Iron in Ancient India c7.s3: Micrographic Examination of Ancient Ceylon Iron
Iron in Ancient India c7.s3
- Language
- English
Micrographic Examination of Ancient Ceylon Iron
c7.s3.1
The author is not aware of my micrographic examination of the iron of the Delhi pillar or any other specimen of ancient Indian iron. The results of micrographic examination of the three specimens of Ceylon iron by Sir Robert Hadfield will prove interesting. For photographs of micro-sections the reader is referred to Hadfield's paper. We give below only the results obtained by him with respect to the iron chisel, nail and bill-hook, analyses of which have already been given.
c7.s3.2
*Iron chisel*: The transverse section shows that the chisel has been carburised, the section showing the carburised areas to be on two sides. The carburisation varies on two faces from saturation point (‘9 per cent) to about ‘2 per cent certain on the outside edge and the depth of carburisation from the edge inwards is also shown to be variable. The presence of matensite and hardenite suggest the important information that the chisel has been quenched. Further micro-sections were prepared from the specimen cut from the nose of the chisel. These photo-micrographs also appear to carry evidence that the chisel has been quenched for the structure is in parts martensitic. Troostite is certainly also present, which is probably the result of tempering by the long lapse of time. Hadfield believes that for the first time there has been put 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.
c7.s3.3
*Iron nail*: The microstructures indicate a remarkable conglomeration. One plate shows a weld running diagonally across the section, and along the edges of the weld there are carburised areas. Another notable point is that on one side of the weld the slag shows the effect of the forging, whereas on the other side there is no such sign. The specimen is covered with slip bands and has evidently undergone severe hammering, probably in its use as a nail. The carbon in the carburised areas exists as granular pearlite.
c7.s3.4
*Iron bill-hook*: The report of the microstructure of the specimen shows that it contains a large amount of slag and appears to represent what would be now termed a somewhat low quality of wrought iron. There seems to be practically no carbon present and therefore no evidence of treatment other than forging can be obtained.