INVESTIGATION OF THE DISLOCATION STRUCTURE AND LONG-RANGE INTERNAL STRESSES DEVELOPING IN AN AUSTENITIC STEEL DURING TENSILE TEST AND LOW-CYCLE FATIGUE

Abstract

18/10 austenitic stainless steel samples were tensile deformed to different strain values, and fatigued with different plastic strain amplitudes up to failure. In latter case special care was taken to unload the samples either from the tensile or the compressive stress maximum of the hysteresis loop, respectively. The specimens were cut perpendicular and parallel to the load axis, and these surfaces were investigated by high resolution X-ray line profile analysis. The line profiles reveal characteristically asymmetric line broadening as compared to the undeformed initial state. From the line broadening and the asymmetry the dislocation density and the long-range internal stresses prevailing in the cell walls and in the cell interiors have been evaluated. The long-range internal stresses were interpreter! on the basis of the composite model of the dislocation cell structure. The results can be used for the different residual life prediction methods.