Crucible technique

Crucible steel is steel made by melting iron and other materials in a crucible. Crucible steel was produced in South and Central Asia during the medieval era. Techniques for production of high quality steel were developed by Benjamin Huntsman in England in the 18th century; however, Huntsman's process used iron and steel as raw materials rather than direct conversion from cast iron as in the Bessemer process. The homogeneous crystal structure of this cast steel improved its strength and hardness compared to preceding forms of steel.

Crucible steel is generally attributed to production centres in India and Sri Lanka where it was produced using the so-called "wootz" process, and it is assumed that its appearance in other locations was due to long distance trade. Only recently it has become apparent that places in Central Asia like Merv in Turkmenistan and Akhsiket in Uzbekistan were important centres of production of crucible steel. The Central Asian finds are all from excavations and date from the 8th to 12th centuries AD, while the Indian/Sri Lankan material is as early as 300 BC. In addition, India's iron ore had trace vanadium and other rare earths leading to increased hardenability in Indian crucible steel which was famous throughout the middle east for its ability to retain an edge.

While crucible steel is more attributed to the Middle East in early times, there have been swords discovered in Europe, particularly in Scandinavia. The swords in question have the ambiguous name inlaid into it, Ulfberht. These swords actually date to a 200-year period from the 9th century to the early 11th century. It is speculated by many that the process of making the blades originated in the Middle East and subsequently been traded during the Volga Trade Route days.

In the first centuries of the Islamic period, there appear some scientific studies on swords and steel. The best known of these are by Jabir ibn Hayyan 8th century, al-Kindi 9th century, Al-Biruni in the early 11th century, al-Tarsusi in the late 12th century, and Fakhr-i-Mudabbir 13th century. Any of these contains far more information about Indian and damascene steels than appears in the entire surviving literature of classical Greece and Rome.

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