Help Desk -
9958816305, 9810335381

Chromium Crucible Steel was First Made in Persia 900 Years Ago

Steel News - Published on Wed, 23 Sep 2020

Image Source: Chromium Crucible Steel Persia
For more than a century, evidence for the production of crucible steel in Central and Southern Asia, prior to the European Industrial Revolution, has fascinated and challenged material scientists, historians and archaeologists. At the same time, chromium-alloyed stainless steel was developed in the early 20th century, building upon 19th century experiments with low chromium steel. Now, however, academics have revealed that medieval Persians were using the element in steel alloys to give their weapons a cutting edge almost a millennium before the likes of Harry Brearley, the metallurgist behind stainless steel.

A team led by Dr Rahil Alipour, of the Institute of Archaeology at University College London, studied metal particles from the steelmaking centre of Chahak, in Fars province, southern Iran. The particles were dateable from their context to the 11th-12th centuries. They discovered that the steel which was produced there in small crucibles contained a consistent chromium content of about 1 per cent.

Dr Rahil Alipour said: "Our research provides the first evidence of the deliberate addition of a chromium mineral within steel production. We believe this was a Persian phenomenon. This research not only delivers the earliest known evidence for the production of chromium steel dating back as early as the 11th century CE, but also provides a chemical tracer that could aid the identification of crucible steel artefacts in museums or archaeological collections back to their origin in Chahak, or the Chahak tradition."

A contemporaneous crucible steel flint striker held in the Tanavoli Collection is reported to also contain chromium, suggesting its origin from Chahak. The mysterious compound rusakhtaj from Biruni's recipe for crucible steel making refers to the mineral chromite. Additional historical sources up to the mid-2nd millennium CE refer to crucible steel from Chahak as being particularly brittle, consistent with its increased phosphorus content.

Chahak is described in a number of historical manuscripts dating from the 12th to 19th century as a once famous steel production centre, and is the only known archaeological site within Iran's borders with evidence of crucible steel making. The manuscript al-Jamahir fi Marifah al-Jawahir, A Compendium to Know the Gems, 10th-11th CE, written by the Persian polymath Abu-Rayhan Biruni, was of particular importance to the researchers given it provided the only known crucible steel making recipe. This recipe recorded a mysterious ingredient that they identified as chromite mineral for the production of chromium crucible steel. While Chahak is registered as a site of archaeological importance, the exact location of crucible steel production in Iran remained a mystery and difficult to locate today, given numerous villages in Iran are named Chahak.

The team used radiocarbon dating of a number of charcoal pieces retrieved from within a crucible slag and a smithing slag, by-products left over after the metal has been separated, to date the industry to the 11th to 12th century CE. Crucially, analyses using Scanning Electron Microscopy enabled them to identify remains of the ore mineral chromite, which was described in Biruni's manuscript as an essential additive to the process. They also detected 1-2 weight percent of chromium in steel particles preserved in the crucible slags, demonstrating that the chromite ore did form chromium steel alloy

Source :

Posted By : Yogender Pancholi on Wed, 23 Sep 2020
Related News from Steel segment