History of Technology in India, Vol. I: From Antiquity to c. 1200 A.D. v1.c13.s4.27

v1.c13.s4.27

In order to appreciate the knowledge of the ancient smiths it is essential that we make reference to the Fe-C diagram shown in *Fig. 56*. This figure shows the change in structure of five different Fe-C alloys as attained after normal cooling. This diagram also shows various temperature ranges to which the Fe-C alloy should be heated to carry out different thermomechanical treatment like forging, forge welding, annealing and spherodizing etc. The ancient blacksmiths were ignorant about such phase diagram but they had gained knowledge by experience and they understood the effect of carbon on properties of iron as depicted by the classification and proved by the manufacture of many massive iron objects which have no parallel in the world.