PSI - Issue 43

Pavel Doubek et al. / Procedia Structural Integrity 43 (2023) 101–106 Pavel Doubek et al./ Structural Integrity Procedia 00 (2022) 000 – 000

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The declared and real chemical compositions of the materials Metco 51NS and Rockit 401 are solved profoundly in the article by Doubek et al. (2022, under review) to which this text refers , see also Höganas (2022) , Oerlikon Metco (2022) and Hardchrome Engineering (2021). The samples used in the microhardness tests had dimensions of 5.5 × 21 × 100 mm. The total thicknesses of the cladded layers (applied in two or three layers) were between 1 and 2 mm after machining, see Fig. 3.

(a)

(b) Fig. 3. Applied specimens composed of steel substrate coated with; (a) an aluminum bronze layer, and (b) a hard chrome layer. The change of the fracture-mechanical properties of a new laser-cladded layer on the existing material was tested by microhardness according to Vickers, see e.g. Tabor (1951). During the measuring of hardness, the indenter is pressed into the surface of the tested material with a predefined test force. After unloading, the size of the impression is measured, see Fig. 4. The material hardness is then calculated as a ratio of the test force [kgf] and the real impression area . The Vickers hardness is calculated from the mean of the impression ’ s diagonals [mm] and the equation (1) = 1.85 4 ∙ 2 (1)

(a) (b) Fig. 4. The Vickers microhardness test; (a) an example of hardness measurement paths via bi-material interface (two sets of microhardness measurements were performed on each sample), and (b) the phases which have a fundamental influence on the course of microhardness. Young ’ s modulus of elasticity is determined from the indentation diagram, which describes the dependence between the force acting on the indenter, and the indentation depth in the measured material. In this study, the constant loading force was applied to determine the approximate values of Young ’ s modulus. The results were calibrated against the Young ’ s modulus of the substrate known from the previous experimental campaign, and Young ’ s modulus of the cladded layer known from material datasheets.