INTERNAL ELASTIC STRAINS IN AN IF STEEL FOLLOWING CHANGES IN STRAIN PATH

Residual elastic strains present in an IF steel following rolling and subsequent tensile deformation have been evaluated using X-ray diffrac tion. It was possible to decompose diffraction profiles into two symme trical components notionally corresponding to dislocation walls and ce ll interiors and so estimate the volume fractions and mean elastic str ains associated with these components of the microstructure following different deformation modes. The residual long range elastic strains w ere very small following rolling, but they were much greater following subsequent tensile elongation to macroscopic yield. The mean strains could only account for about one-third of the strain induced anisotrop y of dow stress. It is concluded that insufficient dislocations accumu late at cell walls at macroscopic yield following a path change to giv e homogeneous loading of the dislocation walls, and that this effect c an account for the difference between the macroscopic mechanical behav iour and predictions from the X-ray strain measurements. Copyright (C) 1996 Acta Metallurgica Inc.