Did the First Iron Blacksmiths Learn to Carburize Iron? Part I: Can Iron be Carburized in a Charcoal-Fired Furnace?

• Published in: JOM (1989) Vol. 68; no. 8; pp. 2250 - 2255
• Main Authors: Verhoeven, J. D., Pendray, A. H., Dauksch, W. E.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.08.2016; Springer Nature B.V
• Subjects: Bars; Carbon dioxide; Carburizing; Charcoal; Chemistry/Food Science; Earth Sciences; Engineering; Environment; Experiments; Fires; Hardness testing; Heat; Historical metallurgy; Iron; Iron compounds; Metal workers; Physics; Steel; Studies; Temperature; Thermocouples; Tuyeres; Wrought iron; Ferrite; Slag Inclusion; Burning Charcoal; Charcoal; Case Depth
• ISSN: 1047-4838; 1543-1851
• DOI: 10.1007/s11837-016-1997-8

There is debate in the literature on whether or not iron can be carburized by simply inserting an iron bar into a charcoal fire. Experiments are presented here in which wrought iron bars have been held in a cylindrical enclosure filled with burning charcoal produced by air flowing up from tuyeres at the bottom with the bottom end of the bars held in the 900°C–1050°C range for 30 min. The bars carburized to a remarkable extent. Martensite case depths on a water-quenched bar were measured ranging from 0.75 mm at the hot bottom end and dropping to 0.02 mm at a distance of 295 mm (11.6 inches) up the bar. The surface of the bar was file hard over this length with measured surface hardnesses in the 60–65 Rc range.