scholarly journals An Analysis of the Quality of the Thick-Walled S355J2+N Steel Joint Welded by the Mag Method

2017 ◽  
Vol 62 (2) ◽  
pp. 833-839 ◽  
Author(s):  
R. Krawczyk
Keyword(s):  
Mechanical Strength ◽  
Welded Joints ◽  
Welded Joint ◽  
Strength Properties ◽  
Butt Joints ◽  
Steel Joint ◽  
Welding Method

AbstractAn analysis of the quality of the thick-walled S355J2+N steel welded joint used most frequently in the general-building, power and other contemporary steel constructions is presented in the following article. A process of examining welding technologies was made on the tick-walled butt joints of plates by using the MAG – 135 welding method. The aim of the discussed topic was to optimize the process of welding thick-walled welded joints due to their mechanical strength properties and efficiency.

scholarly journals Influence of welding method on microstructural creation of welded joints  

2011 ◽  
Vol 57 (Special Issue) ◽  
pp. S50-S56 ◽  
Author(s):  
P. Čičo ◽  
D. Kalincová ◽  
M. Kotus
Keyword(s):  
Welded Joints ◽  
Arc Welding ◽  
Welded Joint ◽  
Gas Metal Arc Welding ◽  
Structural Phase ◽  
Welding Parameters ◽  
Welding Method ◽  
Welding Technology ◽  
Metal Arc Welding

This paper is focused on the analysis of the welding technology influence on the microstructure production and quality of the welded joint. Steel of class STN 41 1375 was selected for the experiment, the samples were welded by arc welding including two methods: a manual one by coated electrode and gas metal arc welding method. Macro and microstructural analyses of the experimental welded joints confirmed that the welding parameters affected the welded joint structure in terms of the grain size and character of the structural phase.

Features of the Heating Process in Ultrasonic Welding of Polycarbonate Products under Independent Pressure

2020 ◽  
pp. 54-62
Author(s):  
S.S. Volkov ◽  
A.L. Remizov ◽  
A.S. Pankratov
Keyword(s):  
Welded Joints ◽  
Welded Joint ◽  
Welding Process ◽  
Ultrasonic Welding ◽  
Heating Process ◽  
Mechanism Of Formation ◽  
High Quality ◽  
Acoustic Contact ◽  
Welding Pressure

This paper presents a mechanism of formation of a hard-to-weld polycarbonate joint by ultrasonic welding. The method utilizes internal and external friction occurring in the welded joint area on abutting surfaces due to shear vibrations of the end of the upper part relative to the lower part. A layer of the heated welded material is formed, localized by thickness, in which predominant absorption of the ultrasonic vibrations occurs, which allows one to obtain high-quality and durable welded joints without significant deformation due to the concentration of thermal energy in the welding zone. The effect of independent welding pressure on the strength of the welded joint of polycarbonate is considered. A new method of ultrasonic welding under the conditions of independent pressure is proposed. The method consists of dividing the static welding pressure into two components: the pressure of the acoustic contact in the zone of contact of the waveguide with the product, and the welding pressure that compresses the welded products, with the latter component being lower than the former. In order to obtain high-quality welded joints made of polycarbonate and to prevent displacement of the welded edges during the welding process relative to each other, a special preparation of the welded edges is developed, which allows one part to be moved vertically relative to the other during the welding process. It is established that the quality of welding depends on the speed of movement and the angle of cutting the edges.

A Study of the Influence of Electron Beam Welding Defects on Fracture Processes in Titanium Alloys

2020 ◽  
pp. 23-34
Author(s):  
V.V. Grigoriev ◽  
V.I. Muravyev ◽  
P.V. Bakhmatov
Keyword(s):  
Electron Beam ◽  
Titanium Alloys ◽  
Welded Joints ◽  
Pore Formation ◽  
Electron Beam Welding ◽  
Strength Properties ◽  
Technical Documentation ◽  
Welding Defects ◽  
Static And Dynamic Loads

The appearance of pores when welding titanium has been extensively studied by domestic and foreign researchers, but there has been no consensus on the causes and conditions of pore formation to date. An overview of advances in the studies of pore formation showed that the problem of formation of the macropores, reaching 0.1 mm was investigated by A.A. Erokhin, V.V. Frolov, G.D. Nikiforov, S.M. Gurevich, V.N. Locks, V.I. Muravyev, B.I. Dolotov, P.V. Bakhmatov et al. The advent of modern x-ray machines in the technological control of permanent joints made by electron beam welding has enabled researchers to detect a specific defect — the so-called dark bands, which make it difficult to assess the quality of permanent connections due to the absence of this defect in the normative and technical documentation. Determining the causes of specific defects and their effect on the properties of titanium alloy structures made by electron beam welding is an important task. This paper presents the results of studies investigating the effect of specific defects of electron beam welding of titanium alloys VT20, VT23 on the nature of destruction under static and dynamic loads and changes in the mechanical properties of the welded joints. It is established that specific defects occurred during electron beam welding have a significant impact on the strength properties of welded joints, as well as on the stages of their destruction. It is determined that the presence of such welding defects as lack of penetration, residual stresses and pores in the fusion zone, expulsion without bonding, etc. contribute to the formation of sub-micropores that lead to brittle destruction of welded joints. The presence of specific defects in permanent joints made by electron beam welding leads to decreased strength properties and to nearly complete absence of such characteristics as elongation and contraction. It is established that heat treatment improves the quality of welded joints.

Characteristics of Fusion-Welded Joints Made Using Martensitic Steel after 100,000 Hours in Service

2016 ◽  
Vol 246 ◽  
pp. 177-182
Author(s):  
Adam Hernas ◽  
Adrian Mościcki ◽  
Roman Krupa
Keyword(s):  
Welded Joints ◽  
Martensitic Steel ◽  
Welding Process ◽  
Fusion Welding ◽  
Tube Material ◽  
Butt Joints ◽  
National Centre ◽  
Fusion Welded Joints

The paper presents the results of tests of mixed fusion-welded joints consisting of superheater pipes of grades T91 and HCM12A(T122) after 100,000 hours in service in a BB-1150 boiler welded to new pipes (in “as-delivered” condition) of grades T91 and VM12-SHC. The state of the microstructure and properties of the used tube material after long term service are characterized. The paper describes fusion welding conditions and parameters, and evaluates the quality of the created butt joints. The results of tests of the macro-and microstructure of the joints and their mechanical properties are presented. It was determined that the welding process intensifies further degradation of the tested materials to a small extent only. This work was performed under the Strategic Research Project No SP/E/1/67484/10 supported by the National Centre for Research and Development.

Study of wear resistance of railway rails welded joint

2020 ◽  
Vol 76 (8) ◽  
pp. 818-825
Author(s):  
N. A. Kozyrev ◽  
R. A. Shevchenko ◽  
A. A. Usol'tsev ◽  
R. E. Kryukov ◽  
A. R. Mikhno
Keyword(s):  
Wear Resistance ◽  
Thermal Treatment ◽  
Base Metal ◽  
Heat Affected Zone ◽  
Welded Joints ◽  
Welded Joint ◽  
Welding Method ◽  
Welded Seam ◽  
Short Time ◽  
Metal Hardness

Welding joints of rails are a weak point of a jointless railway line, which stipulates actuality of studies on increasing their operational resistance. Microstructures of welded joints made by existing at present welding technology and by a new one were compared. Existing (base) technology comprises further thermal treatment of the welded joint, while the new technology comprises welding followed by a short-time electric current impact during the rail joint cooling. To study the microstructures of welded joints, samples were cut out the welded seam zone and heat affected zone, as well as out of the base metal. The study was carried out in the depth of 5 mm from the surface, after thin section etching by 4% solution of nitric acid in alcohol. In the macro-structure of the metal of welded joint, made by the base technology, an uneven heat affected zone was detected. The zone had the following dimensions: 51 mm – in the head, from 45 mm to 62 mm – in the neck and 64 mm – in the bottom (by each of the seal side). In the longitudinal mac- ro-template of sample Б (the new welding method), the heat affected zone was even and along the whole joint had the width of 22 mm (in each of the joint side). It was shown, that the new welding method of railway rails enables to decrease the extension of zone with sorbitic and granular pearlite at various stage of coagulation. A short-time impact of electric current during rail joint cooling ensures obtaining a zone with a decreased hardness of 15 mm extension and decrease of welded seam metal hardness relatively the lower border of base metal hardness by less than 15%. Application an additional local thermal treatment by a separate induction heating during base technology results in forming zones of 30 mm extension in the area of welded joint, which wear resistance is 4.5 times lower comparing with wear resistance of the rail base metal. At the new welding method application, the extension of the abovementioned zone does not exceed 10 mm and wear resistance was decreased by less than 2 times.

scholarly journals The impact of deformation in the zone of welded joints on the force action of the rolling stock on the track

2020 ◽  
Vol 79 (1) ◽  
pp. 9-16
Author(s):  
V. S. Kossov ◽  
O. G. Krasnov ◽  
M. G. Akashev
Keyword(s):  
Welded Joints ◽  
Welded Joint ◽  
Experimental Studies ◽  
Longitudinal Direction ◽  
Local Heat ◽  
Rolling Stock ◽  
Rolling Surface ◽  
Kolmogorov Smirnov ◽  
The Impact

The causes of deformation in the zone of welded joints are considered. Authors experimentally studied changes in hardness on the rolling surface of the rail in the longitudinal and transverse profiles within the thermally affected zone of the welded joint. It is established that the hardness of the rolling surface of the rail in the longitudinal direction in the thermally affected zone of the joint is uneven and is determined by the structures arising from the effects of the thermal cycles of welding and the quality of the local heat treatment. In this case, two "low spots" are clearly traced with a decrease in hardness to 290...300 HB and with a higher hardness up to 350 HB right in the welded joint. Experimentally investigated the change in the depth of the welded joint from the implemented tonnage. At the same time with strain gauge method, using the force method developed by N. N. Kudryavtsev, continuous changes in vertical forces when the wheels move along the welded joint zone were recorded. Average values of vertical forces from loaded cars were established. Experimental distributions of vertical forces were approximated by theoretical laws according to the Kolmogorov — Smirnov matching criterion. Recommendations are given on minimizing the harmful impact of rolling stock on the track in areas of lowering welded joints.The following conclusions were made.1.            Geometry of the joint irregularity is in the form of a W-shaped deformation with an influx of metal on the receiving rail and lowering on the directing rail. The width of the upper part of the deformation varies between 160...200 mm along the axis of the rail.2.            Deformation zone of the welded joint is a source of increased dynamic impact from the wheels of the rolling stock on the elements of the upper track structure. According to the results of experimental studies it was found that the greatest increase in dynamic effects was observed from locomotive wheels up to 45..               . 70 kN, maximum values reached 180...210 kN, from the wheels of loaded freight cars the values of vertical forces increased by 35..     .45 kN, maximum values reached 145...170 kN, from the wheels of empty cars increase dynamic impacts amounted to 14...16 kN, maximum values reached 32...36 kN.

A Study of the Possibility of Reducing Residual Stresses and Strains in Welded Joints by Ultrasonic Treatment

2020 ◽  
pp. 3-10
Author(s):  
S.S. Volkov ◽  
A.V. Konovalov ◽  
L.A. Shestel
Keyword(s):  
Residual Stresses ◽  
Welded Joints ◽  
Ultrasonic Treatment ◽  
Welded Joint ◽  
Joint Zone ◽  
Degree Of Deformation ◽  
Processing Modes ◽  
Steel Grades ◽  
Residual Stresses And Strains

This work explores the possibility of using ultrasonic vibrations as a method for eliminating residual and intrinsic stresses, as well as improving the quality of welded joints. Based on the experiments carried out on three steel grades of various classes, it was found that ultrasonic treatment of welds contributed to the elimination of such defects as deformations, intrinsic and residual stresses, as well as increasing fatigue strength and certain mechanical properties of welded joints. An analysis of existing methods of removing residual and intrinsic stresses was conducted. It was shown that the treatment of the welded joint zone by ultrasound reduced the degree of deformation over time by more than two times. A method for determining stresses in welded joints was developed. Ultrasonic processing modes were optimized to determine the energy and power in the welded zone. The shape and the material of the waveguide tool with a spherical percussion mechanism were selected.

Some Peculiarities of MIG-MAG Welding Processes with Concentrated Energies

2021 ◽  
Vol 890 ◽  
pp. 3-8
Author(s):  
Voicu Ioan Safta ◽  
Dumitru Mnerie ◽  
Gabriela Victoria Mnerie
Keyword(s):  
Welded Joints ◽  
Welded Joint ◽  
Metal Drop ◽  
Transfer Mode ◽  
Steel Sheets ◽  
History Of ◽  
Protective Gas ◽  
Welding Processes ◽  
Gas Medium

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.

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.

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