In this work, samples have been selected from a large number of pins fabricated and in which varying grain sizes ranging from ASTM 1 to ASTM 6 have been identified by microstructural analysis. Ultrasonic attenuation studies have been carried out on them using 1.25 MHz and 2.5 MHz test frequency.

The test results showed that the variations of attenuation with 1.25 MHz were not significant over the grain sizes considered. On the other hand, with 2.5 MHz as the test frequency significant attenuation was observed for grain sizes of ASTM 1 or above, but very small attenuations over the grain size range of ASTM 4 to 6 which was the predominant grain sizes encountered in the pins. It was also found that the grain sizes remaining the same, the carbide precipitation did not affect the attenuation indicating their non-participation in the scattering processes at the grain boundaries.

The attenuation method as discussed here is being used as a quality control method for 100% inspection of the steel pins used in the Indian Railways.