Key Engineering Materials Vol. 635

Abstract: Deformation characteristics are analyzed for stress components deformation zones to move and bend. To verify the appropriateness of the proposed model were experimentally determined strength and deformation characteristics of deep-drawing steel DX 57 D, microalloyed steel HSLA , high-strength multi-phase steels DP 600 and TRIP, anti-corrosive austenitic steels A304 2B and ferritic A 430 2B by three-point bending. The analysis of the results obtained Cause and Effect matrix shows that for front impact deformation zones are more suitable austenitic steels respectively TWIP and for zones flanking the passenger compartment (cab) are preferable DP and TRIP steels.

Abstract: The paper deals with the determination of corrosion rate to the natural gas pipeline API 5L X60 in Trnava region. Linear polarisation resistance method (exposure time 1 hour) was used for investigation the corrosion rate of exposed samples in the environment (top, middle and lower part of soil excavation and distilled water). The corrosion rate was also determined by measuring the weight loss of the steel samples. The exposure time for the measurement method of the weight loss of metallic materials accounted 120, 288, 528 hours. These outputs helped to identify the most suitable environment for the tested metallic material. Top and middle part of soil excavation was situated in the least aggressive environment. On the other hand, the lower part of soil excavation was situated in the most aggressive environment for API 5L X60.

Abstract: The contribution deals with the evaluation of wear blades continuous blasting machine. The current state of wear of blades and a description of the blasting process is analyzed. In the experimental part of this work the quality of the blades is evaluated by measuring the hardness of materials, chemical analysis of the samples and their structural analysis. Abrasive wear was evaluated in loose fill abrasive and in the environment with firmly bonded abrasives. The results of the measurements showed that the material of the blades is hypoeutectic white cast iron with different carbon and alloying, especially Chromium.

Abstract: This contribution deals about study of mechanical properties and compatibility between PA6 polymer as matrix and modified and unmodified montmorillonite clay nanofiller Cloisite. For this purposes in the first part of study the Hamaker constants, Adhesion work and B parameter for systems PA6/Cloisite 30B, PA6/Cloisite 93A and Pa6/Cloisite Na+ were calculated and compared. The second part of article consists of mechanical tests (tensile test, impact test) of moulded samples and Scanning Electron Microscope (SEM) study of these samples.

Abstract: The durability of concrete structures is an important issue. Eurocode EN 206-1 introduces the k-value concept for concretes made with supplementary cementitious materials; a prescriptive concept that recommends limiting water/cement ratio values for a specified exposure class. A more advanced performance-based concept directly requires that concrete be designed in terms of performance-related parameters, an approach which seems to be more suitable when durability must be achieved. The application of mathematical models in durability assessment is advocated, and an example is shown.

Abstract: In this article we focused to influence of current density on the structure parameters evaluated by microdiffraction experiment in transmission mode using synchrotron radiation. For this purpose the coatings of Ni-Co alloy were deposited on the Cu substrate using different current densities during the electrodeposition process. The results of the microdiffraction experiment showed the structure uniformity of the coatings along their thickness, as well as changes in the structure parameters depending on the used current density during the deposition process.

Abstract: The paper is focused on the study of the material changes which can occur on the basis of mechanical and thermal loading in relation to the functional surfaces of the construction parts. The structural or the mechanical changes can be influenced by ambient environment and in this case, it is the influence of liquid media. The water, hot metal as well as molten glass can be the representatives of the mentioned liquid medium. In relation to the influence of the liquid medium, there is the danger of superposed wears while one of these wears is considered as dominant. Furthermore, occurrence of the corrosion process leads to the increases of the given dominant wear. In relation to the analysis and evaluation of the wear, the simulated tests under the critical conditions are necessary for the correct and precise prediction of the degradation processes. Experimental measurements can be used for the prediction of the material behaviour under the critical operation conditions. In the given work, the attention was paid to the selected materials which were exposed to the mechanical as well as mechanical-thermal loading. The important parameters were achieved with help of the testing device which was modified in a special way. Moreover, the structure changes were observed for the different time intervals or periods. On the basis of the susceptibility to the loading, the conclusions as well as recommendations were summarized for the selected materials.

Abstract: Changes in selected physical properties of thermoplastic composites during and after exposure materials to ultraviolet radiation and freeze were investigated. The matrix of composite was homopolymer polypropylene. The fillers were talcum, chalk, short glass fiber in mass fraction 10 to 50% and montmorillonite by fraction only 4%. The composites were mixed in plasticizing system of extruder. The length of plasticizing system and number of grooves in feed zone was changed. The samples were exposed for two months to UV and -20°C. The short ageing influenced on hardness, microhardness and Raman spectroscopy of composites. The SEM showed how extrusion process affected the homogeneity of composites structure.

Abstract: The macroscopic mechanical properties of steel are highly dependent upon microstructure, morphology, and distribution of each phase present. Nanomechanical testing (Depth sensing indentation) provides a straightforward solution for quantitatively characterizing each of these phases because it is very powerful technique for characterization of materials in small volumes. Measuring the intrinsic properties of each phase separately in multiphase materials gives information that is valuable for the development of new materials and for modelling [1]. In this work, depth sensing indentation has been used to reveal mechanical properties of different phases in steel sheets.