Iron metallurgy

Many two- and three-component systems have been studied and recorded in detail. The iron-carbon system is one that has attracted much attention and been of great value in iron metallurgy. 

Iron in pure form wrought iron) is not very hard. However, an iron implement or weapon may pick up enou carbon from charcoal to form a surface layer of the iron-carbon alloy we call steel This skin is harder than even the best bronze, and holds a sharper edge longer. It was this discovery of steeling in Hittite territory that was the crucial turning point in iron metallurgy. An army clad in hard iron and armed with hard iron was reasonably sure to defeat another army clad in and armed with bronze. Thus came the Iron Age. 

Since the invention of metal technology several thousand years ago, the prevention of metal corrosion has been a problem of fundamental practical importance. As the noble metals were corrosion resistant under normal conditions, the collection of knowledge of what could be done against corrosion really began with the invention of iron metallurgy by the Celtic tribes 3000 years ago. 

A great authority on iron metallurgy in Sweden (and Europe) was Sven Rinman (Chapter 8, Iron, section 8.7.2). In his Mining and Metallurgical Dictionary (Bergiverks-lexikon) he had described a method to determine whether a specific iron was Hkely to be brittle at about 200°C. This cold brittleness is caused by a high content of phosphorus in the iron. Sefstrom himself described the method in the Transactions ofThe Royal Swedish Academy of Sciences in 1830 ... 

---