1.1 This standard describes the method for ultrasonic testing of ferritic castings of carbon and low alloy steel. This standard is not applicable for austenitic steel castings.
1.2 The metallurgical grain structure has an appreciable effect on ultrasonic transmission and in order to obtain a favourable grain structure, it is desirable to heat-treat the castings before carrying out ultrasonic examination. Ultrasonic examination can be carried out with equal ease on castings which are annealed or normalized or are in hardened and tempered condition.
IS 7666-1975 history
1975IS 7666-1975 Recommended procedure for ultrasonic testing of ferritic castings of carbon and low alloy steels