scholarly journals Development of physical models for calculating thermal fields in wet underwater welding

2021 ◽  
pp. 60-63
Author(s):  
В.В. Мурзин ◽  
К.М. Сое
Keyword(s):  
Base Metal ◽  
Welded Joint ◽  
Thermal State ◽  
Heat Content ◽  
Decisive Role ◽  
Heat Fluxes ◽  
Physical Models ◽  
Depth Of Penetration ◽  
Underwater Welding ◽  
The Impact

В статье рассматривается влияние на развитие технологии мокрой подводной сварки использование методов математического моделирования значительно облегчает исследование тепловых потоков, что позволяет рассчитать скорость охлаждения металла в опасном диапазоне температур (800-500оС) и определить свойства металла сварного соединения. Определяющую роль в сварке играет теплообмен, который формирует протекание физико-химических, диффузионных, гидродинамических процессов. Форма сварочной ванны, а значит, объем и теплосодержание характеризуется ее длиной, шириной, толщиной и глубиной проплавления основного металла. Сварочная ванна ограничивается изотермической поверхностью, имеющей температуру плавления основного металла. Предполагается, что на свойства сварного соединения влияет только энергия, поступающая в основной металл. В известных физических образах и математических моделях теплового процесса сварки и наплавки не рассматривается, какое влияние на околошовную зону оказывают потоки теплоты от объема (массы) металла сварочной ванны, хотя в некоторых моделях изучается влияние скрытой теплоты плавления на тепловое состояние основного металла. The article discusses the impact on the development of wet underwater welding technology the use of mathematical modeling methods significantly facilitates the study of heat flows, which allows us to calculate the cooling rate of the metal in the dangerous temperature range (800-500oC) and determine the properties of the metal of the welded joint. The decisive role in welding is played by heat transfer, which forms the flow of physico-chemical, diffusion, and hydrodynamic processes. The shape of the weld pool, and hence the volume and heat content, is characterized by its length, width, thickness, and depth of penetration of the base metal. The welding bath is limited to an isothermal surface having a melting point of the base metal. It is assumed that the properties of the welded joint are affected only by the energy entering the base metal. In the known physical images and mathematical models of the thermal process of welding and surfacing, it is not considered what effect the heat fluxes from the volume (mass) have on the near-seam zone) the effect of the latent heat of melting on the thermal state of the base metal is studied in some models.

scholarly journals Microstructure and Impact Toughness of Local-Dry Keyhole Tungsten Inert Gas Welded Joints

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1638 ◽  
Author(s):  
Shuwan Cui ◽  
Zhiyong Xian ◽  
Yonghua Shi ◽  
Baoyi Liao ◽  
Tao Zhu
Keyword(s):  
Impact Toughness ◽  
Weld Metal ◽  
Welded Joint ◽  
Coincidence Site Lattice ◽  
Random Phase ◽  
Inert Gas ◽  
Phase Boundaries ◽  
Site Lattice ◽  
Underwater Welding ◽  
The Impact

In this paper, the microstructure and impact toughness of a S32101 duplex stainless steel underwater local-dry keyhole tungsten inert gas welded joint were studied. The impact toughness value of the underwater weld metal reached 78% of the onshore weld metal, which is in accordance with the underwater welding standards. The proportion of austenite in the underwater weld metal was 0.9% lower than that of the onshore weld metal. The proportion of the Σ3 coincidence site lattice boundaries and random phase boundaries in the underwater weld metal, which significantly influence the impact toughness of the weld metal, were smaller than that of the onshore weld metal.

scholarly journals БЕЗКОНТАКТНЕ ЕЛЕКТРОЖИВЛЕННЯ ІМПЛАНТАТІВ

2019 ◽  
pp. 30-39
Author(s):  
Володимир Петрович Олійник ◽  
Дар’я Вікторівна Теличко
Keyword(s):  
Magnetic Field ◽  
Human Body ◽  
Power Supply ◽  
Energy Supply ◽  
Thermal State ◽  
The Body ◽  
Alternating Magnetic Field ◽  
Artificial Organs ◽  
Depth Of Penetration ◽  
The Impact

The issues of long-term implants using in the human body are considered. Particular attention is paid to the problem of contactless supply of power to artificial organs with significant energy consumption. Using non-contact energy supply to a fully implanted technical device reduces the risk of infections getting into the patient's body as compared to the use of a power line that is output through internal tissues to the skin surface. The well-known developments of artificial heart apparatus were used as the object of analysis. Their main technical characteristics are considered. The maximum power consumption of these devices is about 20 watts, including models AbioCor. The design of the AbioCor was produced as a fully implanted contactless power unit, but the project was not completed. Although the principle of contactless power supply is undoubtedly an innovative step in the development of implant designs. As a result of the technical implementation of this principle, the following was obtained: it is advisable to use an alternating magnetic field with an inductive coupling between an external and an internal inductor for non-contact energy supply of implants; the use of frequencies of an alternating magnetic field of ~ 100 kHz makes it possible to obtain a compromise solution between the required depth of penetration into biotissues, insignificant heat formation in them and the size and mass of inductors. Under such conditions, the location in the body of the receiving inductor can be determined by medical recommendations. Evaluation experiments were carried out to determine the effective scheme of inclusion of the transmitting and receiving circuits, and the effect on the transmission coefficient of the electrophysical properties of the environment between them. It is shown that for working out of technical solutions of hardware realization of contactless power supply, implantation elements can be placed in saline solution as a model of bioenvironment. It is recommended to use serial element base and circuit solutions used for contactless power supply of radio electronic devices. Also, a quantitative assessment of the additional heat load of the implant on the human body was carried out, since part of the energy of the apparatus and its work, in accordance with the efficiency, inevitably goes into the heat eventually. A simplified calculation of the impact of implant energy losses on the thermal state of the body showed that overheating by 1 °C would be achieved provided the complete insulation of the area, on average, 8.6 hours. This proves the non-critical overheating of the body with implants, and allows the maintenance of a stable body temperature by physiological mechanisms.

scholarly journals Comparative physiological and hygienic assessment of the personal protective equipment EP-4(0) in the various assembly according to human thermal state indices

2021 ◽  
Vol 100 (3) ◽  
pp. 229-233
Author(s):  
Olga V. Burmistrova ◽  
Sergey Yu. Perov ◽  
Tatyana A. Konshina
Keyword(s):  
Heart Rate ◽  
Body Temperature ◽  
Air Temperature ◽  
Personal Protective Equipment ◽  
Thermal State ◽  
Heat Content ◽  
Operating Conditions ◽  
The Body ◽  
Protective Equipment ◽  
The Impact

Introduction. The article presents results of the study of the impact of the personal protective equipment EP-4 (0) in various assembly (overalls, jacket and trousers, jacket and semi-overall) from power frequency electric field and electrical shock on the thermal state of workers in a heating environment at air temperature 34.8 ○C and relative humidity 48%. Materials and methods. The study involved three men aged 35.3±4.6 years. They did the physical exercise for 40 minutes, had comfortable relaxation for 30 minutes after work. Recorded indices included skin temperature and moisture sensation score on 11 parts of the body, body temperature in the ear canal, heart rate, clothes temperature, heat sensation score, moisture loss, moisture evaporation efficiency. Results. Overalls using had the highest values of heat content, moisture score, heart rate changes, and body temperature increment. Heat content index in the body reached maximum permissible value using overalls earlier than other configurations. Conclusion. The research data showed overalls have the most significant impact on the human thermal state, jacket and trousers have the least impact, jacket and semi-overall take an intermediate place. The configuration including jacket and trousers, jacket and semi-overall under specific operating conditions is the most optimal. Such PPE assembly can be recommended for use in the open area in the summer season at an air temperature of 35 ○C and above, subject to protective requirements.

Microstructures and Mechanical Properties on Laser Welded Joints of Automotive High Strength Complex Phase Steel

2010 ◽  
Vol 97-101 ◽  
pp. 3957-3962
Author(s):  
Lian Hai Hu ◽  
Qi Yan ◽  
Jian Huang ◽  
Yi Xiong Wu
Keyword(s):  
Mechanical Properties ◽  
Laser Welding ◽  
Fusion Zone ◽  
Base Metal ◽  
Automobile Industry ◽  
Welded Joint ◽  
High Strength ◽  
Uniaxial Tensile ◽  
Complex Phase ◽  
The Impact

Reducing car’s weight has become an important goal for automobile industry. Laser welding of automotive high-strength steel plays a significant role in producing light weight cars. Experiments of CO2 high power laser welding of 1000MPa grade complex phase steels with a thickness of 3mm for automobile were performed using a 15 KW CO2 laser. The macrostructure and microstructure of the welded joint were examined by optical microscope. Mechanical properties of the welded joint, fusion zone and base metal were assessed by microhardness distribution across the welded joint, uniaxial tensile test and charpy V-notch impact test. Fractographs of the impact specimens were studied by scanning electron microscopy (SEM). It is found that the fusion zone has a higher toughness than that of the base metal and fusion line. The test results show good mechanical properties of laser welds that can meet the technical requirements for automobile Industry.

Effects of particulate reinforcements on the hardness, impact and tensile strengths of AA 6061-T6 friction stir weldments

2021 ◽  
pp. 146442072199554
Author(s):  
TE Abioye ◽  
H Zuhailawati ◽  
AS Anasyida ◽  
SP Ayodeji ◽  
PK Oke
Keyword(s):  
Tensile Strength ◽  
Impact Strength ◽  
Base Metal ◽  
Welded Joint ◽  
High Hardness ◽  
Friction Stir ◽  
Heat Treated ◽  
Impact Energies ◽  
The Impact ◽  
Metal Hardness

Due to loss of structural strengthening at temperatures beyond 250°C, heat-treated aluminium alloys (e.g. AA 6061-T6) weldments are usually characterized with poor mechanical properties including hardness, tensile and impact strengths. In this work, friction stir weldments of AA 6061-T6 reinforced with the additions of SiC, B4C and Al2O3 particles at the joints were produced and investigated for improved hardness, tensile strength and impact strength over the unreinforced weldment. The results showed that the entire reinforced welded joint exhibited improved hardness because of the enhanced metal matrix grain refinement and inherent high hardness of the reinforcement particles. B4C particle addition produced hardest joint of about 81% of the base metal hardness (∼114 HV0.3). The impact energies of the SiC (16.9 J), B4C (16.5) and Al2O3 (12.2 J) reinforced weldments are closer to that of the base metal (18.6 J) compared with the unreinforced weldment (9.6 J). The reinforced weldments showed no significant improvement over the tensile strength of the unreinforced weldment. B4C and SiC reinforcements produced the highest improvements in the hardness (at the joint) and impact strength of the AA 6061-T6 friction stir weldments, respectively.

scholarly journals Influence of Long-Term High-Temperature Action on the Impact Toughness of the Base Metal and the Weld Metal of the 22K Steel Welded Joint

2021 ◽  
Vol 51 (7) ◽  
pp. 428-437
Author(s):  
S. A. Nikulin ◽  
S. O. Rogachev ◽  
V. A. Belov ◽  
A. A. Komissarov ◽  
V. Yu. Turilina ◽  
...  
Keyword(s):  
High Temperature ◽  
Impact Toughness ◽  
Weld Metal ◽  
Base Metal ◽  
Welded Joint ◽  
Temperature Action ◽  
The Impact

Расчетные методы оценки ударной вязкости сварных элементов с трещинами

2020 ◽  
Vol 44 (3) ◽  
pp. 22-36
Author(s):  
Keyword(s):  
Stress Intensity ◽  
Impact Strength ◽  
Welded Joints ◽  
Development Process ◽  
Welded Joint ◽  
Operating Temperature ◽  
Crack Development ◽  
Heterogeneous Structure ◽  
Critical Crack Length ◽  
The Impact

Практика показывает, что для сварных конструкций, эксплуатируемых в условиях Крайнего Севера необходимо уделять внимание работоспособности сварных соединений при низких температурах. Металл сварных соединений в процессе воздействия обработки изменяет свои свойства, снижается ударная вязкость, образуется гетерогенная структура с большой степенью разнозернистости. Чтобы оценивать и иметь возможность правильно контролировать термическое воздействие и последствия сварочного процесса, требуется решить задачу аналитического определения ударной вязкости для всех зон сварного соединения. В настоящей статье представлен инженерный метод оценки ударной вязкости, применимый для любой зоны сварного соединения, в которой имеется острый или особый концентратор напряжений – трещина. Разработанный аналитический метод расчета ударной вязкости отражает качественную и количественную картину взаимосвязи структурно-механических характеристик и работы развития трещины в диапазоне температур 77…300 К. Предложенная схематизация зависимости критического коэффициента интенсивности напряжений от температуры позволила найти коэффициенты, характеризующие свойства материала, и выполнить расчеты изменения предела текучести и предела прочности от температуры эксплуатации. Построены графики зависимости работы развития трещины от температуры эксплуатации для сталей 15ГС и 17ГС, сравнение которых с экспериментальными данными показывает удовлетворительное согласование. Найдено, что при напряжениях предела выносливости отношение работы развития трещины к критической длине трещины постоянно, не зависит от температуры и для сталей 15ГС и 17ГС равно около 10. Ключевые слова: ударная вязкость, работа разрушения, коэффициент интенсивности напряжений, трещина, феррито-перлитная сталь, зона термического влияния. For welded structures under operation in the Far North, attention must be paid to the performance of welded joints at low temperatures. The properties of metal of welded joints are changed in the process of treatment, its toughness decreases, and a heterogeneous structure with a large range of different grain sizes is formed. In order to evaluate and be able to correctly control the thermal effect and the consequences of the welding process, it is necessary to solve the problem of analytical determination of impact strength for all zones of the welded joint. The paper presents an engineering method for evaluation of the impact strength applicable to any area of the welded joint in which there is a sharp or super sharp stress concentrator – a crack. The developed analytical method for calculating the impact strength reflects a qualitative and quantitative codependency of structural and mechanical characteristics and the process of crack development in the temperature range of 77–300 K. The proposed schematization of dependence of the critical coefficient of stress intensity on the temperature made it possible to find coefficients characterizing the properties of the material and to perform calculations of changes in yield strength and tensile strength on operating temperature. Graphs of the crack development process dependency on the operating temperature for 15ГС and 17ГС steels were constructed, and their comparison with experimental data displays satisfactory agreement. It was found that at endurance limit stresses, the ratio of the crack development process to the critical crack length is constant, non-dependent on temperature, and is equal to 10 for 15ГС and 17ГС steels. Keywords: impact strength, fracture work, stress intensity factor, crack, ferrite-pearlite steel, heat affected zone, steel tempering.

Peculiarities of tool material wear at polymeric composite blank cutting

2018 ◽  
Vol 2018 (7) ◽  
pp. 27-31
Author(s):  
Юрий Зубарев ◽  
Yuriy Zubarev ◽  
Александр Приемышев ◽  
Alexsandr Priyomyshev
Keyword(s):  
Tool Wear ◽  
Tool Material ◽  
Polymeric Composite ◽  
Physical Models ◽  
Technological Parameters ◽  
Tool Materials ◽  
Materials Used ◽  
The Impact ◽  
Material Wear

Tool materials used for polymeric composite blank machining, kinds of tool material wear arising at machining these blanks, and also the impact of technological parameters upon tool wear are considered. The obtained results allow estimating the potentialities of physical models at polymeric composite blanks cutting.

scholarly journals Process Modeling and Simulation of Tableting—An Agent-Based Simulation Methodology for Direct Compression

Pharmaceutics ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 996
Author(s):  
Niels Lasse Martin ◽  
Ann Kathrin Schomberg ◽  
Jan Henrik Finke ◽  
Tim Gyung-min Abraham ◽  
Arno Kwade ◽  
...  
Keyword(s):  
Raw Materials ◽  
Pilot Scale ◽  
Physical Models ◽  
Agent Based Simulation ◽  
Validation Data ◽  
Agent Based ◽  
Industrial Processing ◽  
Digital Twins ◽  
Product And Process ◽  
The Impact

In pharmaceutical manufacturing, the utmost aim is reliably producing high quality products. Simulation approaches allow virtual experiments of processes in the planning phase and the implementation of digital twins in operation. The industrial processing of active pharmaceutical ingredients (APIs) into tablets requires the combination of discrete and continuous sub-processes with complex interdependencies regarding the material structures and characteristics. The API and excipients are mixed, granulated if required, and subsequently tableted. Thereby, the structure as well as the properties of the intermediate and final product are influenced by the raw materials, the parametrized processes and environmental conditions, which are subject to certain fluctuations. In this study, for the first time, an agent-based simulation model is presented, which enables the prediction, tracking, and tracing of resulting structures and properties of the intermediates of an industrial tableting process. Therefore, the methodology for the identification and development of product and process agents in an agent-based simulation is shown. Implemented physical models describe the impact of process parameters on material structures. The tablet production with a pilot scale rotary press is experimentally characterized to provide calibration and validation data. Finally, the simulation results, predicting the final structures, are compared to the experimental data.

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