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This work was aimed at explaining the corrosion mechanism of commercial Cr-Mn steels at 1073, 1173 and 1273 K in the atmospheres containing oxygen and sulfur. Three steels were selected for the investigations, two singlephase austenitic steels (Cr17Mn17 and Cr13Mn19SiCa) and a two-phase austenitic-ferritic steel Cr15Mn19. On all studied steels triplex scales were formed. The inner very thin, fine-grained part of the scale contained manganese, chromium and iron sulfides and oxides, the intermediate layer was built mainly of the MnCr 2 O 4 spinel while MnO was the predominant constituent of the outer scale layer. According to the gravimetric measurements, after an initial incubation period, the oxidation of steel follows a parabolic rate law. Thermodynamic and kinetic aspects of the formation of oxide-sulfide and oxide layers were discussed. Oxidation was accompanied by depletion of the subscale region of the metallic core in manganese, which is the austenite former. Consequently austenite transformed into ferrite.

The problems discussed in the present paper are well-known both from the theoretical (numerical) and experimental point of view. The novelty of our approach depends on the application of hybrid experimental methods and a comparison of their effectiveness in the description of complicated fatigue problems arising in the analysis of the behavior of laminated panels with open holes and subjected to tensile loading. Three experimental methods were used: infrared thermography (passive), structural health monitoring (active), and digital image correlation. The experimental investigations were supplemented by the finite element description of the problem dealing mainly with the static behavior, monitoring the development and final fracture of composites. The considerations concern laminated panels oriented at ±45 • with different types of holes, i.e., vertical elliptical, horizontal elliptical, and circular.

In this paper the dynamic behavior of composite multilayered cylindrical panel with a single, square, interlaminar delamination is considered with using finite element method. Based on numerical results it is possible to determine the effect of the delamination on the guided wave propagation in curved structures. The results are used to quantify the difference of response signal in the case of perfect and defected structures. The results indicates that the size and orientations of the defect have a significant influence on overall dynamic behavior and they should be taken into account to design appropriate and effective non-destructive damage test methods and algorithms.

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