History of Technology in India, Vol. I: From Antiquity to c. 1200 A.D. v1.c13.s2.t11.3

v1.c13.s2.t11.3

So far as the availability of tin ore in India is concerned only very lean ore (Casseterite) is found in Chota Nagpur (M.P.) where the tribal craftsmen of Bastar area are still engaged in producing bronze metal and its castings using the age old lost wax process. The popularity and the massivity of the use of bronze alloys suggest that either the ore or metallic tin was brought from Burma or Malaya with which India had very close trade relations. The cast bronze weapons have very hard but brittle nature and these cannot be generally hot or cold worked. The edge of the cast weapon was sharpened by grinding and no heat-treatment was given because the general hardening treatment viz. solutionizing at high temperature and quenching will decrease the hardness due to the increase in the amount of retained solid solution. In order to increase the hardness, solutionizing treatment has to be followed by precipitation hardening and the metallographic studies of bronze objects have not revealed use of such knowledge.