The article presents tests results of metalforming of magnesium alloy. Materials for tests were ingots sized ϕ 40 x 90 mm from magnesium alloys marked with symbol AZ61, WE43. Before the shaping process the ingots underwent heat treatment. As a result of conduction of the deformation processes there were rods achieved with diameter of 8 mm. There were axisymmetrical compression tests conducted on the samples taken from rods in temperature range from RT to 350ºC in order to determine the plasticity and formability of the alloy AZ61 and WE43. Static tensile test was conducted in room temperature (RT), in 300ºC and in 350ºC. With the use of light and electron microscopy techniques the changes which occurred in the microstructure of magnesium alloys in initial condition and after plastic deformation (classic extrusion, KoBo method extrusion) were described. Analysis of microstructure was completed with the quantitative analysis with the use of Metilo program. Stereological parameters were marked such as mean grain diameter, mean surface area and shape factor. Measurement of grain size was conducted with the use of surface method based on the images registered by light and scanning microscopes.
The technological process of rolling of seamless tube consists of three stages. In the first of them, a thimble - shaped hollow is produced from the cast ingot (usually square), which in the second stage is rolled into the thimble. The next part of the manufacturing process is the main rolling on the mandrel, where intensive elongation is associated with the reduction of the cross-section. The last stage is the reduction rolling or calibration rolling in which the tubular thimble is shaped into a hot rolled tube. During research carried out in industrial conditions by the researchers of the Institute of Metal Forming and Safety Engineering of the Częstochowa University of Technology, aimed at increasing the efficiency of the tube rolling process in a pilgrim mill, the influence of the technological parameters of rolling on the quality of finished tube and the reduction of technological waste was found. The documentation and analysis recording data have shown that there is a possibility of multi-component adjustment of the extension mill settings affecting the flow behavior in the rolling gap. Proper selection of parameters will allow to control the metal flow behavior of the rolling thimble in a way which improves the quality of tubes manufactured by the pilgrim method. The paper presents preliminary results of numerical tests on the influence of the rolling process of a thimble in an elongation rolling mill on the material flow. Numerical modeling was carried out using the FORGE 2.1 NxT computer program. Based on results of computer simulations, the distribution of strain intensity and intensity of strain rate was determined. Based on the theoretical tests, it was found that it is possible to select the appropriate technological parameters to ensure a more even flow of material in the rolling gap and to improve the shape of the thimble after being rolled in the extension mill.
Due to the improvement of efficiency of power equipment (heat exchanger), it has been required to change the arrangement of exchanger tube bodies through the minimization of exchanger tubes bending radius. It was necessary to optimize process parameters and functional parts of forming tool to achieve the required parameters of tube bending. On the bending rail, which is one of the main parts of forming tool was used a newly developed type of cast iron with especially suitable characteristics minimizing a coefficient of friction during forming processes. In this paper we present the obtained results and material features in strain area of exc hanger tubes.
The main of this work is to examine the residual stresses formed during drawing of low carbon steel and the evolution of the mechanical properties.
The low carbone steel studied shows a ferrito-pearlitic microstructure dominated by the beta phase. The fraction of large grains in the ferritic phase is greater than that of the small ones, but it is reversed in the pearlitic phase. This makes it possible to predict the prior existence of residual stresses in the microstructure, but the KAM illustrates a typical curve of a recrystallized material free from any residual stresses.
Like any process based on plastic deformation, wire drawing increases the hardness and tensile strength and lowers the tensile elongation of the drawn wires. At the microstructural level, an elongation of the grains is observed along the drawing axis. The KAM of deformed wires implicitly illustrates the energy stored at the grain level of the ferritic phase and reflects the existence of residual stresses induced by drawing. These evolutions are reflected, at the crystalline level, by the widening and the displacement of the diffraction peaks of the phase alpha (). This explains the formation of first-order residual stresses and second-order stresses at the grain level. It has been found that these stresses appear in each of the studied drawn wires, with different intensities.
The means and techniques used to carry out this study are optical microscopy (OM), scanning electron microscopy (SEM), EBSD analysis, X-ray diffraction, microhardness measurements and tensile tests.
The influence of initial soaking and parameters of hot plastic working on the deformability and microstructure of the IN 718 superalloy have been presented. The research was performed on a torsion plastometer in the range of temperatures of 900 - 1,150 °C, at a strain rates of 0.1 s-1 and 1.0 s-1. Plastic properties of the alloy were characterized by the worked out flow curves and the temperature relationships of flow stress and strain limit. The structural inspections were performed on microsections taken from plastometric samples after so-called “freezing”. The stereological parameters as the recrystallized grain size, inhomogenity and grain shape have been determined. Functional relation between the Zener-Hollomon parameter and the average grain area has been developed and the activation energy for hot working has been estimated.
Knowledge on workability of materials prior to the main production step can lead to a sound product with optimum properties with minimum efforts. In this article an experimental based model is developed being able to predict the hot workability of Sn-5Sb solder alloy. For this purpose, hot compression tests in the temperature range of 300-400 K and strain rates between 0.0005 and 0.01 s−1 are performed to study the shear band formation possibility of Sn-5Sb solder alloy. Taking the advantage of recorded data, hot workability of the alloy was investigated by prediction of shear banding and hot workability maps which indicate the safe and unsafe regions of deformation are derived.
The point resistance welding process is a commonly known method of joining elements in various branches of industry. It is widely used in automotive and aviation industry as well as everyday household appliances. The main issue during the resistance welding process are the anti-corrosion coatings in the form of zinc layer. As part of this research work the development of tools designed for the die forging process of F0 type welding caps which are regularly used during the welding processes of galvanized car bodies in the automotive industry was undertaken. The designed dies were subjected to finite element method (FEM) analysis in the Deform-3D software in order to verify the geometric correctness. The tools were designed in order to allow the manufacturing of welding caps with flash as well as in the flash-free technology. FEM analysis shows the distribution of stresses and strains occurring in the die during both hot and cold forging of welding caps. In addition, the research shows the metal flow characteristics during the plastic deformation, which affects the structure of the material and is crucial in terms of the final properties of the welding caps. The designed and manufactured dies intended for die forging of the welding caps were finally subjected to the empirical research which confirmed the geometrical correctness of the produced welding caps and made it possible to conduct further research on the development of a new generation of alloys designed especially for the production of welding caps in the resistance welding process.
ACKNOWLEDGEMENTS: Authors are grateful for the financial support provided by The National Centre for Research and Development - Research Project No. TECHMATSTRATEG1/347960/6/NCBR/2017.
The paper presents the results of evaluation of the macro and microstructure as well as mechanical properties of rolled bars made from steel 42CrMo4 from continuously cast stock. The macrostructure was examined using Baumann's method and deep etching. Based on the examination of the macro and microstructure, it was shown that discontinuities and internal defects may occur during initial plastic processing of ingots by rolling. For high degree processing, a fine-grained structure is obtained, while for large bar diameters and low degree processing, there may be variations in the grain size in the cross-section. Mechanical properties determined from the static tensile test, impact test and hardness measurements indicate a greater influence of the sampling site than of the degree of plastic processing, which may results from both the quality of ingots and the rolling conditions.
The cold pressing of thin sheets is one of the dominant methods of manufacturing vehicle construction elements. These methods are constantly improving due to the production needs in an increasingly efficient way - economically and technologically effective. In addition, the modern user expects vehicles with eco-friendly features: low-emission, light, safe in operation, durable, corrosion-resistant, recyclable, etc. Car manufacturers are constantly looking for ways to meet these expectations. These expectations define the directions of following research on modern construction materials, e.g. advanced high strength steels (AHSS), multilayer and functional materials And the result of introducing production materials with new special properties, it creates numerous innovation needs in the field of their processing technology. In order to obtain very complicated and asymmetrical shapes of products, the liquid is used instead of rigid stamping tools (hydro-forming), metal materials are plasticized using partial heating (e.g. spinning with heating the area before the roll using a laser) or complete heating of the batch sheet (hot forming). The plates are deformed circumferentially on the instruments with a point tool whose movement path maps the shape of the single point incremental forming. Innovative hybrid solutions combining volumetric and shell forming, liquid treatment and hot forming, and the like are sought after. In this detailed work, the last of these hybrid technologies was analyzed, called quick plastic forming (QPF) with preforming. This technology is based on a new pre-forming process of deep drawing, on an innovative pressing tool with a unique system to regulate the time and pressure of the working liquid inside. The assumptions of technology have been presented. Requirements for the production of drawpieces from standard 5000 series aluminum alloys for the needs of the automotive industry, in relation to the capabilities of the analyzed technology, were compared.
Incremental sheet metal forming is an innovative process with a very wide range of applications, giving many research opportunities. Sheet forming is performed by a typical CNC milling machine, an industrial robot arm or an advanced machining center.
The aim of the researches is to analyze the incremental sheet metal forming process in terms of selection of optimal technological parameters of the process in order to obtain, free of defects, final products. The OPTI BF 30 VARIO numerically controlled drilling - milling machine used in the research was modified to the form of multifunctional post for incremental sheet metal forming operation. Forming process took place on 2XXX and 7XXX series aluminum alloys sheets, used in aerospace industry. The influence of selected parameters like the rotational speed, feed and stroke of the tool, material grade and the diameter of the forming tools, the trajectory of the tool path, as well as the shape and properties of the products was completely analyzed. These parameters: shape and dimension of aluminum sheets were tested using a 3D scanner.
On the basis of the conducted research, possible scenarios of sheet metal behavior during shaping in various conditions were presented as well as effective methods of minimizing the negative effects affecting the quality of the final product.
Results of dynamic tensile tests performed for three grades of carbon structural steel are presented in the paper. The selected steels are typically used for making elements of the road sign support structures. The tests were performed on a flywheel machine that allowed to achieve strain rates corresponding to those obtained during vehicle collisions against fixed objects. Although expected positive stress sensitivity to strain rate was confirmed for all steels, two carbon steels exhibited significantly lower UTS values in tests performed at the highest strain rate (ca. to 1400 s-1) due to their limited formability in such conditions. Fractographic analysis revealed ductile and mixed ductile - brittle character of fractures.
This article deals with evaluation of effect of forging ration on microstructural characteristics of structural steel used for special application such as connecting rods, bolts, arbors, pins, axle arm. Intensity of structural changes during forging is usually determined in dependence on the forging ratio. Forging ratio at elongation is most often calculated with use of simple relations, which are based on the change of cross section of the forged pieces. The intensity of structure development is influenced not only by the simple change of cross sections, but also by relative length of the stroke, magnitude of deformation in individual passes, manner of edging, temperature, friction and shape of anvils. The article gives an analysis of influence of the relative length of the stroke on the forging ratio. Comparison of grain size and mechanical properties on applied forging ration is presented in the article.
With using of the simulator HDS-20, the strength and plastic properties of two selected low-alloyed Cr-Mo steels, which were differing by carbon and manganese content, were experimentally investigated. By a special test consisting of loading of tested specimen by the small constant tensile force of 80 N in the whole course of his heating, the nil-strength temperature of the investigated steels was determined. The steel with the higher carbon content showed about of 42 °C lower nil-strength temperature. By uniaxial tensile tests to rupture which were performed in the range of deformation temperatures of 800 - 1410 °C at the constant tensile rate of 20 mm·s-1 and 1000 mm·s-1, the strength and plastic properties of the investigated steels were examined. The different carbon content did not significantly influence the strength properties of the investigated steels in the examined range of deformation temperatures. In the case of the hot ductility, similar results were obtained, but the steel with the higher carbon content showed about of 35 °C lower nil-ductility temperature. The difference between the nil-strength temperature and nil-ductility temperature was 39 °C and 32 °C in the case of the steel with the carbon content of 0.31 wt. % and 0.43 wt. %, respectively.
Today, more and more accent is in the automotive, aerospace and energy industries put on the use of materials with the specific utilize properties such as high strength and at the same time sufficient ductility to enable the production of given part. In addition to these key forming features, low weight and, last but not least, good corrosion resistance are also important. In view of the above requirements, titanium alloys appear to be a progressive construction material for the most demanding applications in a wide range of engineering production. This paper deals with the change of mechanical properties of titanium alloy with the trade name Grade 5 (Ti-CP 6Al-4V). The change of mechanical properties is evaluated by means of a static tensile test carried out in an insulated temperature chamber with resistance heating. The tests are carried out in the selected temperature interval, which should sufficiently represent changes in mechanical properties depending on temperature. Scanning and evaluation of the test deformation characteristics is performed by using an advanced contact-less optical deformation analysis method, which operates on the principles of the photogrammetry. Lab NET software and Mercury software are used for this purpose. The results of the measurements are dependencies of the titanium alloy mechanical properties on temperature within the selected temperature interval. Furthermore, the resulting temperature dependence of mechanical properties can be used as input material characteristics into the numerical simulation environment of the material forming process.
According to the concept of the Industry 4.0, all technological lines in the production plant are treated as the basic components of the superior system allowing for the optimization of the overall production process of the finished products. It is particularly important in the production plants with a high production automation factor. This article will present the aspect of optimization of the use of production equipment on the example of a technological line for cold processing of high-strength plates.
An important component in the considered technological line is a roller leveler, that allows the continuity of the production process. Optimization of this component allows you to achieve measurable benefits in the production of finished products. The universalization of the continuous straightening system has a decisive impact on the efficiency and productivity of the entire production process. The construction of the main device of the system, i.e. the roller leveler, should be maximally universal and provide a broad spectrum of geometries and strength properties of shaped batch plates. Therefore, a universal device should be considered in the field of the construction optimization and control method. However, the basic element should be the construction, because the process control rules remain unchanged. This article describes the method of making changes to unify and ensure the adjustment of the roller leveler structure to the needs of solving the assumed task. In addition, the quality and quantity requirements for the processed long semi-finished products, which determine the efficiency of production at the economically optimal level, have been taken into account.
The paper contains results of theoretical and experimental research on the bending process of tube with dimensions of 530 mm x 90 mm, used in production of power pipelines of X10CrWMoVNb9-2 steel grade. The innovative process of pipe bending with the use of local induction heating and results of its numerical simulation (FEM) were presented. Modelling of tube bending was done using Simufact Forming 12.0 software. A change of the geometry in the cross-section of the bend area was subjected to analysis, including the ovalization of the cross-section and the wall thickness in the region subject to tensile and compression. The geometrical features of the bend determined on the basis of numerical calculations were compared with the measurement results obtained in industrial conditions. Basic mechanical properties of the tube in the as-delivered condition and of the fabricated tube bend were determined using tensile, hardness, impact, low-cycle fatigue and creep tests. It was proved that the tube bends made of the X10CrWMoVNb9-2 steel, subject to bending using the proposed technology, meets the requirements of the applicable standards.
In the paper working conditions and requirements for cylinders of hydraulic actuators, used in mining roof supports to protect the roof of workings in underground coal mines are discussed. Significant functional effects that can be obtained by using the surface strain hardening of internal surfaces of cylinders of hydraulic actuators are indicated. A device designed for a dynamic method of percussive burnishing of internal cylinder surfaces with the use of a special hydraulic system is presented. The device enables an implementation of high-efficiency surface strain hardening. This treatment makes it possible to improve the resistance of cylinders to fatigue cracks and to harmful tribological phenomena resulting in a leakage of the working medium, affecting the environment negatively. An application of a strengthening device for cylinders enables a more favourable adjustment of hydraulic cylinders for use in extreme working conditions, in particular in the workings threatened by bumping hazards. Besides, the surface plastic deformation also serves to improve usage conditions of high-pressure sealing nodes and it reduces the leakage of water-in-oil emulsion.
The paper presents experimental results that concern hydroforming process axisymmetric components made from P265TR1 steel. The specimens used in investigations were segments of tubes having the outer diameter D = 22 mm and wall thickness s0 = 1 mm whose relative wall thickness was s0 / D = 0.045. The research on hydroforming of axisymmetric components was conducted at a stand which included ZD100 testing machine (1 MN force) equipped special tool with hydraulic feeding system. The machine was modified by LABORTECH firm (Czech Republic) and it is compliant with metrological requirements for
Class 1. Computer stand with Test&Motion software to measure forces and displacements was used. Axisymmetric components were hydroformed with upsetting ratios Dl / l0 = 0.075 and 0.09 (where Dl - the punch displacement, l0 - the initial length of tube). The paper gives the comparison of the microhardness distributions in different zones of longitudinal sections of axisymmetric components. The measurements of microhardness were taken with the Matsuzawa Seiki Co
Within the last year and for the first time worldwide, the innovative twin-roll casting process has been implemented for magnesium wire at the pilot plant at the Institute of Metal Forming of TU Bergakademie Freiberg. The aim of this study is to present a new process route via continuously twin-roll casting AZ31 magnesium alloy wires. Due to the combination of solidification and forming in one process step, in rolling direction deformed grains are present and precipitates are fine distributed. Remarkably, only a short heat treatment after twin-roll casting is necessary to dissolve segregations and to form equiaxed grains. Three states, namely twin-roll cast and two selected heat-treated, are characterized by means of microstructural investigations, texture investigations, tensile tests and hardness measurements.
Surface quality is one of the most important factors for steel strips in cold rolling mill. Steel strips are formed by extrusion in one direction, as a result, the mechanical properties will strengthen in one direction. Annealing heat treatment is applied to control and optimize the anisotropy. Sticky layers are very common in annealed strips and prevent achieving a smooth surface and in some cases, cause holes near the edges of strips, especially in final layers, that increases waste products. In this investigation, the methods that can reduce sticky layers were applied on ST22, ST24, and ST37 steel strips and could decrease waste products up to 70 %.
On the hot deformation simulator HDS-20 uniaxial compression tests of two nickel superalloys supplied in the molded state were performed. The cylindrical specimens were heated at rate of 10 °C·s-1 directly to the deformation temperature (i.e. from 880 °C to 1,240 °C with dwell time of 180 s after heating) and then were compressed at a constant strain rate of 0.1 s-1, 2 s-1 or 30 s-1 to a true strain of 1.0. Both materials exhibit a similar true stress-true strain curve with a relatively strong peak signalling the initiation of dynamic recrystallization. From the peak stress, the values of hot deformation activation energy were calculated, namely 483 kJ mol-1 for Inconel 600 and 601 kJ mol-1 for Incoloy 825. With the knowledge of these variables, equations describing peak stress could be derived for both superalloys (known sinus hyperbolic relation) with good accuracy. It corresponds to the peak strain (power dependence) depending on the Zener-Hollomon parameter, which represents the temperature-compensated strain rate. These dependencies and experimental data were mathematically and graphically compared for both materials. Peak stress is the amount appropriate for simple and fast prediction of the maximum flow stress due to the deformation parameters, excluding the effect of strain.
To evaluate formability in sheet metal forming, experimentally determined Forming Limit Curves (FLC) are often used. These conventional curves represent the forming limits of a material. The most widely used approach to experimentally determine the onset of necking of sheet metals is formulated in EN ISO 12004-2. The first goal of this work is to investigate limit strains for dual phase steel HCT490X with nominal thickness 0.6 mm. The second goal is to evaluate influence of strain rate on position of forming limit curve also for material HCT490X. The FLC curve has been measured through Nakajima test on universal testing machine. The test set-up and the shape of samples result from EN ISO 12004-2. Unrepeatable, isotropic and highly contrast pattern was applied on samples and was measured using 3D photogrammetric system ARAMIS by GOM. The punch movement velocity was gradually changed and experimentally measured forming limit curves are compared in this paper.
Biology-inspired algorithms represent a set of various techniques which can be used e.g. in the case of high-nonlinear approximation tasks. In the presented research, this kind of algorithms was utilized to approximate the experimental flow curve dataset of the micro-alloyed manganese-vanadium steel. Two methodically different representatives, namely a genetic algorithm optimization and an artificial neural network approach, were applied for this purpose. In the first case, a genetic-algorithm-optimization technique was used to calculate the material constants of two flow stress models. These models were then applied to describe the flow curves of the examined steel. In the second case, an artificial neural network was assembled, adapted and used to deal with the flow curve approximation issue. Graphical results have showed a high accuracy with respect to both approximation methods. Nevertheless, the following statistical evaluation has revealed a much higher fit in the case of the proposed neural network approach.
The paper presents the results of the investigation of the influence of the microalloying element niobium at the beginning of the plastic material flow in the cold drawing of the tubes.
Studies were conducted on low carbon steel and steel of the same base composition that was micro-alloyed with o, 46 % niobium. The steel strip of 370x3.00 mm is made of both steels.
Longitudinally welded tubes of 57 mm diameter and 3 mm wall thickness were made from the strip. Tubes were cold drawn to a diameter of 42 mm and wall thickness 2 mm. The tubes of both steels are cold drawing by the same parameters. The resulting results show different material behavior at the beginning of cold drawing. In the case of steel containing niobium at the beginning of cold deformation, Lüders bands appear. This phenomenon has not been noted for niobium-containing steel. Detailed structural tests have confirmed the appearance of Lüders bands in micro-alloyed steels. It has been found that niobium-containing steel occurs after non-homogeneous deformation after reaching the proportionality limit. Methods of thermography and digital image choleraeum confirmed that in the area of non-homogeneous deformations the appearance and propagation of Luders lines occurs. Only when it completes the propagation of the Lüders bands through the zone of deformation begins and the plastic deformation takes place. These changes have not been noted for niobium-containing steel.
In this study, hypoeutectic AlCu5 alloy and AlCu25 alloy in the as-cast condition were severely plastically deformed by extrusion combined with reversible torsion (KoBo) method to produce ultrafine grained structure. Scanning transmission electron microscopy (STEM), scanning electron microscopy (SEM) were used for microstructure characterization. Tensile test for characterization of mechanical properties were also performed. Tensile test were carried at room temperature and at temperature of 100 °C and 200 °C, with a speed of 10-4s-1. The results shows, that the KoBo deformation allows refinement of hypoeutectic structure. Tensile tests performed at room temperature revealed, that ultimate tensile strength (UTS) were 223 MPa and 366 MPa for AlCu5 alloy and AlCu25 alloy respectively. For AlCu5 alloy and AlCu25 alloy deformed at 200 °C, the UTS were 100 MPa and 182 MPa respectivelly. The elongation for failure (At) for AlCu5 alloy and AlCu25 alloy at room temperature were 18 % and 5 % respectively. For samples deformed at 200 °C, the At were 29 % and 40 % respectively.
The paper deals with the possibilities of the determination of the hot deformation activation energy and the flow stress course at hot forming conditions. By means of the Gleeble 3800 plastometer, the set of uniaxial compression tests has been carried out for the AISI 4140 steel. The tests were carried out within the temperature range of 850 - 1 250 °C and the strain rate range of 0.1 - 50 s-1 when the strain reached up to 1.0. From the obtained stress - strain curves the values of peak stress were determined and subsequently used to determine the value of the activation energy at hot forming according to the classical equation of the hyperbolic-sine type. Enumeration of its coefficients allow at the same time to predict the maximum flow-stress values of the investigated steel in dependence on the temperature and strain rate. The value of the activation energy has been used to assembly the mathematical models which allow to describe the flow stress course and the kinetics of the dynamic recrystallization of this steel at hot-forming conditions. By this way obtained results have been compared with the previously examined steel of the grade of AISI 4130.
Method DRECE (Dual Rolls Equal Channel Extrusion) belongs to a perspective group of technologies utilizing the process of severe plastic deformations (SPD). Used for forming of metallic materials. On the newly developed forming device, unlike the rolling technology, the material is significantly strengthening after the forming process, while maintaining the initial strip sheet dimensions. We want to achieve a significant increase in mechanical properties in as few passages as possible by the forming device, in particular increasing the yield strength Re and the ultimate tensile strength Rm, while maintaining good formability. The above-described forming method was used to extrude of low carbon steel. Overall, the effect of the individual passages on the increasing of mechanical properties of low carbon steel as tested in a total number of 1 to 7 passes through forming device. The forming tool, according to the pre-performed experiments, was chosen with an inclination of 108° in the deformation zone. The mechanical properties obtained after each pass through the forming device from the tensile tests and the influence of the anisotropy of steel on the mechanical properties were analyzed and the microstructure of the strip sheet was evaluated.
Alloys possessing a shape memory effect and mechanical characteristics similar to the behavior of living tissues are very useful as the material for production of medical devices, including implants, for example stents, without the need for additional devices except catheter-carrier. However, most of these alloys contain elements (including on its surface) which is toxic for organism. To satisfy the requirements of biochemical compatibility, the alloy should contain only safe elements as alloy components, which include: Ti, Nb, Ta, Zr. The possibility of obtaining of Ti-Nb-Ta-Zr thin wire was investigated. The structure was determined with the use of the optical microscope, X-ray diffractometer, scanning electron microscope (SEM) and Auger spectrometer. It was noted that a uniform structure was obtained for all compositions, before and after homogenizing annealing. The ingots have a dendritic structure. Niobium and zirconium were uniformly distributed throughout the sample, tantalum was concentrated in the dendrites themselves, titanium was predominantly in the regions between the dendritic axes, but is also found in it. X-ray diffractometry indicates that the elements of the alloy were not distributed in it by separate fragments, but were united in a single structure. The grain boundaries after plastic deformation and heat treatment were not identified in a microstructural analysis, which indicates that there was no recrystallization. It is possible that nanostructure was formed.
The assembling elements that were formed bimetallic billet in T-shape were chosen for lap joints creating of workpieces from thin sheets of metallic (Fe-Fe, Fe-Al) as well as metallic - nonmetallic (Fe-PMMA, Al-PMMA) materials by Resistance Element Welding method (REW). The tubes of Cu 99.9 with dimensions 4 mm x 0.5 mm and a length of 11 mm filled with a brazing solder Sn60Pb40 were used for the elements producing. The required shape of elements is obtaining by the cold solid forming. Simulation by ANSYS software code was chosen for optimization of forming process and functional parts geometry of forming tool allowing to use only one extrusion forming operation. The simulations results are stresses, strains and modification of cross-section geometry of billets for three proposed forming modes. The functional parts geometry of tool was compared with the results of cross-section macroanalysis of billets made by laboratory tools. Also, REW joints of selected material combination that were subjected to macroanalysis were presented.
Materials commonly used in various branches of the engineering industries are very often tested under basic conditions. This is due not only to the frequent effort to determine e.g. mechanical properties of the tested material just under reference conditions but also to the assumption that some material characteristics remain constant over the entire range of material loading conditions. In this paper, the change of Young's modulus in dependence on temperature is studied. Stainless steel was selected as the test material. To determine the required Young's modulus of elasticity, a static tensile test was performed on a testing machine equipped with a split tube furnace which allowed the desired loading temperature to be adjusted (generally from RT to about 1,400 °C). The force channel was thus detected by means of a load cell (using bridge strain-gauge circuit) clamped in a testing machine. Specimen extension was simultaneously monitored using the external Mercury contact-less optical system, where the actual distance between two monitored points was measured. The entire system thus functioned as a "virtual" strain-gauge delivering the necessary specimen extension channel. From these measured characteristics, the corresponding Young´s modulus of elasticity was finally calculated as a function of temperature. The resulting temperature influence on the values of Young´s modulus change not only gives a better insight into the deformation behaviour of the tested material in the elastic deformation area, but can be also used in the numerical simulations of deformation processes.
The article is focused on the process of severe plastic deformation (SPD). New method using the SPD principle (DRECE) is described in the article. New method using the severe plastic deformation (DRECE) is particularly suitable for forming metal materials. Materials produced by this technology are characterized by increasing mechanical properties when maintaining sufficient ductility of the materials. In the practical part of the work, experiments were carried out on DC01 steel using the DRECE method. Sheet metal strips were formed through one to seven passes through this device. The thickness of the formed strips was 2 mm, the strips width was 59 mm and the strips length were 1000 mm. The dimensions of the sheet metal strips were limited only by the design of the forming device using the method severe plastic deformation (DRECE). The experiment was performed on a forming tool with angle in the deformation material zone 108 °. The experiment was demonstrated on all sheet metal strips under the same forming conditions. The aim of the experiments was to verify the influence of the number of passes by the forming device on the achieved mechanical properties of the steel. The final part of the article describes the achieved mechanical properties of the sheet metal strip after forming by the DRECE method.
Currently, technological progress in many modern industries requires in implementation of new types of technical materials and related development of new manufacturing technologies that bring both enhancement of service properties of final products, as well as their wider implementation into engineering practice, including the associated energy savings. One possibility is also a constant increasing of consumption of non-ferrous metals. Sustainable development of human society is subject to a maximum economy of non-renewable sources of energy and raw materials, especially metallic ones. One of the ways for achieving this goal, in addition to recycling waste alloys based on aluminium, copper and magnesium, is systematic reduction of their consumption by increasing their quality and service life of utility objects and structures made from them. Already for many years, this happens in metallurgical production for example by alloying or by heat treatment. Production of reinforcing steel by cold deformation by twisting or by tension has brought Significant savings in civil engineering. In this way a significant increase of the yield point and its shifting to the ultimate strength was thus achieved at small decrease in ductility. Technical and economic benefits are obvious: metallurgical irreversible consumption of metals and of financial costs related to it were reduced at producers. One of the ways to the more effective use of metallic materials is their processing by forming. At present in this the area the use of the process of multiple severe plastic deformation (SPD process), leading to a refinement of the structure (materials with UFG structure) and thus to achievement of higher level of their utility value, is expanding.
Thanks to their specific features (such as corrosion resistance, resistance to high temperatures, good mechanical properties, unique physicochemical and aesthetic properties) stainless steels are practically applied in many areas, including construction and architecture, energy production, household appliances, automotive, food, chemical and pharmaceutical industries. Stainless steel products are usually manufactured from three basic steel grades: 301, 304, 314 or 316L, which are high in nickel content. The increase in the price of this raw material has led the stainless steel manufacturers to look for alternative steel grades whose use allows for a significant reduction in production costs while maintaining the same material properties. The aim of this study was to analyze the effect of cold drawing on the structure and properties of 204Cu steel. The tested grade belongs to the cost-effective group of stainless steels, and it can be used as a cheaper alternative to products with similar mechanical properties, while maintaining high corrosion resistance.
Regarding tool wear and energy consumption when forging steel parts, tailored preform geometries are beneficial. In particular, the number of forging steps can be reduced, in comparison to conventionally rolled cylindrical stock material, if preformed billets are used. In order to assess the potential offered by cast preforms as semi-finished products for a subsequent forging process, cylindrical steel billets (G42CrMo4) were cast by sand casting and then upset with different degrees of deformation φ (0.7-1.5), forging temperature (600-1200 °C) and ram speed (30-700 mm/s). Forging of conventional rolled bar material under the same forming conditions was used as a reference. After forming, the specimens were heat treated and the mechanical properties were determined by tensile tests (DIN EN ISO 6892-1) and notch impact tests (similar to DIN EN ISO 148-1). The microstructures were examined by metallographic analysis. For the investigated process variables, no significant influences on the tensile strengths or impact energies of the cast and forged specimens were found. While the tensile strengths of the cast and forged specimens meet the values of conventionally rolled and forged specimens, the impact energies of the cast and forged specimens surpass those of the reference. This is attributed to compressed pores, which were incompletely closed during forging. A criterion for the design of a die forging process of cast preforms will be derived based on the obtained results.
Due to stricter emissions standards of carbon dioxide production, automobile manufacturers are forced to search innovative solutions. An eventuality to reduce emission production is to reduce the weight of a car body. This weight reduction can be achieved by replacing material used in production of outer car body parts. The subject of this article is use of dual phase steel with tensile strength higher than 500 MPa for outer car body parts. Stampings used in experiment come from current models of ŠKODA AUTO, a.s. Due to lack of experience, material cards and feasibility of these parts were evaluated. Attention was paid primarily on crack initiation, wrinkling and springback.