Measurement and prediction of plastic anisotropy in deep-drawing steels

Abstract

R-values and yield stresses were measured as a function of inclination with respect to the rolling direction on 15 steels selected from four basic types [high-strength low-alloy (HSLA), Al-killed drawing quality (AKDQ), interstitial-free (IF), and rimmed]. Orientation distribution functions (ODF’s) were also determined for these steels, using both X-ray and neutron diffraction techniques. The series expansion method was employed for predicting the plastic anisotropy of the rolled sheets. Comparison with the experimental measurements indicates that the “pancake” relaxed constraint model is a more accurate predictor of behavior than the Taylor, Sachs-Kochendorfer, or two other relaxed constraint models. The best quantitative agreement is obtained when the critical resolved shear stress (CRSS) ratio for glide on the {112} (111) and {110} (111) slip systems (t112/t110) is 0.95. A “lath” relaxed constraint model (with έ23 relaxed), associated with the same CRSS ratio, leads to good results for steels with elongated microstructures.