Seznam abstraktů 2015: SEKCE B - TVÁŘENÍ KOVŮ

Plane strain and uniaxial compression tests are generally used for characterization of a material constitutive behavior during hot forming. Interpretation of the results obtained by such tests is complicated by flow inhomogeneity occurring in the specimen volume and temperature variations. Inverse analysis is an effective instrument allowing one to take these factors into account and obtain more accurate constitutive equations of a material. In this study the constitutive behavior of HC420LA steel was examined by plane strain and uniaxial compression testing on Gleeble 3800. Finite element simulation of the tests was performed in order to evaluate the influence of friction factor on flow inhomogeneity and its effect on stress-strain curves obtained as a result of testing. Inverse analysis was used to correct the initial Gleeble data and obtain accurate constitutive equations of the material.

The effect of Thermomechanical Processing, using cold deformation with the combination of post deformation annealing and induction hardening based on the of dislocation-disclination structure inheritance effect on the strength, ductility, and torsion static strength has been studied. The metal with an initial structure of lamellar pearlite has shown to be more advantageous with respect to the strengthening intensity during cold rolling and the combination of mechanical properties after the TMP. It can be seen that in the studied strain range (up to ε  60%) the hardness of the high-strength middle carbon steel with the structure of lamellar pearlite is 20 - 40% higher than that of the steel with the structure of granular pearlite. Steel with the initial structure of lamellar pearlite is strengthened more intensely and its final heat treatment with the use of induction hardening to martensite and low temperature tempering show the inheritance of fragmented dislocation substructure result in the highest static torsion strength and the best combination of other mechanical properties.

Dual Phase (DP) and Complex Phase (CP) steels with the multiphase microstructure belong to the modern steel group called Advanced High Strength Steels (AHSS) and are used very often in the automotive industry. Third generation of these steels is now widely investigated. Practically, these steels are characterized by a compromise between high cold-workability of steel sheet and rigidity of a car body draw-piece. To design thermo-mechanical rolling of DP and CP steels a knowledge of their hot workability and multi-stage cooling rate is of primary importance.
The paper focuses on rolling conditions, microstructure and mechanical properties of two different AHSS steel grades. For whole experimental investigations the own cast of DP and CP steels were made, from which the samples for all laboratory hot rolling and mechanical tests were prepared. In order to determine the cooling curves and the start and finish temperatures of phase transformations, the dilatometric investigations were performed. The designed CCT curves were the fundamentals of the planning of further research, e.g. computer simulation and hot rolling in laboratory conditions. On the basis of investigations realized by numerical FEM calculation and plastometric tests (Gleeble), the thermo-mechanical conditions resulting in a fine-grained structure were designed. The level of diversified microstructure and thus wide range of mechanical properties by the use of laboratory hot rolling and multi-stage cooling processes were determined. It was pointed out that apart from chemical composition the thermo-mechanical rolling conditions have great influence on phase composition and mechanical properties of the investigated DP and CP steel strips. The results of the analysis carried out in this work provide useful data for the designing of thermo-mechanical rolling of DP and CP steel strips, which have multiphase microstructure and diversified mechanical properties.

The problem of calculations and experimental identification of the residual stresses in hot-rolled strips is extremely important. Residual stresses become of practical importance when the laser cutting of strips is applied. The factors influencing the residual stresses include the non uniform distribution of elastic-plastic deformations, phase transformation occurring during cooling and stress relaxation during rolling and cooling [1]. The goal of this paper is accounting for phase transformations in modelling stresses occurring during laminar cooling and coiling of steel strips. For this objective the dilatometric tests were performed for all steels investigated in the project. Avrami model [2] was modified by introduction relation of the main coefficient on the temperature. Coefficients in the phase transformation model were identified by the inverse analysis of the dilatometric tests. The inverse algorithm developed by the Authors [3] was used in the identification. The optimized model was implemented in the FEM model of cooling of hot rolled strips during laminar cooling and in the coil. The advantage of the developed model and computer program is its ability to perform quick calculations in industrial conditions, accounting for the dilatometric effect due to phase transformations. Numerical tests confirmed good predictive capabilities of the model
References
[1] Milenina A., Kustra P., Kuziak R., Pietrzyk M., Model of residual stresses in hot-rolled sheets with taking into account relaxation process and phase transformation, Procedia Engineering 81, 2014, 108-113.
[2] Avrami M., Kinetics of phase change I, J. Chem. Phys., 7, 1939, 1103-1112.
[3] Kondek T., Kuziak R., Pietrzyk M., Identification of parameters of phase transformation models for steels, Steel GRIPS, 1, 2003, 59-66.

The paper deals with a numerical simulation and material-technological modelling of the forming and the subsequent air-cooling of the select type of a closed-die forging. The numercial simulation provided information about material flow, strain and strain rate during the forming and about temperature distribution during the forming and subsequent air-cooling in selected locations of the given forging. The material-technological modelling then allowed to analyse the microstructure on samples which were taken from the locations of the closed-die forging corresponding to the numercial simulation. By means of these techniques (the numerical simulation and the material-technological modelling), the new controlled cooling technology were tested. The controlled cooling technology should replace the current heat treatment (quenching and tempering). Both these techniques were used for the closed-die forging made of C45 steel in Kovárna VIVA a.s. Results from the numerical simulation and the material-technological modelling are summarised in the paper and are compared with the real production process.

Stress and stress conditions during shape rolling of experimental billets were analysed. Photoplasticimetry, the theoretical basis of which is briefly described, was applied as the evaluation method. This method is advantageous for evaluating stress and strain conditions since it enables to determine directions of the main strains in each point of the deformed material in the real deformation zone, as well as differences between them. The obtained data can subsequently be also used to solve other issues of static conditions of equilibrium by applying the methods of shear stress differences and successive approximation.

Mechanical properties of closed die forgings reflect their microstructure which is formed during the manufacturing process. There are a number of process factors at play which govern the final microstructural condition of the forged part. Besides the amount of working and the forging temperature, there is the post-forge cooling rate which has a decisive influence on the resulting microstructure. An important pre-requisite for dealing with these aspects is the definition of the input requirements and the boundary conditions. For instance, an input requirement may involve obtaining the desired microstructure within the entire forged part. Boundary conditions include the actual capabilities of the forge shop in terms of the control over the forged part’s cooling. Hence, predicting the resulting properties of the forged part’s material is a complex endeavour. In ordinary forge shops, there is no other way of finding these properties than by trial and error, which is rather demanding. It is time consuming and costly because a number of cooling routes must be tried in the plant. An alternative to this is material-technological modelling. It is a highly effective method of modelling the cooling of forgings without interfering with the production. By this means, the optimum manufacturing route can be found which, once implemented, delivers the desired microstructure of the forged part at minimized cost.

Classification of the existing phase transformation models with respect to computing times and predictive capabilities is presented in the paper. For optimization of manufacturing cycles in materials processing simple models, which describe kinetics of phase transformations, are needed. Three models are proposed in the present paper. The first is an extension of the JMAK model [1] based on introduction of the dependence of the main coefficient on the temperature. The second is an extension of the Leblond model [2]. Authors of [2] have proved that the rate of transformation is proportional to the difference between the equilibrium and the current volume fraction of the new phase and inversely proportional to the time constant of the transformation. This approach is based on the first order differential equation. Introduction of two time constants (second order inertia term) was the main new feature of our model comparing to the Leblond approach. The third group of models is based on a solution of the carbon diffusion equation in the austenite [3]. Capabilities of the models regarding prediction of microstructure after transformation were evaluated. All models were validated by comparison their predictions with the results of dilatometric tests performed for the DP 600 steel. The good practice guide concerning selection the best model for a particular application is the main output of the work.

References:
[1] Avrami M., Kinetics of phase change I, J. Chem. Phys., 7, 1939, 1103–1112.
[2] Leblond J.B., Devaux J., A new kinetic model for anisothermal metallurgical transformations in steel including effect of austenite grain size, Acta Metallurgica, 32, 1984, 137-146.
[3] Pernach M., Bzowski K., Pietrzyk M., Application of numerical solution of the diffusion equation to modelling phase transformation during heating of DP steels in the continuous annealing process, Computer Methods in Materials Science, 12, 2012, 183-196.

Dynamic recrystallization processes in heat-resistant Ni-based alloy was investi-gated depending on temperature, strain rate and deformation ratio. Recrystalliza-tion intensity is determined by the temperature and deformation conditions. The factors that increase the degree of dynamic recrystallization include temperature and amount of strain increasing, as well as decreasing of strain rate. Increasing the volume fraction of recrystallized structure causes a uniform fine-grained structure. Detailed microstructure analysis of heat-resistant Ni-based alloy after dynamic recrystallization was performed.

An integral computer model/program for simulation of steels hot rolling on mill 2000 of SEVERSTAL was developed. The model provides for calculating the following:
- temperature distribution over the cross section of a rolled strip at any location along its length;
- rolling forces;
- austenite microstructure evolution under hot rolling taking into account grain growth, dynamic/static recrystallization and strain induced carbonitrides precipitation;
- austenite transformation during accelerated strip cooling at the run-out table accounting for formation of polygonal ferrite, pearlite, bainite of different morphology, and martensite;
- mechanical properties of rolled strips (yield stress, ultimate tensile stress and relative elongation).
The present model was calibrated using an extensive data base on rolling regimes and forces, measured temperatures and final mechanical properties for a number of steel grades rolled on mill 2000 of SEVERSTAL with chemical compositions covering the following ranges of alloying elements content: С(≤0.65); Mn(≤2.0); Si(≤1.0); Cr(≤0.9); Ni(≤0.6); Cu(≤0.5); Mo(≤0.4); Nb(≤0.05); V(≤0.065); Ti(≤0.06). The calculation results for temperatures, rolling forces and mechanical properties are in good agreement with the experimental data. The computer program STAN 2000 has a well-designed and convenient interface. The program is widely used in practice of industrial strip production on mill 2000 of SEVERSTAL for working out new and optimizing existing hot rolling and accelerated cooling regimes.

The paper presents results of numerical simulation of the asymmetric rolling process for band with shape ratio h0/D = 0.072 – steel grade S355J2G3. The study was conducted to determine the differences in the impact factor of different kinds of asymmetry on the band bending after leaving the deformation zone and the power parameters of rolling process. Introduction of single asymmetry, by varying the peripheral speed of the work rolls, does not have an effect on reduction of force parameters values. Based on the survey it was found that simultaneous introduction of second asymmetry, by varying the diameter of the work rolls, allows to lower rolling force and it also allows to obtain flat band after rolling process.

Ferromanganese TWIP steels with the manganese content of 17-20 % are fully austenitic and non-magnetic, without phase transformation. Due to the application of the twinning mechanism the TWIP steels can satisfy numerous technical requirements for production of the new generation of cars. Basic experimental results of TWIP steels exhibit high ultimate tensile strength from 600 to 1100 MPa, as well as extreme values of ductility in the range from 60 to 90%. Castings from the Fe-Mn-C alloys were prepared by method of plasma and vacuum melting. They were gradually hot rolled by three consecutive rolling sequences (first to the height of 18 mm, then to 11 mm, and finally to 3 mm), the samples were then cold rolled metal with reduction of 15%, or 30% to the final heights of 2.2 mm or 2.7 mm. After the second rolling the samples with dimensions of 10x15x20 mm were prepared for stress-relaxation testing on the GLEEBLE 3800. In intermediate phases the samples were taken for metallographic analysis. Dimensions of the samples did not allow execution of tensile tests, that is why only the hardness was measured. The main task was to keep the samples in plastometer GLEEBLE under stress in jaws after deformation e = 0.5, followed by subsequent analysis of the recovery curves and determination of times t for selected portions of the healed structure X with display of the Avrami curves.

Consolidation of material voids is one of the most important goals of the primary metal forming processes. The paper describes a metal forming method where compression is accompanied with transverse, reciprocating motion of a die. It causes additional shear stresses in a workpiece which change in an oscillatory manner. In consequence, a severe plastic deformation can be obtained. A series of experiments and corresponding simulations has been conducted in order to evaluate the effect of additional shear stresses generated during upsetting on material void closure behaviour. The usual upsetting tests have also been performed for comparison. Drilled workpieces have been used in both cases, with voids located in several specific areas on their cross-sections. Two different void orientations towards the transverse punch motion and three variants of the compression process have been analysed. The most important benefits that can be achieved by incorporating additional, oscillatory-changing shear stresses in primary metal forming processes have been presented in a summary.

This paper deal with evolution of plastic properties of drawn steel wire for steel ropes during cold drawing. Drawing process is performed using three types of pass schedules. Pass schedules vary in size of the partial deformation and of course the number of passes. The first one is the standard (7 passes) schedule used in drawing mills, two other ones are experimental (6 and 5 passes). The principle is reduction of the number of passes and thus increasing the partial deformation while maintaining the overall deformation. In this paper we describe influence of size of partial deformation on the final plastic properties (number of torsion to fracture and number of bends to fracture). The tests were conducted in accordance with the ČSN ISO 7801 standard Metallic Materials - Wire - Reverse bend test and ČSN ISO 7800 standard Metallic Materials - Wire - Torsion test. Tensile test and metallographic analysis were also conducted.

The influence of intensive plastic deformation on compacted Al powders was evaluated. The samples subjected to deformation processing were prepared from powder particles with diameters between 20 and 45 μm, pre-compacted using double-step cold isostatic pressing (CIP) at 200+300 MPa applied for 30 seconds each and subsequently vacuum sintered at 500°C for 60 min. Analyses of chemical composition of the sintered samples were carried out using scanning electron microscopy, while microhardness measurements were performed to evaluate the degree of compaction. The results showed increasing microhardness with increasing total imposed strain. Greater refinement of microstructure was achieved by increasing degrees of processing.

To investigate a possibility of grain refinement of low-carbon steel was utilized the universal plastometer Gleeble 3800 which is installed in Regional materials science and technology centre on VŠB-TU Ostrava. Through dilatometric tests of the investigated steel, performed at various heating and cooling rates, were determined the transformation temperatures Ar1, Ar3, Ac1 and Ac3. These temperatures were employed at the proposal of two following types of experiment performed to refinement a prime grain of the examined steel. A first set of the tests contained an annealing of the examined steel with a cyclical change of the temperature. By a metallographic analysis of annealed samples was found out the samples annealed at the temperatures 880 and 530 °C with the soak time of one second on annealing temperature and cooled down or heated up respectively by the rate of 10 °C•s-1 showed the finer grain even after one cycle. Increasing number of the cycles caused a decreasing of ferritic grain. A second set of the test contained a cyclic deformation of the examined steel, which was consisted by a combination of pressure and tension at given temperature. The deformation temperature, a size of the absolute strain, a soak time between the individual cycles and a number of the individual cycles were chosen as variable parameters. There was proven by the metallographic analysis of the each cyclically deformed sample the selected parameters of deformation did not lead to a required refinement of microstructure of the examined steel.

Austempering is a special isothermal heat treatment that can be applied to ferrous materials for increased strength and toughness. The properties of austempered ductile iron are dependent on both chemistry and heat treatment. In this study Different cycles of austempering process applied Due to the effect of heat treatment cycle on the metal matrix structure and tensile properties of GGG70 S.G. iron for of Peugeot 405 crankshaft. This process has been done in different temperature 280, 300, 320, 350 and 365 ͦC the microstructure and mechanical properties of samples have been studied by OEM and tensile test respectively. Finally Surface fraction investigated by SEM. The results show, ductile cast iron undergoes a remarkable transformation when subjected to the austempering heat process. According to tensile and hardness test yield strength, tensile strength and hardness decrease with increasing of austempering temperature.

An in-line heat treatment of rolled materials is becoming frequently used by hot rolling plants. This method achieves the required material structure without the necessity of reheating.
This paper describes a design procedure of cooling sections for obtaining the demanded structure and mechanical properties.
Experimental stands, applied for the cooling study of steel samples, were built at the Brno University of Technology. The first experimental stand enables to simulate a variety of cooling regimes and evaluate the final structure of the tested samples which are instrumented by set of thermocouples indicating the temperature history of the tested material. The second experimental stand is a tool for the design of the cooling sections which can ensure obtaining demanded heat treatment procedure and demanded final structure. The HTC history at the surface is gained as an output of inverse task.
Mathematical model and its implementation into the software tool for computer simulation of heat treatment processes (quenching and tempering) of steel is presented. Heat transfer boundary conditions obtained from test on experimental stand are used for calculation of cooling curves followed by prediction of microstructure after austenite transformation and final mechanical properties as hardness, tensile strength and yield stress. Verification and practical examples of metallurgical predictions for tube products are presented.

Steel production is connected with high temperatures at which the steel reacts with oxygen in the surrounding atmosphere, creating scales on its surface. One of the most promising technologies for removing these scales when the steel is still very hot is hydraulic descaling. A row of high pressure flat jet water nozzles is usually used, with the feed pressure usually ranging between 10 and 40 MPa. The descaled material usually moves under the spraying nozzles. For most flat products, several nozzles arranged in a row must be used because the spray width of the nozzle is smaller than the width of the sprayed material. The steel surface where the scales are sprayed away by two adjacent nozzles is called the overlapping area. This area is dramatically overcooled during the typical configuration with an offset angle of 15° and an inclination angle of 15°. For this paper, both the typical and a new configuration with an offset angle of 0° were measured. Cooling homogeneity measurements were made to see the improvement in cooling homogeneity with the new configuration and spray impact pressure distribution measurements were made to see the size and shape of pressure distributions in the overlapping area for both configurations. Obtained results are presented and any improvement with the new configuration is discussed.

The mandrel bar, which is an inner tool for the mandrel rolling process, plays an important role in obtaining good inner surface quality and higher wall thickness accuracy in seamless pipes. During rolling, the mandrel bar is exposed to severe conditions, such as high temperature and rolling load. As a result, heat cracks are generated and fatigue cracks are also propagated on the bar surface. These cracks are a cause of scratch defects on the pipe inner surface and seizure between the bar and pipe.
The object of this research is to clarify the mechanism of bar damage in single stand rolling. An FE analysis and model experiment were conducted to study the stress distribution of the bar during rolling. It was found that large tensile stress occurred in the rolling direction at the flange areas and the caliber bottom just before and after roll bite of the bar. Especially, the rolling direction stress at the flange areas was distributed deeply and highly. It is considered that fatigue cracks on the bar surface are propagated by these stresses. In addition, the influence of rolling conditions on the stress in the rolling direction was also investigated by the changing the friction coefficient between the bar and the pipe inner surface, the deformation resistance of the material being rolled and the diameter and caliber shape of the grooved rolls. As a result, the influence of rolling conditions on the bar stress distribution, which causes bar damage, was evaluated quantitatively in this research.

The production of precision seamless steel tubes in Železiarne Podbrezová requires a detailed microstructural analysis of plastic deformation during cold forming on draw benches. Speaking of microstructural analysis we actually mean the impact of plastic deformation on the microstructure is being investigated as well. For this, a detailed study of deformation and dislocation interaction mechanism during cold forming is necessary.
In this paper we present the microstructural analysis of selected material states focusing on the grain size of ferrite and the volumetric content of pearlite. The yield stress strengthening contribution has been estimated using additive law and the deformation strengthening contribution after normalizing has been estimated using the law of geometrically necessary dislocations, allowing us to compare both contributions – grain strengthening Rz and dislocation strengthening RD, respectively.

The present paper presents experimental verification of cross-rolling parameters used at production of seamless tubes. We tested the influence of transport angle and diameter billet on the axis force. Sufficient magnitude of this force allowed the smooth flow of metal through the piercing plug. Experimental work was carried out on a laboratory rolling mill with three-roll arrangement 120° around the circumference of the billet. Rolling was carried out using a special blunt plug. The technological parameters were selected as follows: speed of work rolls from 100 rpm, transport angle 6°, toe angle 0°, temperature 1000°C, reduction of the diameter 5 and 10%. Sufficiently large reserve of the axial force was necessary to prevent blinded tube making, which decreased the production cycle and thus also capacity of production. The transport angle has the primary effect on magnitude of the axial force, which for the given calibration work rolls shows the possibilities and limitations of the technology with such rolls.

During recent years, deformation technologies based on the severe plastic deformation (SPD) developed extensively. SPD methods are effective for refining microstructures of different materials, which lead to a significant improvement in strength properties. In this case, the researchers had the important task of improving the quality of workpieces with minimal material and energy costs. During a deformation process, carried out with the aim of structure refinement, large macroscopic deformation has a great influence. Currently, we are actively developing innovative ways of forging based on large macroscopic deformation, which can intensify the strain imposed into inner layers of an ingot. The work is aimed at solving the problem of improving quality of preforms produced by fullering with the implementation of severe plastic deformation. Carry out computer simulation of fullering technology and studied stress-strain state metal by deformation.

At equal-channel angular pressing (ECAP) there is an essential study of metal without change of a form and the dimension of billet. It billet use for the follow production of quality details.
In this work the way of receiving finished products cogwheels types by combination of ECAP with forming of billet in one technological operation is studied. Thus decrease in costs of production of products will be reached.
Researches are conducted in the program complex DEFORM 3D. By simulation the step matrix output channel had a form of the cross section corresponding to contours of the received cogwheel was used. Transition from a cylindrical form to the final is executed smoothly, diameter of initial billet has to correspond to the external diameter of a cogwheel.
When forming a cogwheel in the output channel back-pressure due to changes of a form is created.
After receiving billet with the issued contours, it is cut at lengths corresponding to cogwheel thickness. The analysis of the obtained results shows that equal channel angle extrusion of alloys on titanium base favours the improvement of metal quality.

The article presents the results of preliminary studies on the formability of aluminum alloy sheet in the process of Incremental Sheet Forming (ISF). For tests was used aluminum alloy sheet 2024. Laboratory stand and measurement techniques that have been used to analyze the process are presented. Preliminary studies consist of the analysis of the thickness distribution with the photogrammetric method, testing the mechanical properties of the product and microscopic observations.

In a development of a new type of solar absorbers is required to modify an absorption area to the system of pyramidal cavities. It is necessary for higher absorption effect and less dependence on incidence angle of solar radiation. Due to complicated final surface, the hydroforming was chosen as a production technology. This paper deals with numerical simulations of forming operations and an identification of critical areas. Furthermore, the die shape and a weldment - sheet blank optimization are performed. A theoretical simulation of the hydroforming process was carried out by using ANSYS software.

The microstructure and mechanical properties of Aluminium alloy (AA 5083) processed through Repetitive Corrugation and Straightening (RCS) are studied. The RCS process consists of corrugating a flat specimen with a pair of systematically grooved dies and straightening was done with two parallel flat dies. The aluminium samples were subjected RCS process using two different die sets namely truncated V groove dies (Die 1) whose breath=height=5mm and θ=30° and another set of dies with circular profile with radius=10 mm (Die 2) both having different die parameter. The specimens were subjected to maximum 8 passes. The grain refinement is studied form the microstructure examination using EBSD and TEM. The mechanical properties such as Tensile strength, Hardness and the grain size were compared. The Tensile strength and Hardness found to be increasing with respect to the number of passes. The tensile strength increased up to 25% in the sixth pass when compared to the parent material. But the strength and hardness values were reduced at 8^th pass due to the surface cracks. The EBSD analysis showed the significant grain refinement in the alloy. The studies showed that the Die - I is superior to Die - II for grain refinement.

As a major consumer of energy the steel producers are always mentioned as interesting field of investigations. During the thermal processes in metallurgy, it is important in many cases to know the exactly particularities of heat transfer in a complex system. In the case of steel semi-finished products heating, the most of the models refers to the heat exchange by convection and radiation or to the heat transfer by conductivity inside the material. The heat transfer by radiation has an important component: the value of the heated surface by radiation, but also the more exactly determination of the values of the radiation coefficient. The aim of this analyse is to establish the basic relations for a model in order to help to evaluate the parameters of the heat transfer and energy consumption in the case of some metallurgical heating furnaces for billets reheating. The article refers also to "the equivalent surface of heat transfer" (a new terms proposed by the author), subject to the way of billets disposal in various types of furnaces used in the rolling-mills factories.
Starting from considerations about the burning process of the fuels, there are established relations between the heat exchange coefficients, energy and metallic material saving.
We have also to consider that it is an important difference between various types of continuous operating furnaces: while in the pusher-type furnace the billets may be disposed only one near the other, without free spaces between them, the walking-beam furnace or the rotary hearth furnace allows the disposal of the billets at the required distances.
Modifying this distance there is the possibility of acting upon the billets stationary time in the furnace, upon temperature distribution in the section of the billets, upon oxidation and decarburization reduction.
Saving energy and lost metal due to the oxidation process, means to have a cleaner environment. The article offer also a model to calculate the temperature in the furnace (temperature of the flue gases) taking in consideration the global heat exchange, the technological temperature of the billet in order to evaluate the thermal energy looses.

In this work is described the effect of pre-heat-treatment on the microstructure and mechanical properties of different grades of steel before equal-channel angular pressing. Nomograms with mechanical properties of different grades of steel till and after annealing were obtained. It was found that the annealing of the second kind is an appropriate operation began before pressing.

The effect of preliminary heat treatment and equal channel angular pressing in step die on the microstructure and properties of steel grade 45 are analyzed. There is revealed that the grain size after equal channel angular pressing depends little on the preliminary heat treatment, however, annealing reduces the hardness of steel, which helps to reduce the effort of pressing on the first passes. Ultra-fine grained structure in steel of grade 45 is retained at heating up to 400°C, and only at heating up to 500°C, the recrystallized grains appear, substantially free of dislocations, with balanced triple grain junctions.

The effect of rotational and travelling speeds and down force on the torque in Friction Stir Processing (FSP) process are presented. The relationship between the rotational speed and torque was modelled by an exponential function. The dependence of the travelling speed and down force affecting the torque was successfully approximated by the linear functions. To find a dependence combining the spindle torque acting on the tool with the rotational speed, travelling speed and the down force, the RSM methods have been applied. Studies have shown that the increase of the rotational speed cause decrease of the torque and increase the travelling speed and down force cause increase of the torque in the same time. The relationship between parameters of the process and the temperature of the surface, were presented. Tests were conducted on casting aluminium alloy AlSi9Mg. The experimental results and analytical calculation were compared.

The article presents the results of theoretical and experimental studies of stress and strain states, power modes and limits the deformation drawing operation with wall thinning symmetric machine parts of double-layer anisotropic materials in conic matrices.

Process principles forming blanks pressurized gas and diffusion bonding may be employed in the manufacture of multilayer mesh sheet structures.
The sheet material to be stamped usually is anisotropic mechanical-cal properties due to the brand of the material, technological modes of its receipt, Coto paradise contributes to sustainable flow of technological processes of metal forming.
The results of theoretical and experimental studies of the process of isothermal pnevmoformovki cellular elements multilayer sheet structures of the mate-rial anisotropic in creep mode. A process of forming is carried out in two steps: the shell and deforming the free constraint in forming angular deformation of structural elements.