42 - Nodularity in Coupons

Abstract:

A correlation between nodularity and ultrasonic velocity was developed for test coupons. A large number of samples from seven foundries were procured for this investigation. Test bars were produced at various levels of nodularity ranging from 96% to 33%. The coupons were cooled in various manners, including water quenching immediately after solidification. The results of the study showed that the correlation of UT velocity with nodularity varies greatly with the matrix microstructure. When the matrix microstructure is constant, the correlation is significantly better. The most reliable practice would be one where a constant matrix microstructure is achieved each time.