RESIDUAL STRESS INVESTIGATIONS IN AUSTENITIC STEEL SAMPLES WITH DIFFERENT DEGREE OF LOW CYCLE FATIGUE

Abstract

Austenitic stainless steels are widely used because of their high corrosion resistance and toughness. The influence of the applied cyclic load on the mechanical properties of the material is of great current interest. In order to investigate residual stress evolution a series of the austenitic steel samples (X6CrNiTi1810) with different degrees of low cycle fatigue was studied. Martensitic phase formation was observed at different degrees of low cycle fatigue. Residual stresses, microstresses in both phases, as well as martensitic precipitation volume fractions, were estimated. Usually after plastic deformation the martensite phase produces a structure of oriented plates or laths. Therefore martensite texture formation during phase transition can be expected. Indeed the registered neutron diffraction spectra from austenitic fatigued samples show texture presence and its variation in dependence of the fatigue degree. The attempt to consider the texture evolution in dependence of fatigue degree and its influence on the residual stresses was made.