MATERIALS ENGINEERING, Vol. 17, 2010, No. 4
published on December 2010

CONTENTS and ABSTRACTS

Major, Š. (pp. 1-6)
EFFECTIVNESS OF THE FATIGUE CRITERIA FOR COMBINED BENDING – TORSION LOADING Full text (PDF 173 kB)
Most of mechanical components in the engineering are frequently subjected to combined loading, which can lead to sudden fatigue failure. In present work the fatigue life of plasma-nitrided and virgin specimens is studied. Specimens made of low-alloy high-strength steel. Specimens were subjected to an in-phase combined bending-torsion loading. The plasma-nitrided specimens have significantly improved fatigue resistance. The most relevant goal of this paper is to verify the efficiency of classical and advanced stress based multiaxial criteria. The criterion proposed by McDiarmid was found to be the most precise in the fatigue life prediction for virgin specimens. On the other hand, the Matake criterion was the most successful for nitrided specimens.

Liptáková, T., Fajnor, P., Dodek, A. (pp. 7-13)
EVALUATION OF THE FLOW ACCELERATED CORROSION OF COPPER PIPES Full text (PDF 5724 kB)
Corrosion behavior of the Cu pipe system has been investigated by long term experiment. The two identical experimental systems were made and fulfilled by the solution of 3 % NaCl. The work medium in the first system was flowing eight hour in day and in the second the medium was stagnant. The systems were subjected eight hour in day to temperature of 80°C. After eleven month the experiment was finished and the corrosion attack and character of corrosion products in the systems have been investigated by light and SEM microscopy, EIS tests and visually too.

Hadzima, B., Bukovina, M., Doležal, P. (pp. 14-19)
SHOT PEENING INFLUENCE ON CORROSION RESISTANCE OF AE21 MAGNESIUM ALLOY Full text (PDF 486 kB)
Evaluation of the electrochemical characteristics of the AE21 magnesium alloy is presented in the article. The surfaces of tested alloys were treated by grinding and grinding followed by sodium bicarbonate shot-peening. The specimens were evaluated by electrochemical impedance spectroscopy method in combination with exposure tests in 0.1 NaCl solution. The exposition times were from 5 minutes to 168 hours. The measured data were analysed using equivalent circuits and polarization resistances of the various corrosion systems were determined. Results of the electrochemical measurements are complemented by metallographical evaluation of the tested alloy.

Jurči, P., Hudáková, M. (pp. 20-27)
MICROSTRUCTURE OF BORONIZED PM Cr-V COLD WORK LEDEBURITIC TOOL STEEL Full text (PDF 2765 kB)
The PM Vanadis 6 cold work tool steel has been boronized at various processing parameters, austenitized, quenched and tempered to a core hardness of 700 HV. Microstructure, phase constitution and microhardness of boronized layers were investigated. It was found that the boronized layers are of two-phase FeB/Fe2B constitution, with an addition of small portion of CrB. Below the boronized layer, intermediate region with elevated carbides ratio was developed. Boronized layers contain also carbides, as a result of the fact that they did not undergo dissolution in the austenite during processing. The hardness of compound layers ranged between 1850 and 2100 HV 0.1 for the FeB-region and between 1750 and 1850 HV 0.1 for the Fe2B-region, respectively.

Ulewicz, R., Nový, F., Mazur, M. (pp. 28-32)
THE ROLE OF OBJECTIVE FUNCTION IN ENGINEERING DESING Full text (PDF 803 kB)
The process of material choice is a key element in the production of machines, devices and other engineering constructions. Engineering design relates to the design of engineered artifacts formed by materials of various types. Materials play an important role during the entire design process. At the early design stage, materials may achieve some of the required functions. Therefore, designers may need to identify materials with specific functionalities in order to find feasible design concepts including the costs of material and technology. In this paper, an overview of research in materials identification and materials selection is introduced. The objective function was used in the material selection. The assumed demands in industrial practice were verified by means of criteria patterns.


© University of Žilina, Faculty of Mechanical Engineering, ISSN 1335-0803