Crucible steel

Crucible steel is a term that applies to steel made by two different methods in the modern era, although it has been produced in varying locales throughout history. It is made by melting iron and other materials in a crucible and pouring the molten metal into a mould. 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.

Early history

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.