<p class="AMStitle">Abstract</p><p class="AMSmaintext">The aim of the submitted work is to study the influence of applied loads ranging from 0.09807 N to 0.9807 N on measured values of micro-hardness of heat treated aluminum alloy 6082. The influence of applied load on a measured value of micro-hardness was evaluated by Meyer’s index n, PSR method and by Analysis of Variance (ANOVA). The influence of the load on the measured value of micro-hardness is statistically significant and the relationship between the applied load and micro-hardness manifests the moderate reverse ISE. As the temperature of the solution treatment rises, the YS/UTS ratio and also Meyer’s index n, measured and “true hardness“ increase. On the other hand, its effect on the plastic properties of the alloy is ambiguous.</p>
The welding of alloy steels in practice is a difficult process in order to achieve mechanically or chemically resistant high-quality welds. In some cases, the weldability of many materials can be difficult or is not recommended because of poor and unsuitable properties of welded joints. In our research work, we investigate the selection of an appropriate welding method for welding the manganese steel HS 20 used at dynamically strained components in the car industry. The welding methods have been selected from accessible methods of the KARRER, s.r.o. Tovarníky industrial plant. Based on the comparable welding technologies MMA, MIG/ MAG and TIG, we tested and verified the quality of welds by means of selected weld tests. The quality of these welds, obtained by the abovementioned methods, was evaluated by weld tests in laboratory conditions of the Department of Quality and Engineering Technologies (Slovak University of Agriculture in Nitra) in cooperation with NDB, s.r.o. Bratislava and SES Tlmače, a.s. The aim of the research work is to set the most suitable and effective method of welding for given components from all the technologies available in the mentioned industrial plant. Based on relevant information, we also want to enrich the scope of knowledge about welding of manganese materials in order to make the welding process more effective.
The purpose of the paper was to evaluate the probability of the top event in the fluidity test by Fault Tree Analysis (FTA). One of the important tests used in the foundry practice is the test of the fluidity. Fluidity is the ability of the molten metal to fill the cavity of the molds and create a cast. The AlSi10MgMn (EN 1706) alloy with 5 or 10.54 % of silica was the experimental material. The melted alloy was cast into "horizontal" three-channel mold to test its fluidity. The pouring temperatures were between 605 and 830 °C. In some cases, the experiment was not successful, for a some reasons. This fact led to a waste of time, energy, potential risk of accident, confusion among participants, especially "beginners" founders and became an impulse for the analysis of creation and possible events of fault for the fluidity test using the FTA. It has been found that for the probability of the top event in examined process was disproportionately high (0.29824). The Monte Carlo method was used for the simulation of the effect of decreasing the probability of basic events on the probability of the top event – the fault of the fluidity test.
The aim of the submitted work is to study the relationship between the local deformation and the indentation size effect (ISE). A local value of reduction of the area (Z) was used as the measure of the deformation. Applied loads in the micro-hardness test ranged between 0.09807 to 0.9807 N. The micro-hardness was measured on the cross section in the longitudinal axis of the fractured sample after the uniaxial tension test. The material of the sample was 99.5% aluminium. The influence of both load and deformation on the ISE was evaluated by the analysis of variance (ANOVA). The influence of the load was also evaluated by Meyer’s index n, PSR method, and Hays–Kendall approach. The influence of both factors on the measured value of micro-hardness and therefore on the ISE is statistically significant. The ISE is normal in the areas with high deformation, on the contrary, in areas with low deformation, it has a “reverse” character. The difference between load independent “true hardness” and measured micro-hardness HV0.05 increases with increasing deformation.
The aim of the submitted work is to study the relationship between the local deformation and the Indentation Size Effect (ISE). A local value of reduction of the area (Z) was used as the measure of the deformation. Applied loads in the micro-hardness test ranged between 0.09807 N to 0.9807 N. The micro-hardness was measures on the cross section in the longitudinal axis of the fractured sample after the uniaxial tension test. The material of the sample was 99.5% aluminium. The influence of the load was also evaluated by Meyer's index n, PSR method and Hays therefore on the ISE statistically significant. The ISE is normal in the areas with high deformation, on the contrary, in areas with low deformation it has the "reverse" character. The difference between load independent "tru hardness" and measured micro-hardness HV0.05 increases with increasing deformation
European Union legislation requires organizations to assess their processes in the context of risk management. The main task of risk management is to manage all risks that can significantly affect the outcome of processes. The article is focused on risk evaluation in pressure leaching at elevated temperature using the method Fault Tree Analysis (FTA). The effectivity of pyrite and arsenic pyrite decomposition by oxidative pressure leaching is influenced by the duration of the process, by the temperature, concentration of the leaching solution and by a density of the slurry. It was found that, under equitable conditions, the arsenic pyrite decomposes more intensely than pyrite. Under laboratory conditions, leaching is performed in an autoclave. Due to the aggressive environment, increased pressure and temperature, process failure is possible. Its probability was calculated by FTA. It has been found that the probability of the top event in the examined process was disproportionately high (0.057) and represents an invitation to take corrective actions. The Monte Carlo method was used for the simulation of the effect the probability of basic events on the probability of the top event—the failure of the leaching process.
The main mission of the internal quality system in educational institutions is to develop the importance of quality in all processes, create suitable conditions for increasing the loyalty and professional development of faculty staff, continually improve student satisfaction, and achieve recognition of educational institutions in the eyes of the public. In the Introduction, this paper covers the current state of the field of quality assurance of higher education in Slovakia. Quality management models that can be used appropriately and effectively in university conditions are identified in the next section. The aim of this overview section was to summarize the advantages and disadvantages resulting from the implementation of quality management models. The paper also includes a case study in which selected models of quality management implemented at a private university in Slovakia are described, especially the process model ISO 9001 and the common assessment framework (CAF) model. The self-assessment within the CAF model was carried out by a questionnaire survey; the obtained data were assessed by classical CAF scoring. The aim of the self-assessment was to identify problem areas and opportunities for improvement and to propose corrective actions. The specifics of the implementation of quality management models at a private university and the benefits resulting from the application are also been defined at the end of the article.
Deposits of old blast-furnace slag are an environmental problem. The slag’s hardness is an important for calculation of the energy cost for crushing and grinding process. Due to its porosity, measurement of the (macro) hardness is. To adapt the dimensions of the indentations to the character of the slag, it is necessary to apply loads in the range of micro-hardness. The purpose of this paper is to evaluate the influence of load on the micro-hardness - the Indentation Size Effect (ISE) using Meyer’s, Hays-Kendall and PSR methods. ISE for all samples is “normal”, the slag’s basicity affects micro-hardness and ISE.
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