminary Investigations on Crucibles from Some Newly Identified Sites

European accounts from the 17th century onwards have referred to the repute and manufacture of “wootz’, a traditional crucible steel made especially in parts of southern India in the former provinces of Golconda, Mysore and Salem. Pliny's Natural History mentions the import of iron and steel from the Seres which have been thought to refer to the ancient southern Indian kingdom of the Cheras. As yet the scale of excavations and surface surveys is too limited to link the literary accounts to archaeometallurgical evidence, although pioneering exploratory investigations have been made by scholars, especially on the pre-industrial production sites of Konasamudram and Gatihosahalli discussed in 18th-19th century European accounts. In 1991–2 during preliminary surveys of ancient base metal mining sites, Srinivasan came across unreported dumps with crucible fragments at Mel-Siruvalur in Tamil Nadu, and Tintini and Machnur in Karnataka and she collected surface specimens from these sites as well as from the known site of Gatihosahalli. She was also given crucible fragments by the Tamil University, Tanjavur, from an excavated megalithic site at Kodumanal, dated to ca 2nd c. Bc, mentioned in Tamil Sangam literature (ca 3rd c. BC-3rd c. AD), and very near Karur, the ancient capital of the Sangam Cheras. Analyses of crucible fragments from the surface collection at Mel-Siruvalur showed several iron prills with a uniform pearlitic structure of high-carbon hypereutectoid steel (∼1–1.5% C) suggesting that the end product was uniformly a high-carbon steel of a structure consistent with those of high-carbon steels used successfully to experimentally replicate the watered steel patterns on ‘Damascus’ swords. Investigations indicate that the process was of carburisation of molten low carbon iron (m.p. 1400° C) in crucibles packed with carbonaceous matter. The fabric of crucibles from all the above mentioned sites appears similar. Preliminary investigations on these crucibles are thus reported to establish their relationship to crucible production of carbon steel and to thereby extend the known horizons of this technology further.