Research of stamping of unequal channel bars. Part 4. Deformed state of the workpiece when extruding channels. 1. Deformations in the area of wall formation

Determination of the deformed state of the workpiece at free extrusion of channels is considered. Formulas are obtained that make it possible to determine the accumulated deformations at a given point of the center of plastic deformation and the extruded walls of the product for any working stroke of the punch. Keywords: die forging, extrusion, misalignment, punch, matrix, plane deformation, accumulated deformation, hardening. [email protected]

PUNCHING CUPS WITH BOTTOM FLANGE BY DIRECT EXTRUSION WITH COUNTER-PUNCH. DETERMINATION OF THE DEFORMED STATE IN THE SECOND PERIPHERAL REGION OF PLASTIC DEFORMATION

Using the theory of plastic flow according to the method of A. L. Vorontsov, formulas are obtained that are necessary for calculating the accumulated deformations obtained by extruding with a counter-punch a peripheral region adjacent to a container with a matrix. The average accumulated deformation in both peripheral regions was determined.

Analysis of Tribological Properties in Disks of AA-5754 and AA-5083 Aluminium Alloys Previously Processed by Equal Channel Angular Pressing and Isothermally Forged

In the present study, the wear behaviour of two aluminium alloys (AA-5754 and AA-5083) is analysed where these have been previously processed by severe plastic deformation (SPD) with equal channel angular pressing (ECAP). In order to achieve the objectives of this study, several disks made of these alloys are manufactured by isothermal forging from different initial states. The microstructures of the initial materials analysed in this study have different accumulated deformation levels. In order to compare the properties of the nanostructured materials with those which have not been ECAP-processed, several disks with a height of 6 mm and a diameter of 35 mm are manufactured from both aluminium alloys (that is, AA-5754 and AA-5083) isothermally forged at temperatures of 150 and 200 °C, respectively. These thus-manufactured disks are tested under a load of 0.6 kN, which is equivalent to a stress mean value of 18 MPa, and at a rotational speed of 200 rpm. In order to determine the wear values, the disks are weighed at the beginning, at 10,000 revolutions, at 50,000 revolutions and at 100,000 revolutions, and then the volume-loss values are calculated. This study was carried out using specific equipment, which may be considered to have a block-on-ring configuration, developed for testing in-service wear behaviour of mechanical components. From this, the wear coefficients for the two materials at different initial states are obtained. In addition, a comparison is made between the behaviour of the previously ECAP-processed aluminium alloys and those that are non-ECAP-processed. A methodology is proposed to determine wear coefficients for the aluminium alloys under consideration, which may be used to predict the wear behaviour. It is demonstrated that AA-5754 and AA-5083 aluminium alloys improve wear behaviour after the ECAP process compared to that obtained in non-ECAP-processed materials.

Technological aspects of production of thin sheets for aircraft construction based on Al – Mg – Sc alloys

Review of the possibility of replacing thin sheets (0.5 mm) of alloy 2024 with sheets of a new alloy of the Al – Mg – Sc system alloyed with transition metals. New material is lighter than 2024 but save high-level properties such as corrosion strait, satisfactory weldability, static strength, ductility and crack resistance. Review of the possibility that in the case of using extrusion technologies through the matrix with a periodically changing profile. The coefficient of accumulated deformation is increased by almost 2 times compared with extrusion through a cone matrix. This allows to improve the developed structures with the same drawing coefficients equal to 4. It was shown that mixed structure with small-angle dislocation subgrain boundaries and strongly misoriented boundaries of fragmented structures forms in sheets with a thickness of 0.5 mm.

Swell–Shrink Behavior of Rubberized Expansive Clays During Alternate Wetting and Drying

The present study examines rubber’s capacity of improving the swell–shrink potential of expansive clays. Two rubber types of fine and coarse categories with different geometrical features were considered. The test program consisted of standard Proctor compaction and cyclic wetting–drying tests. Scanning electron microscopy (SEM) analysis was also performed to identify the soil–rubber amending mechanisms, and to observe the evolution of fabric in response to alternate wetting and drying. Cyclic wetting–drying led to the reconstruction of the soil/soil–rubber microstructure by way of inducing aggregation and cementation of the soil grains. The greater the number of applied cycles, the lower the swell–shrink features, following a monotonically decreasing trend, with the rubberized blends holding a notable advantage over the virgin soil. The tendency for reduction, however, was in favor of a larger rubber size, and more importantly the rubber’s elongated form factor; thus, predicating a rubber size/shape-dependent amending mechanism. The soil–rubber amending mechanisms were discussed in three aspects—increase in non-expansive content, frictional resistance generated as a result of soil–rubber contact, and mechanical interlocking of rubber particles and soil grains. The swell–shrink patterns/paths indicated an expansive accumulated deformation for the virgin soil, whereas the rubberized blends manifested a relatively neutral deformational state, thereby corroborating the rubber’s capacity to counteract the heave and/or settlement incurred by alternate wetting and drying.

Влияние поверхностного слоя на комплекс свойств тонкой проволоки из сплава на основе TiNi

We have studied the influence of the surface layer on the parameters of the multiply repeated shape memory effect, developing stresses, characteristic temperatures, and intervals of martensitic transformations in thin (1 mm diameter) wires made of TiNi-based alloys. Examination of the surface layer structure showed that, in 1-mm-diameter TN-1V grade alloy wire, the oxide layer is about 15 μm thick and consists mostly of titanium, nickel, oxygen, and carbon. Removal of this surface layer leads to an increase in the maximum accumulated deformation, shift of the temperature interval of formation toward higher temperatures, and increase in the strength and plasticity characteristics.

Evolution of BrOCS 5-5-5 Alloy Microstructure and Mechanical Parameters under Intensive Plastic Deformation Conditions

The complex approach to the microstructure and microhardness parameter of BrOCS 5-5-5 changing dependences out of hardening degree are presented. The acquired results correlate with the earlier research, but give us new knowledge about the microstructure and microhardness parameter value changes depending of the deformation degree. That allows predetermining the accumulated deformation degree at bush type hardening process, for example – plain bearing liners or structural elements in the form of axial symmetry tybes. The prediction of the microstructure and mechanical parameters – microhardness parameter value in dependence of accumulated degree in particular becomes possible. The microstructure research carried out allows predetermining the necessary deformation degree for the studied material for its further application.