Metallurgical and micromechanical examinations of wear damage after impact-sliding tests on 304L/304L specimen

The control-rod cluster assemblies (RCCAs) can be damaged by impact-sliding wear due to flow induced vibrations which generate contacts with their guidance devices (RCC guide tube). Impact/sliding wear tests have been performed on stainless steel claddings (304L). Only the duration variable has been selected to evaluate the wear effect on the material. Other experimental conditions have been fixed for all tests. Some non-destructive examinations have been performed on the worn specimens, using weighing, scanning electron microscopy and 2-D profilometry. The results show clearly a sensitive damage of the two first bodies. X-ray diffraction measurements have been made in order to evaluate the evolution of the initial microstructure and micromechanical state of the 304 stainless steel (strain hardening, residual stresses and phase transformation induced by plasticity). The use of these techniques show that test duration has no effect on the behavior of material even if wear damage continues to progress. So these data brought us to the fore that the main wear mechanism is an oxidation of the surface layers followed by an oxides detachment stage due to the impact-sliding motion.