International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

The paper focuses on the application of friction stir welding (FSW) technology for welding of unequal materials based on aluminum alloys. Joints were made from AW 5083 and AW 6082 materials using FSW technology at different weld speed values. The joints were analyzed metallographically, the hardness of the materials was tested across the cross section of the joint and the strength of the joint was tested by destructive static tensile test. At the lowest weld speed, the materials were not perfectly mixed, there was a macroscopically visible gap at the joint location, which was reflected in the lack of joint strength. At the medium and highest weld speed values, a joint with mechanical properties comparable to those of the base material was formed. Metallographically, the bond between the materials was free of any internal defects.

The aim of this paper is the investigation of the effect of natural aging on the mechanical, physical and microstructural properties of an EN AW-6060 aluminum alloy. These properties were investigated during different aging treatments. Firstly, the effect of natural aging on properties was investigated, after which the influence of natural aging (room temperature pre-aging) on the artificial aging was studied. The results showed the beneficial effect of natural aging in both sets of experiment. During the natural aging, the hardness increased for around 20 % while electrical conductivity values were slightly higher than in the quenched sample. The hardness of the samples gradually increases up to 25 days of natural aging reaching a plateau state, after which the values of hardness remain the same. Also, room temperature pre-aging had a positive effect on subsequent artificial aging. Samples that were pre-aged for 40 days or more before artificial aging had around a 13 % increase in hardness values compared to the samples that were directly artificially aged. Electrical conductivity had increased by around 1 MS/m in pre-aged samples compared to only artificially aged samples. Optical microscopy investigations confirmed the existence of precipitated phases and their distribution in the microstructure.

This work is focused on investigation of different thermomechanical treatment (TMT) regimes influencing mechanical and electrical properties of Al-Mg-Si alloy. Three TMT regimes were chosen, which differ in the number of treatment steps. Grain size, microhardness, electrical conductivity were measured. It was revealed that dividing TMT into 2 stages favorably affects formation of mechanical and electrical properties in Al6101.

At present time there is considerable interest in extending the application area of low-alloy and rather inexpensive heat- hardenable aluminum Al-Mg-Si alloys in the automotive industry, aviation, construction and electrical engineering. In this regard, the topical problem is to enhance strength and electrical conductivity of such materials, which would subsequently reduce the weight of products made of structural and electrical Al-Mg-Si materials. Severe plastic deformation is one of the promising methods of obtaining a significant increase in properties. In this paper a new SPD method is investigated – Multi-ECAP-Conform, characterized by the fact that per one processing cycle the accumulation of true strain is provided up to е>2.5. In order to study the stress-strain state effect on the mechanical properties of the aluminum Al-Mg-Si alloy, mathematical and physical modeling with the modern software Deform-3D were applied, as long as the well-established techniques of assessment of materials mechanical characteristics after plastic processing. The obtained results demonstrate the adequacy of using mathematical and physical modeling to estimate the stress- strain state by Multi-ECAP-Conform.

This paper presents the results of the computer and experimental study of a promising technique of severe plastic deformation (SPD) – Multi-ECAP-Conform (M-ECAP-C) for the fabrication of long-length nanostructured billets (wire rods) with an enhanced strength and electrical conductivity from the aluminum alloy EN-AW 6101 in a single processing cycle. On the basis of the obtained results, a new rational geometry of the pressing channel for the M-ECAP-C technique has been developed. The stress-strained state, structure and mechanical properties of pilot samples of wire rods have been studied. It has been established that processing by the new technique leads produces enhanced mechanical and physical properties.