Subsequent Yield Surfaces for Annealed Mild Steel Under Dead-Weight Loading: Aging, Normality, Convexity, Corners, Bauschinger, and Cross Effects

After initial yielding of one to five percent small-offset multiple-probe yield curves were determined under combined axial-torsion loading for six tubular specimens. Subsequent yield curves were obtained following either strain aging or loading into the plastic range. Aging and plastic straining usually resulted in smooth, convex yield curves. Occasionally well-rounded blunt corners were formed under combined tension and torsion. Subsequent curves underwent translation and changes in shape. Plastic strain increment vectors from zigzag loadings supported well-rounded blunt (not sharp) corners. Normality of plastic strain increment vectors was observed.