Abstract
Residual stresses induced in commercially pure iron specimens by uniaxial tensile or compressive deformation are determined by the X-ray diffraction method. The main results obtained are as follows. The axial residual stress induced by tension is approximately in equilibrium over the cross section of a specimen if measured with respect to {211} diffraction planes. On the other hand, if measurements are made with respect to {220} planes, the residual stress distribution does not satisfy the macroscopic equilibrium giving a tensile “Base Line Stress”. A large compressive base line stress is obtained if measurements are made with respect to {310} planes. The residual stresses induced by uniaxial tension and those by compression are distributed nearly symmetrically over the cross section of a specimen.
In a previous paper, the base line stress measured on a polycrystalline aluminium was theoretically interpreted on the basis of the elastic and the plastic anisotropy of the constituent crystals and the selective nature of the X-ray diffraction method. In the present paper, residual lattice strains induced in a polycrystalline silicon iron specimen are first studied theoretically in a way similar to the case for a polycrystalline aluminium. On the basis of the results obtained for silicon iron, the theoretical analysis of α-iron which has three kinds of slip planes is carried out. As for the magnitude and the sign of the base line stress, there is good agreement between the theoretical and the experimental results on these polycrystalline metals.
