Relation between Material Properties and Propagation Velocities of Elastic Waves in Steel Sheets and Plates
1981 Volume 30 Issue 332 Pages 496-502
Details
1981 Volume 30 Issue 332 Pages 496-502
Some of the important mechanical properties of a steel sheet or plate, such as the Lankford value, r, and the separation index, SI, show texture dependency. In this study, these two properties, r and SI, were related to the propagation-velocity of elastic waves in steel, which varies with its texture. SI is defined as the total separation length devided by the fractured surface area at the time when fracture occurs on a specimen in the impact test. Elastic waves were propagated in two modes: perpendicular or parallel to its surface.
The main results obtained are as follows:
(1) For elastic waves propagating perpendicularly to its surface, it was found that the square of the propagation-velocity of longitudinal waves, vL2, was proportional to the averaged Lankford value, r, but decreased linearly with increasing SI. The theoretical considerations made in this study revealed that vL decreased monotonously with an increase in <100> axis-density parallel to the normal direction of the specimen, but increased monotonously with an increase in <111> axis-density parallel to the normal direction. The experimental results reported so far show that the <100> axis-density parallel to the normal direction is proportional to SI, and the <111> axis-density parallel to the normal direction is proportional to r. Thus, the combination of these theoretical and experimental results yield the behaviour obtained in the present experiments.
(2) For elastic waves propagating in parallel with its surface, it was found that the square of the propagation-velocity of surface waves, vS2, was proportional to the Lankford value in the direction parallel to the wave-propagation. Lamb waves may also be used for this kind of measurement because of its similarity to surface waves.
Since the propagation-velocity of elastic waves can be measured continuously while steel is being produced, the on-line evaluation of some mechanical properties such as the Lankford value or the separation index of steel seems possible.
