IDENTIFICATION OF THE INFLUENCE OF THE SPATIAL ORIENTATION OF THE DEPOSITED LAYERS, AS WELL AS THEIR OVERLAP COEFFICIENT ON THE SURFACE SHAPE ERROR DURING ADDITIVE SHAPING BY AN ELECTRIC ARC

Статья посвящена изучению вопросов управления процессом аддитивного формообразования изделий. Представлены результаты исследования процесса аддитивного формообразования поверхности электрической дугой в среде защитного газа. Проведен анализ погрешности формы поверхностей, полученных с различным заполнением слоев. Подтверждено экспериментально, что такие параметры процесса, как ориентация слоев, коэффициент их перекрытия являются значимыми. Так, погрешность формообразования образцов наплавки слой на слой в вертикальном направлении выше по сравнению с другими способами наплавки, реализованными в эксперименте. Средние значения погрешности формы образцов составляют 0,75 мм, 0,88 мм, 1,15 мм, соответственно, для способов наплавки слой к слою на горизонтальную поверхность с коэффициентом перекрытия 0,3, слой к слою на горизонтальную поверхность с коэффициентом перекрытия 0,5, слой на слой в вертикальном направлении. Максимальные значения погрешности определены на уровне 0,85 мм, 1,2 мм, 1,5 мм для соответствующих способов наплавки, реализованных в эксперименте. Таким образом, пространственная ориентация слоев, а также коэффициент перекрытия слоев являются значимыми, оказывают влияние на численное значение погрешности формы получаемой поверхности, должны быть учтены при проектировании алгоритмов разделения на слои, их заполнения при аддитивном формообразовании электрической дугой в среде защитного газа The article is devoted to the study of the issues of managing the process of additive shaping of products. The paper presents the results of a study of the process of additive surface shaping by an electric arc in a protective gas medium. We analyzed the error of the shape of the surfaces obtained with different filling layers. We confirmed experimentally that such process parameters as the orientation of the layers, their overlap coefficient are significant. Thus, the error of forming samples of surfacing layer on layer in the vertical direction is higher compared to other methods of surfacing implemented in the experiment. The average values of the sample shape error are 0.75 mm, 0.88 mm, 1.15 mm, respectively, for methods of surfacing layer to layer on a horizontal surface with an overlap coefficient of 0.3, layer to layer on a horizontal surface with an overlap coefficient of 0.5, layer to layer in the vertical direction. The maximum error values are determined at the level of 0.85 mm, 1.2 mm, 1.5 mm for the corresponding surfacing methods implemented in the experiment. Thus, the spatial orientation of the layers, as well as the overlap coefficient of the layers, are significant, affect the numerical value of the shape error of the resulting surface, should be taken into account when designing algorithms for dividing into layers, filling them with additive shaping by an electric arc in a protective gas medium

Simulation of an Electric Arc in Metal Welding

This paper describes the proces of electric arc welding in the zone of protective gas, with an emphasis on transmitting metal dropelts via a short ciruit.Parameters of the welding proces and of an electric arc are described, and a mathemacal model for the MIG system is sugessted. Model simulation is completed used Matlab/Simulink package. The proces is simulated using real parameters in order for the output values of the process to corespond to real values obtained by the means of mesasurement.

Effect of Y addition on the structural transformation and thermal stability of Ti-22Al-25Nb alloy produced by mechanical alloying

In this study, a Ti-22Al-25Nb alloy with nanocrystalline structure was produced by high energy mechanical alloying (HEMA) and 1 at.-% yttrium was added as a thermal stabilizer. The as-milled samples were annealed at various temperatures up to 900 °C in a protective gas atmosphere, and the samples were allowed to cool to room temperature in the furnace. The phase transformations and microstructural changes as a function of the annealing temperatures and alloy compositions were studied using room- and high-temperature X-ray diffraction (XRD), focused ion beam microscopy (FIB), and scanning electron microscopy (SEM). The mechanical properties of the samples were interpreted based on the hardness results and their correlation with the microstructures. The results showed that the as-milled nanocrystalline structure of Ti-22Al-25Nb alloy increased from 3.4 nm to 350 nm after annealing at 800 °C due to the high driving force induced by the large grain boundary area. Consequently, the as-milled hardness of the Ti-22Al-25Nb alloy dropped from 7.63 ± 0.18 GPa to 5.37 ± 0.28 GPa. The grain size stability of the Ti-22Al-25Nb alloy after annealing at elevated temperature was ensured through the addition of yttrium. Thus, the grain size remained at the level of 125 nm, and the hardness value was maintained at around 6.98 ± 0.43 GPa after annealing at 800 °C.

ISIM Contributions to the Development of Friction Welding Procedures

During the last 15 years, the friction stir welding process (FSW) and the techniques developed based on the FSW principle have been a main research direction within ISIM Timisoara. The paper summarizes activities and results obtained by the FSW research team within the institute. The paper presents a synthesis that aims a briefly presentation of its own achievements and contributions from recent years regarding the development of the FSW process, especially on the following directions:- Friction stir welding on couples of similar and dissimilar materials;- Use of FSW-TIG (friction stir welding – tungsten inert gas assisted) and FSW-US hybrid processes friction stir welding - ultrasonic assisted);- Friction stir welding in protective gas environment;- Friction stir welding equipment and tools;- Systems for monitoring of the welding process. Results obtained at friction stir butt welding or by overlapping of some couples of materials that are difficult or impossible to be joined using conventional welding procedures, were presented. The results obtained during these years, as well as their scientific and technical level, have allowed the proposal for implementation of solutions that involve FSW welding for specific industrial applications (especially for the automotive field).

Some Peculiarities of MIG-MAG Welding Processes with Concentrated Energies

Throughout the history of modernization of welding processes, in many cases the research has focused on optimizing the location of energy in the welding area, with the continuous improvement of the quality of welded joints. The welding processes in shielding gas environment with fusible electrode (MIG-MAG) have achieved superior performances regarding the increase of the current density around of the welded joint, simultaneously with the increase of the universality degree of their application. This paper is based on researching the possibilities of concentrating energy in the welding area, seeking to obtain both more favorable energy yields and an increased quality of welded joints. In the paper are shown a some results obtained following a comparative study on 2 welding processes in MIG-MAG protective gas medium, differentiated mainly by the metal drop transfer mode: by spraying (Spray arc), respectively by synergistic transfer (Arc pulsed), applied for corner welding of alloy steel sheets.

The Design and Manufacturing Process of an Electrolyte-Free Liquid Metal Frequency-Reconfigurable Antenna

This communication provides an integrated process route of smelting gallium-based liquid metal (GBLM) in a high vacuum, and injecting GBLM into the antenna channel in high-pressure protective gas, which avoids the oxidation of GBLM during smelting and filling. Then, a frequency-reconfigurable antenna, utilizing the thermal expansion characteristic of GBLM, is proposed. To drive GBLM into an air-proof space, the thermal expansion characteristics of GBLM are required. The dimensions of the radiating element of the liquid metal antenna can be adjusted at different temperatures, resulting in the reconfigurability of the operating frequency. To validate the proposed concept, an L-band antenna prototype was fabricated and measured. Experimental results demonstrate that the GBLM in the antenna was well filled, and the GBLM was not oxidized. Due to the GBLM being in an air-proof channel, the designed liquid metal antenna without electrolytes could be used in an air environment for a long time. The antenna is able to achieve an effective bandwidth of over 1.25–2.00 GHz between 25 °C and 100 °C. The maximum radiation efficiency and gain in the tunable range are 94% and 2.9 dBi, respectively. The designed antenna also provides a new approach to the fabrication of a temperature sensor that detects temperature in some situations that are challenging for conventional temperature sensing technology.

Study on the burn-out of Ti and Al elements in the electroslag refining process

In this paper the burn-out of the alloying elements Ti, Al in the electroslag refining was studied. The experiment was conducted on laboratory scale electroslag refining (ERS) equipment, the steel grades used in the study contain Ti and Al alloy elements. Experimental results showed that the burn-out ratio of Ti and Al in ESR was quite high. To minimize that ratio, it was possible to apply technological measures such as: using protective gas and selecting of an appropriate slag system, as well as combining additives containing Ti and Al for slag in the refining process. When applying these measures, the burning level of Ti and Al has decreased significantly compared to the previous one (from > 50 % to below 20 %). Especially in case of using the ANF-32 slag + 10 % TiO2 and conducting the operation of ESR under the Ar gas environment, the burn-out ratio of these alloy elements exhibited a negative value.