Very Old Pearlite

H. K. D. H. Bhadeshia

The following images have kindly been donated by Professor Juan Antonio Martinez, Dpto. de Ciencia de los Materiales e Ingeniería Metalúgica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Spain, for teaching purposes. Full details are available in Esther Bravo Muñoz, Jorge Chamón Fernández, Javier Guzmán Arasanz, Raquel Arévalo Peces, Antonio Javier Criado, Christian Dietz, Juan Antonio Martínez and Antonio José Criado Portal, Journal of Nuclear Materials 349 (2006) 1-5.

The first three micrographs are from modern hypo- and hyper-eutectoid steels, presented for comparision with ancient pearlite which has aged for centuries and millennia. The ageing presumably is under "ambient" conditions with the samples obtained from archaeological excavations.

Figura_02__
Modern hypoeutectoid steel showing a thin interlamellar spacing in the pearlite after hot-rolling and normalising. Fe-0.2C-0.4Mn wt%.
Figura_03__
A modern hypereutectoid steel, Fe-1.85C-0.03Si-0.11Mn-0.21P-0.15Cr-0.06Ni-0.04Cu wt%, hot-rolled and normalised. Show proeuctectoid cementite and fine pearlite.
Figura_04__
A modern hypereutectoid steel, Fe-1.85C-0.03Si-0.11Mn-0.21P-0.15Cr-0.06Ni-0.04Cu wt%, hot-rolled and normalised. Show proeuctectoid cementite and fine pearlite. Higher magnification image to show the curved layers of cementite.
Figura_05__
Pearlite in a hypoeutectoid steel Roman nail from Cerro Muriano (Cordoba province), dating first century B.C. to 1st century A.D. Shows cementite in the pearlite as prismatic lamellae. The original nail was 12 cm long, from a Roman thermal spring.
Figura_06__
Higher magnification image. Pearlite in a hypoeutectoid steel Roman nail from Cordoba, dating first century B.C. to 1st century A.D. Shows cementite in the pearlite as prismatic lamellae. The original nail was 12 cm long, from a Roman thermal spring. Shows the fragmentation of the lamellae.
Figura_07__
A 5th century A.D. nail from a Roman hermitage in Mijangos (Burgos Province), showing the pearlite in a hypereutectoid steel. The hermitage is late Roman empire and Visigotic period.
Figura_08__
A 5th century A.D. nail from a Roman hermitage in Mijangos (Burgos Province), showing the pearlite in a hypereutectoid steel. Higher magnification image showing the strange pattern of proeutectoid cementite and cementite which used to be in pearlite.
Figura_09__
A 10th century nail from the Great Mosque of Cordoba. There are in the pearlite, entangled prismatic-layers of cementite.
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