From Wrought Iron to Steel

Steel is iron that has carbon fused into the structure of the metal. Carbon contents vary from 0.002% carbon to 2.1% carbon. The amount of carbon in steel varies its hardness, strength and ability to be heat treated. High carbon steel with carbon content of over 0.4% has the ability to be heat treated and hardened, this is very important as it means the steel can be used to make blades that will resist wear aswell as providing a better material to make tools such as hammers and files from.
As talked about before in a previous post Wootz steel was some of the first steel ever to be produced it was known as seric iron. It was produced in bloomeries and furnaces, in Sri Lanka these furnaces used wind power to fuel the furnace with oxygen. Impurities in the iron created a strong, resiliant material called steel. One of the main impurities was of course carbon. Wootz steel was also produced in crucibles that were heated to extremely high temperates, in these crucibles iron and carbon were placed which fused together to create steel. Plants were often used as carbon sources. 
It took along time however for these technological advancements to spread across the globe. Steel production in Eorope began alot later than in Asia however great advancements were made in Europe to the steel production industry. During the middle ages steel was produced in bloomeries and in crucibles using charcoal as the primary fuel source. In 1885 Henry Bessemer invented the Bessemer process which meant the production of mild steel was extremely cheap. This began a number of changes to the steelindustry that made steel production what it is today. Before this case hardening, a method where the outside layer of iron or mild steel is hardened leaving the centre unhardened was used along with a cementation method which produced blister steel. As you can see although it took a long time for steel production to spread across the earth some areas affected later in the developement process of steel production contributed greatly to the industry.



How Iron was Smelted.

Iron was first smelted in bloomeries which are large clay furnaces that use bellows to force air through the furnace. This allows more oxygen to get at the fuel increasing the temperate of the furnace. However the temperature was still not hot enough to melt the metallic iron created from the iron oxides and it collected at the bottom of the bloomery in a bloom. This bloom was then beaten and folded multiple times to form wrought iron. Wrought iron is not very strong compared to bronze however it was widely used and the bronze age gave way to the iron age. Iron ore was more plentiful then the copper and tin which was needed to make bronze which meant it became more popular. Iron was also easier to process into billets of useable metal as bronze is an alloy which had to be made from already processed copper and tin.




The video below gives a good insight into how iron was smelted using old techniques, wooden logs were used as anvils and tools would have been made from wood and other metals such as bronze. 

The origins of smelting Iron.

The exact area where smelting of iron first took place is uncertain as the archaeological remains of smelted iron is hard to distinguish from meteoritic iron which was used before smelting was first invented. Meteoritic iron was often cold hammered into tools and weapons before wrought iron was invented. Meteoritic iron was extremely expensive and was bartered and trade at extremely high costs. Iron smelting, extracting iron metal oxides from ore, is much harder to do then smelting copper and tin as it requires much higher temperatures which are hard to achieve with a solid fuel furnace or kiln. It was first practiced in the Middle East and sub Saharan Africa through to India.

One of the best known types of steel first used that was used around the 6th century BC and onwards, this type of crucible steel is called Wootz steel and originated in southern India. It was renowned all over the world for its edge retention abilities and strength. It was mainly used for sword blades, knives and daggers. Its pattern is iconic and is known as the familiar pattern of Damascus steel. Wootz steel was introduced to Damascus by people from Arabia, Damascus then developed a large trade in making weapons from this steel. That is the reason that the steel is commonly known nowadays as Damascus steel. However most blades made nowadays claiming to be Damascus steel are simply pattern welded steel made of layers of high and low carbon steel, these blades are not real Damascus steel as they do not use real Wootz steel or true Damascus steel however, the properties of modern pattern welded steel are very good for blades of all sorts.

     Introduction

Hi I'm Ben, this is my blog about how Iron was mined, prepared, smelted and used during the Iron Age. I hope to discuss where iron smelting originated, how it was achieved and what impact it had on technology at that time.