History of Technology in India, Vol. I: From Antiquity to c. 1200 A.D. v1.c13.s2.t4.124

v1.c13.s2.t4.124

Based on the characteristic features of the fractured surfaces and other properties such as ductility, magnetism and hardness etc. these have been further classified into sub-groups as shown in Fig.32. This type of classification has no parallel in the world. Samuel(1980) writes that for the first time it was only in 1772 that ‘Reamnur’ distinguished between grey, white and mottled cast iron fractures. From the study of the classification of iron-carbon alloy, it is obvious that in India iron technology was much advanced and the ancient craftsmen were capable of selective use of various grades of this alloy. Fig. 33 shows the solid state of the modern iron-carbon equilibrium phase diagram and the hatched band shows the range of iron-carbon alloys produced by the ancient Indians. It is very clear that these alloys were either soft iron (range X) containing little pearlite in the matrix of ferrite (low C steel 0.1 to 0.4% C), or (range Y) high carbon steel (0.7 to 1.5% C) containing cementite in a matrix of pearlite. In some steels the carbon content was found to be as high as 1.9%. It is also very clear that various categories of the iron-carbon alloy