MAG Process Research Articles

Iskustva u zavarivanju gasovoda "Turski tok" i interconector Srbija - Bugarska

The gas pipeline "Turski Tok" was built in the period from 2019 to 2021 with a total length of 403 km (Zaječar-Horgoš). The pipeline has a capacity of up to 15 billion cubic meters, a diameter of 1219 mm and its thickness is 14.27 mm. The steel L485MEPSL2 was used for production. The SerbiaBulgaria interconnector is 109 km long (Niš-Sofia), with a capacity of 1.8 billion cubic meters of gas, a diameter of 711 mm and the thickness is 8.7 mm. Steel X52 was used for its construction. Different procedures were used for welding: • Welding E-111 (cellulose and basic coating). • MAG 135 with welding of the root of the welded joint with a semi-automatic device STT, and filling with an automatic procedure with two devices. • Welding with the MAG process of the root of the welded joint on the inside, using the internal centralizer, and on the outside with the automatic MAG process with two devices. • Welding from the outside with automatic MAG process with two devices, Self-Shielded Flux Cored Arc Welding wire FCAW-114 using an internal centralizer with a copper ring. The paper presents experiences with gas pipeline welding, with a critical review of selected solutions and suggestions for optimizing welding technology.

Operational determination of current-voltage characteristics welding power sources in nuclear engineering

Welding equipment is everywhere equipped with modern digital welding arc power systems based on microprocessor and other logical element bases. At the same time, there is a tendency to minimize information not only for Chinese, but also for equipment of well-known brands, so it is important to quickly monitor the accuracy of the accompanying documentation in order to avoid deterioration in the quality of products and waste of time re-equipment. Modern recorders of welding processes allow several times to reduce the time for checking the declared characteristics of all power sources certified for use in the nuclear power industry. Among the characteristics and service functions analyzed by the recorder, it should be noted static current-voltage characteristics, oscillograms of «hot start», «afterburner» and «anti-sticking». The paper presents the data of selective tests for compliance with the declared passport data of inverter power supplies INEM-200T (MMA process), Artsen CM-500 (MAG process) and ION 48-900 (SAW process). Based on the results of the research, conclusions were drawn about the benefits of using the proposed model of the welding process recorder at enterprises of heavy nuclear engineering.

Influence of shielding gas variation and welding parameters on the microstructure and microhardness of SAE 1035 steel welded by the MAG process

The objective of this work was to evaluate the effect of changing the parameters of voltage, electric current and gases on the microstructure and microhardness of SAE 1035 steel. The welding process applied to the samples was the MILF STELL-MAG mode in the 4G position. The metallographic preparation was performed, following the ASTM E3 standard. The microstructural observations of each region of the welded joint were carried out in an optical microscope (THS – 200 Olympus) and for microhardness analysis a microhardness tester (HM-100 Mitutoyo) was used with a load of 1.0 kgf. ASTM E384 – 11 both carried out at the Science and Materials Engineering Laboratory of the State University of Amazonas (UEA). For sample 1, 170 ± 30A and 100% CO2 were used, for sample 2, 175 ± 30A and 100% CO2 were used, for sample 3, 180 ± 30A and 100% CO2 were used, for sample 4, 190 ± 30A and 100%CO2 and for sample 5 230 ± 30A and 100% Ar were used. By the microhardness analysis it was observed that there is an increase in the HAZ with the increase of the current using the CO2 gas. Welding using Argon gas showed a reduction in the microhardness of the HAZ. It is observed that there was an increase in the pearlite colony of the base metal close to the HAZ with the increase of the electric current. There was an increase in the HAZ with increasing electrical current.

UTILIZAÇÃO DA SOLDAGEM POR ARAME TUBULAR NO PROCESSO DE MANUFATURA MECÂNICA

With the ever-increasing competitiveness and the need to deliver products and services faster and with higher quality, the processes involving mechanical manufacturing are constantly developing, so welding has advanced in its technologies and procedures. This work aims to demonstrate that the use of the tubular wire welding process in mechanical manufacturing can be a good alternative for the gain of weld quality and productivity, clarifying the potential of the process, points that should gain more attention, and to other processes, it is hoped to increase the knowledge about welding, especially the tubular wire welding process, which has been gaining prominence in the last decades. By means of the review of available literature, the characteristics of the welding process using tubular wires, technology used, interferences that can occur in the welding, its consequences and the welding behavior by tubular wire in relation to such interferences are studied. In order to do so, the impact of the welding process on tubular wire in the welding quality and weld productivity gain was observed in the mechanical manufacturing, highlighting important points in the welding as a material deposition rate, comparing it with the MIG / MAG process and that its characteristics can bring of effective in front of the critical points of the welding. It was possible to verify that the process of welding by tubular wire brings benefits in several aspects as productive, economic and technical as well as important characteristics of application.

Tehnologija zavarivanja čeličnog liva G18CrMo4+QT sa konstrukcionim čelikom S355J2+N

Welding technology of cast steel G18CrMo4+QT with structural steel S355J2+N is a welding of dissimilar steels. The problem of welding cast iron G18CrMo4+QT is the phenomenon of hardening of the structure due to the presence of unreleased martensite, which results in lower toughness and the formation of cold cracks. On the other hand, structural steel S355J2+N, depending on the thickness of the material, is also prone to the appearance of cold cracks. In order to prevent the formation of cracks and eliminate residuals stresses, it is necessary to perform preheating and heat treatment after welding. The paper presents welding technologies and subsequent heat treatment of G18CrMo4+QT cast iron joint with S355J2 + N structural steel with presentation of test results performed on a 12 mm thick welded sample, with V preparation of the joint, welded by MAG process in PA welding position.

MAG shield gas influence study on impact strength of Al-5052 joint

Metal Active Gas Welding is a technique for efficiently combining many materials. Al-5052 was chosen for its non-corrosive, wear-resistant, anti-static, light weight, and formability qualities. Aluminium alloys are important in engineering and metallurgy because of their superior corrosion characteristics, ease of manufacturing, and high specific strength paired with the ideal balance of toughness and formability. The shape of the weld bead, mechanical properties, and distortion can all be utilised to assess the quality of a weld connection. Through solutioning and ageing, post-weld heat treatment improves weld quality, resulting in grain size refinement and better mechanical characteristics. MAG process utilized in ship, aerospace & marine construction. Determine the gas flow rate influence on impact strength of 5052 AL-Alloy joints size as 45x10x4 in mm. In this, 17.3 Joule impact strength obtained maximum at shielding gas flow of 7 Lt/min with constant current 235 amp.

Mechanical characterization of welded overlapped stainless steel by MAG process

Mechanical characterization of welded overlapped stainless steel by MAG process

Thermal evaluation of MAG/TIG welding using numerical extension tool

ABSTRACT The manufacturing processes involving thermal transitions have been more used in industries nowadays, being the welding one of the most widely used. The requirement to design and predict adverse conditions are fundamental to the development of any mechanical project. As a result, the market needs have motivated the companies to find faster and more effective solutions, being one of a recent tools an ACT (Ansys Customization Toolkit) called “Moving Heat Source”, in which is executed the Gaussian heat source to model welding and laser processes. Based on this, the present work proposes to evaluate the accuracy of that extension implementing a finite element model for the MAG/TIG welding processes in DINCK20 steel and Al6082-T6 aluminium alloy, comparing with one of the first mathematical model proposed by the literature (Rosenthal) and with a recent analytical method of high precision already validated experimentally. The results showed a smaller global error for MAG process (3~10%) when compared to TIG (15~18%) and, the temperatures measured on the surface of the plate presented errors lower than the bottom in both alloys.

Fracture toughness of MAG welds in pulsed current of API 5L AX65M thermomechanical treated steel

Abstract Prediction of unstable fractures or growth of existing cracks represents the fundamental problems in fracture mechanics. Experimental measurement of the propagation force of pre-cracks obtained by fatigue plays an important role in this prediction. The stress intensity factor at the crack tip (KIC), crack tip opening displacement (CTOD) and the crack tip opening angle (CTOA) are the most recognized parameters used in fracture mechanics [1]. This paper is focused on the determination of the fracture toughness, CTOD in the weld and the interface between heat affected zone/fusion line of the API 5L X65M steel pipe lines having a diameter of 42″ (1066.8 mm), a wall thickness of 31.75 mm, welded by the MAG process. To determine the crack tip opening displacement (CTOD), specimens subjected to bend in three-points (SENB = single edge notched bend) were used.

MAG welding of 960QL quenched and tempered steel

The article presents research of the welding technology of S960QL quenched and tempered steel with the thickness of 10 mm. The main problem during welding heat-treated fine-grained steels is cold cracking. The aim of the research was to develop welding technology of tested steel to obtain high ductility and strength properties of the joint and to avoid the problem of crack formation after welding process. For the test the butt joint was welded. For this it was used MAG process in the flat position. Welding process was carried out based on preliminary tests and pre-prepared Welding Procedure Specification according to ISO 15609-1 standard. During welding the M21 mixture was used as the shielding gas. As the filler metal a solid wire G Mn4Ni2.5CrMo was used. The welded joint was tested in accordance with the ISO 15614 standard requirements. The research included non-destructive tests and destructive tests. The non-destructive tests included visual, magnetic particle and radiographic tests. The destructive tests included transverse tensile, root and face bend, impact, macroscopic, microscopic and hardness. Impact test was carried out in the temperature of - 20°C. Hardness measurements were made using the Vickers method and the load of 9.80 N. All of the tests ended with the positive result. The results of research show that tested welding technology and pre-heating temperature equal to 80°C allow to obtain a welded joint meeting the high quality requirements and the international standards requirements.

Design review in Northern Ireland: the MAG process

ABSTRACTThis practice note examines the conduct of design review in Northern Ireland. Design Review has been conducted at the national level by the Ministerial Advisory Group, and the note explores the evolution of its practices and some of the challenges currently faced. Design review as a tool has proven to be an effective means to engage in and articulate a public perspective as part of the ongoing design conversation, but has not been high on the political agenda. A new push is required to raise awareness of the value of design and of design review to help secure it.

Fatigue behavior of MAG welds of thermo-mechanically processed 700MC ultra high strength steel

The present work analyzes the weldability of 8 mm thick plates of commercially available modern high strength steel with minimum yield strength of 700 MPa. The weldability is improved by modeling the welding conditions to evaluate and support the extensive analysis of the mechanical and the metallurgical properties of the welds. Materials were welded by a two-pass MAG process with four different heat inputs. All the welds and respective base materials underwent fatigue tests, tensile tests and hardness measurements. In tensile tests, the strains were measured using digital image correlation (DIC) equipment. Fatigue fracture surfaces were investigated for the highest and lowest loads tested using scanning electron microscopy. The failures in tensile and in fatigue tests occurred in the recrystallized HAZ. DIC measurements revealed that in tensile tests the strain localized in the domain of minimum hardness. The accumulative effect of both welding passes lowered the strength and hardness at the root side, making the root side more sensitive to weakening, as shown by hardness profiles. In addition, increasing the heat input lowered the fatigue strength of the welds. The welds had 150–300 MPa lower maximum fatigue strength (R = 0.1) than the base material.

MAG welding of S700MC steel used in transport means with the operation of low arc welding method

Manufacturers of welding equipment strive to develop the most efficient, cost-effective and easy to process welding methods. This necessity is also related to welding of new, often hard-to-weld steel types. The article aims to present the possibility of welding a high-strength S700MC steel with an increased yield point using MAG (135) process and a blowtorch with an intelligent arc control. The blowtorch allows to reduce input energy and reduce splinters while maintaining the mechanical properties of the material. The S700MC steel has been selected for the tests purposefully, as it may create welding problems in order to maintain high strength and increased yield point. The applied technology provided lower power consumption compared to traditional welding machines and joints with very good mechanical properties were achieved.

Research on the Use of Robotized Tandem MAG Welding in Steel Plates Destined for the Manufacture of Pipelines

The performed research focuses on the complete replacement of the pipeline manufacturing process consisting in welding on SAW+MIG / MAG generators with the robotized Tandem MIG / MAG welding procedure, with low energy consumption.The Tandem MAG procedure was experimented on X52 MS steel plates destined for the manufacture of pipelines, measuring 400x150x12 mm, with Y-joints (30o).The welded joints were executed horizontally and unilaterally, with flux bed support, 3 welding seams, using for filler material two wires of the same quality, EN ISO 14341: G 42 4 M G3Si1 (Filcord C), measuring 1.2 mm in diameter, and shielding gas EN ISO 14175 (CORGON 18).The entire technological welding process was carried out in fully robotized, laboratory conditions, using the QIROX -315 welding robot, fitted with Tandem MIG/MAG welding equipment, type QUINTO-GLC 603.The welding seams were executed with the same Tandem MAG welding head, with two wires, taking advantage of the possibility to rotate the welding head so as to obtain welding seams with the wires either positioned one after the other (tandem), or transversally (perpendicular to the welding direction), obtaining, by correlation with the welding speed, optimal linear energies, implicitly, seams of various widths and penetrations.The results of the tests concerning the characterization of the obtained welded joints corresponded to the mechanical – metallographic tests, falling within the ranges provided by the applicable standards.The welding parameters used in the robotized Tandem MAG procedure may lead to remarkable advantages concerning the use of energy and filler metal. Thus, linear energies are about 40% - 45% smaller than in the case of the classical SAW+MIG / MAG process, with positive effects on the mechanical and metallographic characteristics of the welded joints, leading to significant reductions in energy consumption. Furthermore, the use of filler materials (wire, shielding gas) decreases by 10% - 15% as compared to the classical SAW+MIG / MAG process, leading, implicitly, to lower costs.As a consequence of the obtained results, MAG Tandem welding procedure may become an alternative to SAW submerged arc welding and combined SAW and MIG / MAG welding and a classical reference method for the manufacture of pipelines

Relationship between penetration and porosity in horizontal fillet welding by a new process “hybrid tandem MAG welding process”

In the shipbuilding and bridge construction industries, shop primer paint is coated to the surface of steel plates in order to protect them from rusting during a long fabrication period. However, when arc welding is applied to the primer-coated plates, the arc heat may decompose and vaporize the coating. Then, the generated gas will be enclosed in the weld metal during the solidification process, causing the porosity defects, such as blowholes and the pits. In this study, the effects of penetration depth and non-penetrated joint root length on the generation of blowholes were clarified with various welding parameters. A new horizontal fillet welding process called ‘hybrid tandem MAG (HTM)’ was developed, a combination of a solid wire for the leading electrode and a flux-cored wire for the trailing electrode. The process features deep penetration and excellent porosity resistance. In order to reduce porosity in the fillet welding of primer-coated steel plate, it was found that the following measures are effective: (a) increasing the penetration depth and (b) decreasing the non-penetrated joint root length. The reduction of porosity by increasing the penetration depth is achieved by the formation of consistent ejection passage for vaporized gas. The phenomena mentioned above were verified by observing the interior of the weld pool directly by using an X-ray video camera. It is effective to reduce the leading electrode torch angle and to use a combination of high current and low voltage to create a buried arc to realize these measures. The MAG (HTM) procedure reduced the porosity formation to one tenth of that produced with the conventional tandem MAG process even at travel speeds up to 1600 mm/min.

Governing parameters affecting fume generation in short-circuit MAG welding

The operating parameters of the short-circuiting MAG process are expected to have a significant effect on fume generation. Despite this, no conclusive results on this subject have been presented in current literature. The objective of this work was to determine the most significant governing parameters affecting fume generation, by attempting to isolate each parameter from the others as much as possible. Several welding tests were carried out, and the effect of short-circuiting current, arc length (welding voltage), arcing time, and droplet diameters before detachment were investigated. The results show that the increase in each of these parameters contributes to a higher fume generation rate, and their effect becomes more significant when they act together.

A comparative study of fatigue behaviour of MAG and laser welded components using reliability analysis

Fatigue is one of the main causes of failure of structures and mechanical components, occurring due to the progressive weakening of their strength that reduces significantly their lifetime, when subjected to cyclic stresses over time. In welded components, the joints are the zones most susceptible to crack by fatigue.Therefore, the base of this study are the Metal Inert Gas/Metal Active Gas (MIG/MAG) and LASER welding manufacturing processes, focused in three main areas involved in an automotive metallic system under dynamic loads: Fatigue testing in order to prevent structural collapse; Heat Affected Zones (HAZ) characterization to evaluate the material properties modification originated by those different technologies; Reliability analysis in order to analyse the performance of the samples and to select the best connection in terms of product life cycle. For this purpose, samples representative of industrial automotive applications (long welds) have been selected to carry out this work. Two types of connected specimens were manufactured, consisting of two steel plates of different thicknesses, overlapping and welded by the MAG process (type A) or the Laser process (type B). Metallographic characterization was performed for both typologies, namely macrostructural and microstructural characterization of the weld joint, and respective HAZ. Mechanical properties were inferred by measuring and mapping microhardness variation on the neighbour of the weld joint. Fatigue tests were carried out for specimens type A and type B, using 15 samples of each type that were tested under 3 levels of stress amplitude. The samples manufactured by the Laser process show better fatigue behaviour when compared to the samples manufactured by MAG welding. The better weld joint solution is proposed in accordance with the reliability analysis of the obtained fatigue test results.

New High-Speed Fillet Welding by Twin Tandem Arc MAG Process

New High-Speed Fillet Welding by Twin Tandem Arc MAG Process

Study of formulations and the manufacturing variables of a ceramic weld backing

This paper presents a methodology for the in-lab manufacturing of a ceramic backing for the one-sided steel welds. Formulations were prepared using cordierite, bauxite, and magnesite as refractory minerals. Bentonite and sodium silicate were used as additives for the ceramic blend. The manufacturing process included dry mixture, compressing, drying, and sintering of the specimens. The weld backings were characterized by X-ray diffraction, optical microscopy of the surface, water absorption, and flexible voltage. They were also submitted to the welding of the root pass with the MIG–MAG process. The results show that the conventional ceramic manufacturing process is adequate for the production of the ceramic weld backing. Among the tested formulations, cordierite showed better integrity both during its manufacturing and during the welding operation, producing well-shaped weld beads, free from discontinuities. Manufacturing variables were evaluated such as compacting pressure, sintering temperature, and the amount of water added to the ceramic mass.

Residual Stresses in As-Welded Joints: Finite Element Modeling and Neutron Difraction Stress Measurements

This paper describes the numerical analysis method used to estimate welding induced residual stresses in K-shape tubular bridge joints. The knowledge of residual stress distribution is required to design the geometry of K-joints loaded under fatigue stresses. Numerical simulations are focused on the arc welding MAG process, generally used to weld joints in bridge construction. Thermo-mechanical analyses are performed in 3D using two finite element codes:ABAQUS® and MORFEO® . ABAQUS has the advantage to offer large analysis capabilities(nonlinear, transient, dynamic, etc.) whereas MORFEO is more dedicated to welding processes and offers the possibility to analyze crack propagation under fatigue loads. Computed residual stresses in the region surrounding the weld are compared with measured residual stresses in order to estimate the ability of the codes to reproduce these stresses. Position, orientation and magnitude of the highest residual stress components are discussed.