Metallic Materials and their Specific Problems for Ultrasonic Testing
The Table of the sound velocities for different steels, published in the 3rd edition of this book, page 527, shows differences of less than 5% for different states of working and for the various alloying metals no systematic influence can be recognized. The processing conditions such as heat treatment, hardening, quenching and cold working have a larger influence than the alloying elements. In general both longitudinal and transverse velocities as well as the attenuation decrease as a result of such processes. The deviations from the value 5.93 km/s for most practical applications can be neglected, but not if precise wall-thickness measurements are to be made. Care must also be taken when using angle probes because a change of only 1% in the transverse wave velocity at a nominal beam angle of 70° causes a change of 1.5°. In critical cases, as for instance at the critical angles for the generation of Rayleigh or creeping waves, velocity changes must be taken into account, and in these cases the decrease of the velocity with temperature also plays a role [437, 1162, 450].
KeywordsZinc Titanium Porosity Nickel Anisotropy
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