Roman and Chinese Metalworking

Chinese steel was highly valued in the Roman Empire (which controlled much of the western world between 27 B.C.E. and 476 A..), since Roman workshops could not mass-produce metals with comparable strength and sharpness. Steel is a metal alloy (mixture)manufactured by heating iron ore(raw iron)to high temperatures, then combining the molten(melted) metal with carbon or other strengthening elements. The quality of steel produced by these techniques depends on the sustained temperature of the furnace and the quantity and condition of the added compounds. Good-quality steel is harder than iron and has much greater flexibility and strength.Blades made from steel therefore maintain a sharper edge for a longer time and have a greater resistance to rust than their equivalent in iron.Western civilizations did not have sufficient knowledge of the carbon compounds that need to be added to molten iron to produce reliable steel. Instead, the Romans produced wrought iron (iron with very low carbon content) by first heating iron ore in a furnace (oven) to separate metal from impurities in a process known as smelting. This technique was used throughout the Roman Empire to make tools and bladed weapons. The resultant iron also acquired a trace of strengthening carbon from the charcoal fueling the furnaces.

The situation was different in the Chinese Han Empire(206b.c.e.220a.d., where metalworkers using more advanced furnaces had identified the natural compounds that created better-quality iron during the smelting process. Through continual practice they had refined the measurements needed to ensure that the compounds added to iron ore introduced sufficient carbon to create a reliable quality of steel. The Chinese had developed large enclosed furnaces that included bamboo nozzles (round openings) to produce steady streams of air. This made it easier to keep the fire at a steady heat and control reactions within the furnace. Chinese furnaces also burned compressed coal, which further increased temperatures and reduced fuel costs. This was significant because mass-produced cast iron (iron with carbon content greater than 2 percent)could be transformed into steel by applying blasts of cool air that provided oxygen to the molten metal (the”Hundred Refinings Method”). The Chinese also knew how to turn wrought iron into steel. Blades were wrapped in fruit skins rich in carbon containing a small amount of impurities. These packages were then sealed in clay containers and heated at high temperatures over a sustained period(up to twenty-four hours) until the metal absorbed the necessary carbon and strengthening elements. In China, these techniques were used to mass-manufacture a variety of tools, including knives, hammers, and cooking pots.

This important development allowed the Han regime to mass-manufacture high-quality metal, including armor-piercing weapons. The Han understood that steel manufacturing techniques provided Chinese troops with superior armor and weaponry. Consequently, the regime tried to restrict the spread of this technology to foreign peoples and prevent the export of Chinese steel supplies to neighboring nations. However, there were strong incentives for Chinese merchants to break the embargoes(restrictions)an offer steel at high prices to foreign traders Smuggling became a problem, and the warlike Xiongnu people of Mongolia were able to capture Han metalworkers when they raided Chinese territory. From these prisoners the Xiongnu learned how to produce supplies of their own steel weaponry, which they offered for exchange with other peoples. In this way supplies of superior eastern steel reached the Parthian Empire in Iran.

The superiority of this steel weaponry was demonstrated on the battlefield of Carrhae in 53 B.C.E., when a Roman army encountered Parthians from eastern Iran. The steel-tipped arrows carried by the Parthians easily punched through Roman shields and armor. The early Roman Empire possessed no weapons or armor comparable to that of the Parthians. Consequently, Roman authorities did not fully understand the significance of the metal used by their Iranian rivals. It was assumed that Parthian steel was the product of unique iron ores that could only be found in the distant east, and no initiative was taken to determine how these metals could be produced. This explanation seemed reasonable when the Romans considered how geography and climate provided the distant east with better fabrics more precious stones, and more potent flavorings in the form of spices.?

1.Chinese steel was highly valued in the Roman Empire (which controlled much of the western world between 27 B.C.E. and 476 A..), since Roman workshops could not mass-produce metals with comparable strength and sharpness. Steel is a metal alloy (mixture)manufactured by heating iron ore(raw iron)to high temperatures, then combining the molten(melted) metal with carbon or other strengthening elements. The quality of steel produced by these techniques depends on the sustained temperature of the furnace and the quantity and condition of the added compounds. Good-quality steel is harder than iron and has much greater flexibility and strength.Blades made from steel therefore maintain a sharper edge for a longer time and have a greater resistance to rust than their equivalent in iron.Western civilizations did not have sufficient knowledge of the carbon compounds that need to be added to molten iron to produce reliable steel. Instead, the Romans produced wrought iron (iron with very low carbon content) by first heating iron ore in a furnace (oven) to separate metal from impurities in a process known as smelting. This technique was used throughout the Roman Empire to make tools and bladed weapons. The resultant iron also acquired a trace of strengthening carbon from the charcoal fueling the furnaces.?