Characterisation of long term aging behaviour of 9Cr-1Mo ferritic steel using ultrasonic velocity

Abstract

The measurement of ultrasonic velocity of 9Cr-1Mo ferritic steel thermally aged at 793 and 873 K exhibited four distinct regimes in the variation of ultrasonic velocity with aging time. These different regimes have been correlated with the progressive evolution and coarsening of precipitate microstructure studied using TEM and microhardness measurements. The study revealed that ultrasonic velocity can be used to examine the secondary precipitation in the steel and the use of this technique as such can be extended to the health assessment of a component during service.