No abstract

Mechanical properties of specimens were researched for model analysis of stress-strain behavior in the stress concentration zone for plate structures using aluminum alloys. Traditional and new structure materials including Russian (1915T and 1565ch) and foreign (6082 – Russian analogue AD35) developments with different alloyage systems (Al-Mg, Al-Mg-Si and Al-Zn-Mg accordingly), strengthening methods, corrosive resistances and welding capacities are studied. Strain and fracture resistance is shown for axial and eccentric tension and for impact bending in the temperature range from -70 to +20°C. Acquired results allow us to designate loads reasonably for structure design using aluminum alloys and estimate their durability.

Resistance to low-cycle fatigue of hot-rolled plates manufactured from alloyage system Al-Mg-Si alloy 6082 is researched. Cyclic stability of alloy and cyclic proportional elastic limit were defined during tests of specimens without cracks loaded along the rolling direction using curves of cyclic strain and their generalization. Properties used for design of prefabricated structures from thick aluminum plates from alloy 6082 operating in the conditions of low-cycle fatigue are received.

Comparison of welding influence on structural strength of Al-Mg-Si alloy (AW6082-T6), supplied with 10 mm thick sheets, is made. Within the research tension and impact tests of welding joints, made with argon-arc and friction stir welding, were carried out. During the research we observed the following: strength and plasticity decrease for welding joint zones, impact strength increase of weld metal in friction stir welding, welding defects influence on joint strength.

The reasons for the appearance of cracks in the mounting connection, which is an unequal angle obtained by a plate at a right angle of 8x210x100, are investigated. The limited information received at the standard scope of material tests is shown to assess the processability of the product. Investigation of the composition, structure and viscosity of the material made it possible to establish that in order to obtain a quality product from rolled steel of St3sp, it is necessary to make changes in the technological operations of cutting and bending the production of the part. When performing the cutting operation of sheet metal, the long side of the plate (210 mm) should be placed along the direction of the fibers of the structure. During bending, the edge of the folding of the sheet must be made across the rolled fiber. For steels that are prone to splitting along the fibers of the structure, correct cutting of the sheet will prevent the formation of cracks along the stretched bending surface and fatigue failure during welding and operation of the assembly line.