scholarly journals Laser Welding Of Finned Tubes Made Of Austenitic Steels

2015 ◽  
Vol 60 (3) ◽  
pp. 1807-1812
Author(s):  
M. Stolecki ◽  
H. Bijok ◽  
Ł. Kowal ◽  
J. Adamiec
Keyword(s):  
Laser Welding ◽  
Austenitic Steel ◽  
Technological Process ◽  
Welded Joints ◽  
Austenitic Steels ◽  
Tube Production ◽  
High Quality ◽  
Manufacturing Costs ◽  
Finned Tubes

Abstract This paper describes the technology of welding of finned tubes made of the X5CrNi1810 (1.4301) austenitic steel, developed at Energoinstal SA, allowing one to get high quality joints that meet the requirements of the classification societies (PN-EN 15614), and at the same time to significantly reduce the manufacturing costs. The authors described an automatic technological line equipped with a Trumph disc laser and a tube production technological process. To assess the quality of the joints, one performed metallographic examinations, hardness measurements and a technological attempt to rupture the fin. Analysis of the results proved that the laser-welded finned tubes were performed correctly and that the welded joints had shown no imperfections.

Research of Technology for Repair of Heat Exchangers of Nuclear Power Plants by Laser Welding

2021 ◽  
Vol 313 ◽  
pp. 94-105
Author(s):  
A. Bernatskyi ◽  
V. Sydorets ◽  
O.M. Berdnikova ◽  
I. Krivtsun ◽  
O. Kushnarova
Keyword(s):  
Service Life ◽  
Laser Welding ◽  
Welded Joints ◽  
Heat Exchangers ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Mechanical Test ◽  
Austenitic Steels ◽  
Depth Of Penetration

Extending the lifetime of energy facilities is extremely important today. This is especially true of nuclear power plants, the closure (or modernization) of which poses enormous financial and environmental problems. High-quality repair of reactors can significantly extend their service life. One of the critical parts is heat exchangers, the tubes of which quite often fail. Sealing, as a type of repair of heat exchanger tubes by the plugs, is promising provided that the joint quality is high. Practical experience in the use of welding to solve this problem has shown the need to search technological solutions associated with increasing the depth of penetration and reducing the area of thermal effect. The aim of the work was to develop a highly efficient technology for repair and extension of service life of heat exchangers of nuclear power plants based on the results of studying the technological features of laser welding of joints of dissimilar austenitic steels AISI 321 and AISI 316Ti in the vertical spatial position. Based on the results of the analysis of mechanical test data, visual and radiographic control, impermeability tests and metallographic studies of welded joints, the appropriate modes of laser welding of plugs have been determined. The principal causes of defects during laser welding of annular welded joints of dissimilar stainless steels are determined and techniques for their elimination and prevention of their formation are proposed. Based on the results of the research, technological recommendations for laser welding of plugs in the heat exchange tube of the collector are formulated, which significantly improves the technology of repair of steam generators of nuclear power plants and extends the service life of reactors.

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.

Using of Welding Virtual Numerical Simulation as the Technical Support for Industry

2016 ◽  
Vol 1138 ◽  
pp. 49-55
Author(s):  
Marek Slováček ◽  
Josef Tejc ◽  
Mojmír Vaněk
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Welded Joints ◽  
Welding Process ◽  
Austenitic Steels ◽  
Welding Parameters ◽  
Efficient Production ◽  
Weld Joints ◽  
Mechanical Properties Prediction

Welding as a modern, highly efficient production technology found its position in almost all industries. At the same time the demands on the quality of the welded joints have been constantly growing in all production areas. Great demand on the quality of the welded joints consequently causes more experimental or prototype – so called – validation joints that take place before the welding of final construction. These experiments, prototypes aim at – for instance – defining the appropriate welding technology, material, pre-heating, welding parameters, clamping condition and optimizing the welding process. Naturally, these experiments and prototypes make production more expensive. Numerical simulations of welding – in the area of production preparation as well as of production proper – have been frequently used recently. Numerical simulations supported by experimental measurements can simulate the actual welding process very close to reality. The new material models for hardness and mechanical properties prediction based on numerical simulation solution will be introduced.The paper covers some typical welding cases from energy industrial sector. The homogenous and heterogeneous weld joints from modern energy Cr-Mo-Ni-V steels (including modern austenitic steels) were done as prototype welding. The numerical simulation of these weld joints including post weld heat treatment process were done and welding technologies were optimised based on the numerical simulation results. The calculated hardness was compared with real measurements. During project the complete material properties which are needed for numerical simulation were measured. Simplify numerical lifetime prediction of weld joints including results from numerical welding analyse (as residual stresses and plastic deformation) were done.

scholarly journals Research of technical and technological operations of irrigation and development of initial requirements to the technical means of their realization

2021 ◽  
Author(s):  
V. M. Мaliarchuk ◽  
◽  
A. O. Migalev ◽  
V. V. Sidorenko ◽  
E. M. Fedorchuk
Keyword(s):  
Technological Process ◽  
Irrigated Agriculture ◽  
Modern State ◽  
Separate Component ◽  
High Quality ◽  
Irrigation Methods ◽  
Ecological Requirements ◽  
Irrigation Purpose ◽  
Quality Indexes

Authors as a result of researches got informative, statistical and experimental data which allowed to ground and form initial requirements on the machine technological operations of irrigation. Purpose of researches – to conduct the analysis of practice of application of multi-supporting sprinkling-machines which are used in technologies of the irrigated agriculture, define the high-quality indexes of implementation of technological process and construction features for forming of requirements on the technical and technological operations of irrigation. Methods of researches: empiric, measuring, theoretical, mathematical and statistical, analysis of existent normative base. Results of researches. In the process of researches prospects, problems and terms of application of multi-supporting sprinkling-machines, are analyzed, the modern state and tendencies of improvement of these machines are considered. The brought classification over and structural signs of sprinkling-machines, basic charts and methods of irrigation, the review of constructions of sprinkling machines and technological features of their application, certain high-quality and operating-technological indexes of work of machines, are given. An operating in Ukraine normative base is analyzed in relation to requirements to the broad-cut sprinkling-machines at their application in the technique and technology operations of irrigation. It is educed as a result of analysis, that an investigational normative base touches mainly requirements to the construction of sprinkling machines and their separate component parts, methods of tests and requirements of safety. General initial requirements on technical and technological operations of irrigation, which touch quality of implementation of technological process, operating-technological and ecological requirements, requirements to reliability of and other absent. On the basis of the conducted researches and tests, experimental and informative data, which were taken as base, certain and initial requirements are reasonable on the technique and technology operations of irrigation at the use of broad-cut multisupporting sprinkling-machines, were got. Conclusions: the necessity of application of sprinkling-machines is set taking into account ecological requirements and the basic rules of their use are certain with the purpose of warning of erosive processes of soils .initial requirements are Certain and reasonable on the technical and technological operations of irrigation at the use of broad-cut multi-supporting sprinkling machines.

Evaluation of Influence of Thermal Methods of Metal Separation Cutting on Welding Quality

2017 ◽  
Vol 265 ◽  
pp. 755-761 ◽  
Author(s):  
A.K. Tingaev ◽  
M.A. Ivanov ◽  
A.M. Ulanov
Keyword(s):  
Heat Affected Zone ◽  
Welded Joints ◽  
Heat Input ◽  
Experimental Studies ◽  
Welding Process ◽  
Regulatory Requirements ◽  
High Quality ◽  
Thermal Methods ◽  
Welding Seam

We have investigated a possibility of obtaining high-quality welded joints after oxygen and plasma cutting of steel С355 without removing the heat-affected zone (HAZ), in which the changes in chemical, phase and structural compositions are observed. Numerical and experimental studies of the effect of heat input of MAG and Submerged Arc welding on the quality of welded joints are performed. In particular, it was found that when the heat input of welding is at least 6.5 kJ/cm, the metal of HAZ of the edges after cutting is heated during the welding to temperatures above Ас3, which leads to its full recrystallization. When the heat input of welding is at least 10 kJ/cm, the edges after cutting are completely melted and become a part of the welding seam metal. The presence of extensive areas of melting and recrystallization of the edges in the welding process contributes to obtaining high-quality welded joints without removing the HAZ of the edges after cutting. To verify the results of numerical studies, experimental tests of control welded joints were conducted, which showed that the values of bending angle and impact toughness of the welding seam metal and heat affected zone are significantly above the regulatory requirements to quality of welded joints, and not less than the same requirements for steel С355. The obtained results confirm the possibility of revising domestic regulatory requirements for the steel constructions production in terms of the preparation of edges for welding using technologies of thermal cutting without subsequent machining.

scholarly journals Improving the Quality of Welded Joints in Laser Welding of Silver Products

2019 ◽  
Vol 8 (9S3) ◽  
pp. 102-104
Keyword(s):  
Laser Welding ◽  
Welded Joints ◽  
Experimental Studies ◽  
Pulsed Laser ◽  
Welding Process ◽  
Pulsed Laser Welding

The article deals with promising areas of application of pulsed laser welding for products made of silver-based alloys. The results of experimental studies on the choice of modes of pumping, defocusing to improve the quality of the weld and the efficiency of the welding process.

Analysis of Quality of Welded Joints of Iron-Concrete Products

2019 ◽  
Vol 942 ◽  
pp. 121-130 ◽  
Author(s):  
Ludmila Redko ◽  
Inna Plotnikova ◽  
Nataliya Chicherina ◽  
Olga Tchaikovskaja ◽  
Josefa Bastida
Keyword(s):  
Economic Development ◽  
Life Cycle ◽  
Statistical Methods ◽  
Welded Joints ◽  
Failure Modes ◽  
Welding Process ◽  
Negative Effects ◽  
High Quality ◽  
Welded Structures

The search for effective methods of management is one of the strategic directions of economic development. To obtain high-quality products, organizations should manage nonconformities and causes of product defects. The paper focuses on the analysis of groups of defects of welded joints using statistical methods. Welding process was considered as one of the processes of management. The possible causes of nonconformities were indicated. The method of failure modes and effects analysis was used to quantify the level of risk. A matrix of consequences and probabilities was presented, and critical risks and risk situations were selected. The proposed measures to eliminate or minimize negative effects enable identification of problem areas of the life cycle of welded structures.

Features of Laser Welding Light Constructions from Cryogenic Austenitic Steel 316L

2019 ◽  
Vol 822 ◽  
pp. 512-519 ◽  
Author(s):  
M. Kuznetsov ◽  
Maksim Larin ◽  
Alexander Sorokin
Keyword(s):  
Laser Welding ◽  
Austenitic Steel ◽  
Welded Joint ◽  
Light Metal ◽  
Metal Structures ◽  
The Real ◽  
316L Steel ◽  
Real Objects

The publication describes the results of the research of the influence of laser welding mode parameters on geometry and quality of the formation of the welded joint of 316L steel with thickness of 1 mm. According to the results of research in the framework of pre-project works, in order to test the technology at the real objects, components of light metal structures were welded.

scholarly journals Features of Acoustic Emission in Tensile Testing of Dissimilar Welded Joints of Pearlitic and Austenitic Steels

2021 ◽  
Vol 11 (24) ◽  
pp. 11892
Author(s):  
Vera Barat ◽  
Artem Marchenkov ◽  
Vladimir Bardakov ◽  
Marina Karpova ◽  
Daria Zhgut ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Austenitic Steel ◽  
Welded Joints ◽  
Pearlitic Steel ◽  
Structural Heterogeneity ◽  
Austenitic Steels ◽  
Data Registration ◽  
Welding Defects ◽  
Complex Decision ◽  
Characteristic Features

This paper presents a study of acoustic emission (AE) during the deformation of dissimilar welded joints of austenitic steel to pearlitic steel. One of the specific problems in these welded joints is the presence of decarburized and carbide diffusion interlayers, which intensively increase in width during long-term high-temperature operation. The presence of wide interlayers negatively affects the mechanical properties of welded joints. Moreover, welded defects are difficult to diagnose in welded joints containing interlayers: due to the high structural heterogeneity, interlayers create structural noises that can hinder the detection of defects such as cracks, pores, or a lack of penetration. The AE method may become a complex decision for diagnosing dissimilar welded joints due to applicability to the testing of heterogenic materials with a complex microstructure. Specimens cut from dissimilar welded joints of austenitic steel to pearlitic steel were tested by tension to rupture, with parallel AE data registration. According to the research results, the characteristic features of the AE were revealed for specimens containing defects in the form of lack of penetration as well as for specimens with diffusion interlayers. The results obtained show that the AE method can be used to test both typical welding defects and diffusion interlayers in welded joints of steels of different structural classes.

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