Nondestructive ultrasonic evaluation of formability of metallic sheets

An indication of the formability of metallic sheet is determined using a correlation between nondestructively measurable ultrasonic properties and a formability index. A calibration relation is initially established by measuring ultrasonic velocities at various angles to the rolling direction of sheet specimens with noncontacting electromagnetic acoustic transducers, calculating an ultrasonic correlation parameter from the measurements, destroying the specimens in tensile tests to measure a formability index, and then correlating the ultrasonic correlation parameter with the formability index. Once this relationship is established, the formability index of a working sample, which is not to be destroyed, is found by making the same types of ultrasonic property measurements on the working sample, calculating the ultrasonic correlation parameter for the working sample, and then employing the previously established correlation to ascertain the formability index for the working sample.