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Weight-Related Presentation of Hurst Correlation As a Basis For A Multiscale Distribution Inhomogeneity Evaluation

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Inhomogeneity of the microscopic structure constitutes one of the most important issues in a comprehensive assessment of constructional materials’ structures. The significance of the microstructural evaluation ensues from the fact that this property affects materials’ behavior under load, by controlling the course of decohesion phenomena [1-3] characterized by a multiscale range. [...]

Analysis of inhomogeneity of gradient percolation structures, based on the notion of affinity

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The paper presents the results of an inhomogeneity analysis of gradient percolation structures of cast-iron rollers cast into metal moulds. The variable intensity of cast iron solidification in permanent mould contributes to the creation of a structure of large inhomogeneity degree, characterised with gradients of surface fraction of cementite as well as pearlite and graphite being reversely [...]

A method for evaluation of the size of a grain on non-planar surfaces

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In the stereological methods [1÷3], applied to describe the grain size of polycrystalline materials, images of metallographic specimens or images of plane sections of three-dimensional model structures are used. Frequently, it becomes necessary to evaluate the grain size in finished components, for which, due to their manufacturing technology, it is impossible to make microsections without destroying the component. In such cases, the possibility to evaluate the size of grain on a non-planar surface would be an effective solution. However, the reference publications do not provide any information in this respect, while there is an urgent need for such, i.e. study in order to improve the quality control of many parts, including turbine blades produced by investment casting. PHASES OF EVALUATION OF THE GRAIN SIZE ON A NON-PLANAR SURFACE Evaluation of the grain size on a non-planar surface is a multiphase task. In the first place, the grain boundaries must be detected. This is combined with photographic documentation, including an image of orthogonal projection of a non-planar surface. Based on the image of the projection, a quantitative analysis of the structure is performed in order to determine the necessary stereological parameters and coordinates of grain boundaries points. The values of stereological parameters obtained by measuring serve as reference values for the evaluation of the grain size on a non-planar surface obtained through approximation of geometric measurements of the real surface area of the investigated component. The coordinates of grain boundaries, determined in the orthogonal projection image, provide a foundation for mapping the image of the structure on an analytical non-planar surface and for calculating stereological parameters. A detailed discussion of the particular phases of evaluation of the grain size on a non-planar surface was based on an example of a test component presented in Figure 1. The su[...]

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