ACOUSTOELASTIC DETERMINATION OF THE HIGHER-ORDER ORIENTATION DISTRIBUTION FUNCTION COEFFICIENTS UP TO 1 = 12 AND THEIR USE FOR THE ONLINE PREDICTION OF R-VALUE

The higher order orientation distribution function (ODF) coefficients up to l = 12 in cold-rolled and annealed sheet steels were evaluated and calculated nondestructively from the anisotropy of the ultrasonic velocities of the lowest order symmetrical Lamb (S0) and shear horizontal (SH 0) waves propagating in the rolling plane. The elastic energy method was employed, together with a decomposition of the texture into the principal preferred orientations, following a procedure originally developed for Young's modulus data obtained destructively. Plastic strain ratios are estimated using the series expansion method, in conjunction with a relaxed constraint (pancake) grain interaction model. The r- value predictions based on the ODF coefficients obtained in this study are compared with tensile data and with empirical predictions made using the Modul-r approach. © 1990 The Metallurgical of Society of AIME.