The variation of plastic anisotropy during straining

The relationship between length and width strain during a tensile test has been studied in detail for a wide range of low carbon steels. The data have been analyzed in terms of the conventionalr-value,r _e, the instantaneous r-value, r_i, and a linear regressionr-value,r _r. r_r is derived from a linear regression between width strain and length strain, as first suggested by Liu, using data obtained between yield and uniform elongation.r _r was found to be the most suitable method of characterizing the average anisotropic behavior, because its value is unaffected by the presence or absence of inhomogeneous yielding. There are reproducible variations of width strain from linear behavior which are not due to experimental error. These causer _e to vary with strain. No systematic increase or decrease ofr _e with strain was observed, in contrast to previous reports in the literature.