Iron in Ancient India c9.s3.10

c9.s3.10

Steel may be prepared in two ways, firstly, by removing part of the carbon of cast iron before it is converted into wrought iron; or secondly, by carburising wrought iron or making it combine with the requisite quantity of carbon. The second process is called the "process of cementation" and has been discovered in England only in the eighteenth century, while Indian iron was prepared by this process from time immemorial. As has already been mentioned, Sir Robert Hadfield on examining photomicrographically some ancient Ceylonese iron specimens of the fifth century A.D. found that a chisel showed distinct signs of carburisation varying on the two faces "from saturation point (·9 per cent) to about ·2 per cent carbon on the outside edge." He further remarks: "the presence of martensite and hardenite suggests the important information that the chisel has been quenched."¹ Sir Robert concludes: "the author believes this to be the first time there has been put up on record evidence of the art of cementation having been known 1500 to 2000 years ago, as shown by these specimens; probably therefore, such knowledge could be traced back still further." Ceylon, having been only a part of Greater India, we may safely conclude that the process of cementation and quenching was known in India "1500 to 2000 years ago," if not earlier.