Experimental aluminum alloys with the addition of iron, which model the materials obtained with the addition of recyclables, were investigated. The use of the recyclable (silumin waste, production waste, remelting of canned scrap, etc.) seems to be promising for the national economy. In the work, the alloy of the Al-6 % Sn-5 % Si-4 % Cu (mass. %) system was used as a base, to which iron (1 %) and other elements (bismuth, lead, manganese) were added. The samples under investigation were subjected to heating up to 500°C and cooling in various regimes. It was shown that the best results were achieved with cooling in water: the phases were spheroidized and properties were improved. Complex method of microscopy, including optical, electronic (with X-ray spectral microanalysis), and probe microscopy was used, in order to study alloys before and after tribological tests. An investigation of the initial structure of the samples showed that the combined addition of iron with manganese (0.5 %) led to the formation of favorable skeletal phases. The tribological tests without lubrication which modeled the extreme conditions of operation were carried out. These experiments showed that the investigated alloy had an increased wear resistance, which could be associated with the formation of skeletal phases. After tribological tests, significant changes in the structure and phase components at the surface and in the near-surface layer were observed. For the study of this layer, an oblique cut was made, on which near-surface area with a thickness of 50-100 μm was detected.

In the paper there is presented a procedure for the life testing of a hinge pivot in a dump car. This unit is one of the most significant elements in the design on which depends traffic safety. As a method for the estimate of reliability and life of the element under consideration there are chosen accelerated life tests allowing the definition of fatigue strength characteristics using a limited number of samples at the specified forced mode. Particular attention is paid to the circuit of sample installation on a plant, to the circuit of loading, to the estimate and substantiation of load values at the known loading range of the hinge pivot unit corresponding to speed motion distribution of a car under operation. The analysis of acting loads in operation is carried out, a total damaging impact during car operation and an equivalent force of sample loading are defined identical by a damaging impact to an acting loading range of a sample under testing are defined. According to the investigation results there is developed and approbated successfully a new procedure for the fulfillment of bench tests allowing more complete and reliable estimates of hinge pivot unit life for a dump car in comparison with computational methods.

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