Active Gas Welding Research Articles

Influence of the Pulse Mode of Manual Metal Arc Welding on Weldment Distortions.

As a result of the thermo-mechanical impact during welding, distortions are generated in welded structures. These distortions significantly influence the geometric and dimensional accuracy of welded structures, in many cases lowering their working characteristics and reliability. An optimal design for welded structures is a prerequisite for increased reliability and reduction in manufacturing cost, and such an optimal design can be achieved knowing the distortions in weldments. Despite the fact that pulsed metal inert gas welding and metal active gas welding have been broadly applied in the last few decades, nowadays, few manufacturers, for instance, Fronius, EWM, Redco, and Perfect Power Welders, offer such an option for manual arc welding. This work aims to determine the influence of the parameters of pulsed welding modes on distortions that are generated during manual arc welding. Two different inverter welding power sources were used, and the welding distortions were measured by 3D scanning. The results showed that the pulsed mode during manual arc welding led to a reduction in distortions compared to the conventional welding mode. The crucial part of the manual welding system proved to be the qualification and performance of the welder.

Research on the Influence of HMFI and PWHT Treatments on the Properties and Stress States of MAG-Welded S690QL Steel Joints.

The aim of this study was to analyze the effect of the HFMI (high-frequency mechanical impact) treatment of each weld bead on the properties of a butt joint with a ceramic backing welded by robotic method 135 (MAG-metal active gas welding method) and to determine the effect of HMFI on the stress level. This analysis was based on a comparison of three butt joints made of a S690QL plate, in the as-welded condition, with the HFMI of each bead and with the heat treatment carried out with PWHT stress relief annealing. The high-frequency (90 Hz) peening of each weld bead was linked with a stress reduction in the weld via the implementation of compressive stresses into the joint. The HFMI pneumatic hammer was used for this. The correctness of treatment was achieved when 100% of the surface of each bead including the face was treated. As part of the post-welding tests, basic tests were carried out based on the standards for the qualification of welding technology, and as a supplementary test, a stress state analysis using the Barkhausen effect was carried out. The tests carried out showed that the use of high-frequency peening after each pass did not affect the negative results of all the required tests when qualifying the welding technology of S690QL sheet metal compared to the test plates in the as-welded condition and after heat treatment-stress relief annealing. Inter-pass peening of the welded face and HAZ (heat-affected zone) resulted in a reduction in post-weld residual stresses at a distance of 12 mm from the joint axis compared to the stress measurement result for the sample in the as-welded condition. This allowed for a positive assessment of peening in the context of reducing the notch, which is the concentration of tensile stresses in the area of the fusion line and HAZ. The tests carried out showed that the peening process does not reduce the strength properties of welded joints, and the results obtained allow the technology to be qualified based on applicable standards.

Microstructure, Mechanical Properties, and Wear Behavior of Dissimilar Metallic Coatings for Steel Discs of Butterfly Valves

Abstract In the present work, coating materials that can be welded to the EN 1.6220 low-alloy steel disc of a butterfly valve and are also compatible with the seal material, i.e., 17–4 PH steel, are studied. 312 duplex stainless steel, 316 austenitic stainless steel, and Stellite 6 are identified as potential coating materials for the disc based on Cobweb analysis and are welded to the disc using metal active gas (MAG) welding (312 and 316 steel coatings) and powder plasma arc welding (Stellite 6 coating). Microstructural analyses and Vickers hardness measurements of the weld joints are performed. The surface roughness and wear behavior of the coatings are also studied. Nanoscale wear phenomena and consequent phase transformations are studied using molecular dynamics simulations. The results show that 312 and 316 stainless steels are suitable coating materials for the disc.

Source Apportionment of Particulate Matter in a Metal Workshop.

Metal workshops are workplaces with the substantial production of particulate matter (PM) with high metal content, which poses a significant health risk to workers. The PM produced by different metal processing techniques differs considerably in its elemental composition and size distribution and therefore poses different health risks. In some previous studies, the pollution sources were isolated under controlled conditions, while, in this study, we present a valuable alternative to characterize the pollution sources that can be applied to real working environments. Fine PM was sampled in five units (partially specializing in different techniques) of the same workshop. A total of 53 samples were collected with a temporal resolution of 30 min and 1 h. The mass concentrations were determined gravimetrically, and the elemental analysis, in which the concentrations of 14 elements were determined, was carried out using the X-ray fluorescence technique. Five sources of pollution were identified: background, steel grinding, metal active gas welding, tungsten inert gas welding, and machining. The sources were identified by positive matrix factorization, a statistical method for source apportionment. The identified sources corresponded well with the work activities in the workshop and with the actual sources described in previous studies. It is shown that positive matrix factorization can be a valuable tool for the identification and characterization of indoor sources.

EXPERIMENTAL STUDY ON MAG WELDED E350 HSLA STEEL JOINTS

Activated flux has been used successfully to improve the penetration of Tungsten Inert-Gas (TIG) welding, which is normally a welding process with low penetration. But the same activated flux when used for Metal Active Gas (MAG) welding showed a moderate improvement in penetration. Hence only a few research articles reported on activated flux MAG welding. TIG dressing is a post-weld treatment intended to improve the fatigue life of welded joints. The use of activated flux along with TIG dressing were not yet reported. In this work, an experimental study was conducted on the metallurgical changes and their effects on fatigue life in E350 steel welded by MAG welding with activated flux coating as well as toe TIG dressing. The metallurgical changes induced by various weld conditions and the effect on the fatigue life of welded joints were discussed. Welding conditions were categorised as: as weld (AW), weld with flux coating (FW), weld with TIG dressing (AWT), and flux weld with TIG dressing (FWT). Fatigue tests at stress ranges closer to the yield stress (80 % to 90 % of yield) were studied. In comparison with AW joints, the AWT and FWT showed a fatigue-life improvement of 60 % to 80 %, and 69 % to 103 % respectively. Whereas the FW joints showed 10 % to 17 % deterioration in fatigue life. Upon investigation with electron microscopy it was found that the variation in grain sizes and phase changes induced by the usage of flux and TIG dressing, as well as the changes in weld toe radius by TIG dressing and root strengthening due to extra penetration induced by the use of flux were the reasons behind these fatigue behaviours. In this work a novel effort is made to find a way to improve the fatigue life of a welded joint with a combination of two techniques. The activated flux is used to improve the penetration, whereas TIG dressing is performed to reduce the stress concentration. This new combination of techniques has improved the fatigue life of the weld significantly, which can lead to reduced maintenance costs of welded joints and a longer life.

Welding of S1100 Ultra high‐Strength Steel Plates with Matching Metal‐Cored Filler Wire: Microstructure, Residual Stresses, and Mechanical Properties

This study investigates the relationship between the microstructure and the mechanical properties and the residual stresses of thermomechanically rolled, butt‐welded S1100MC ultra high‐strength steel plates. Matching metal‐cored filler wires are used for metal active gas welding of the plates in horizontal and vertical‐up positions. The effect of the heat input on the microstructures of both the weld metal (WM) and the heat‐affected zone (HAZ) is studied in detail. The microstructure of the WM consists of different types of ferrite, but the microstructure of the HAZ predominantly consists of fresh martensite at the top and bottom areas. Structure and size of the prior austenite grain boundaries are dependent on the welding positions and affect the impact toughness of the welds. HAZ of the weld produced in vertical‐up position is under intensive tensile residual stresses next to the fusion line. Even with matching filler wires, the strength of the welds is insufficient, and fracture of the weld metal occurs because the extended cooling time leads to the formation of acicular ferrite instead of martensite.

Experimental Investigation of Welding Parameters On Mild Steel Using Metal Active Gas Welding

Gas shielded welding is a widely applied fabrication processes in manufacturing industry. The present study will elucidate on an investigative approach to find the mechanical properties, influenced by several input parameters like welding current, voltage and wire spool speed in the Metal Active Gas Welding (MAG) of Mild Steel. Taguchi’s L9 orthogonal array has been employed to analyse the process parameters. The levels of consequences of input parameters were investigated by applying analysis of variance (ANOVA). The microstructural orientations and mechanical properties of weld specimen are explored in this work. Welding current is an influential parameter to control tensile strength followed by welding voltage and federate of electrode. Furthermore, hardness of weld material has a greater effect of voltage including wire speed and current.

Design and analysis of robot and fixture pedestal for OTC FD-V8 MAG welding robot

The use of automation in the welding process is favoured due to its capacity to enhance the welding quality and expedite the completion of the task. Welding is a commonly automated process in assembly lines, with many companies relying on robotic welding due to its efficient nature. The key advantages of an automated welding process include higher-quality welds, increased productivity, reduced waste production, and lower labour costs. Gas Metal Arc Welding (GMAW) is of two types: namely, Metal Inert Gas (MIG) welding or Metal Active Gas (MAG) welding. GMAW is a welding process that involves a welding gun through which a wire electrode and a shielding gas are fed continuously. This process is commonly performed using a direct current power source with constant voltage, but other types of power sources can also be used. GMAW offers four primary methods of metal transfer, namely globular, short-circuiting, spray, and pulsed-spray, each of which has its unique properties and benefits as well as limitations. In this study, the OTC FD-V8 model robot is used for welding. The pedestal for the robot is designed using SOLIDWORKS and the static analysis of the robot pedestal is done. The fixture is used to hold the work piece for welding. The quality of the weld bead is determined by parameters like voltage, welding current, wire diameter, and composition of the shielding gas.

Investigating the Detection Capability of Acoustic Emission Monitoring to Identify Imperfections Produced by the Metal Active Gas (MAG) Welding Process

Welding inspection is a critical process that can be severely time-consuming, resulting in productivity delays, especially when destructive or invasive processes are required. This paper defines the novel approach to investigate the physical correlation between common imperfections found in arc welding and the propensity to determine these through the identification of signatures using acoustic emission sensors. Through a set of experiments engineered to induce prominent imperfections (cracks and other anomalies) using a popular welding process and the use of AE technology (both airborne and contact), it provides confirmation that the verification of physical anomalies can indeed be identified through variations in obtained noise frequency signatures. This in situ information provides signals during and after solidification to inform operators of the deposit/HAZ integrity to support the advanced warning of unwanted anomalies and of whether the weld/fabrication process should be halted to undertake rework before completing the fabrication. Experimentation was carried out based on an acceptable set of parameters where extracted data from the sensors were recorded, analysed, and compared with the resultant microstructure. This may allow signal phenomena to be captured and catalogued for future use in referencing against known anomalies.

EVALUATION OF FILLET WELDS PROPERTIES PERFORMED BY COLD METAL TRANSFER ROBOTIC METAL ACTIVE GAS WELDING TECHNOLOGY

The article is the result of research evaluating the quality of fillet welds used in the production of rear seat backrests for passenger cars and manufactured robotically by Cold Metal Transfer (CMT) robotic Metal Active Gas (MAG) welding. When robotizing the process, parameters such as the speed of the process itself, accuracy and quality of the welded joints are important. Dual-phase ferritic-martensitic steel HCX 590X was used for the experiment and four weld nodes were evaluated. The quality of welded joints was evaluated by visual and capillary methods. Based on the metallographic analysis, the weld depth of the weld root was evaluated. The measured values were subsequently processed by statistical method ANalysis Of Variance (ANOVA). The research confirmed that the final quality of the welds depends on the depth of the weld root weld into the Base Material (BM). This parameter has the greatest effect on the welds made and results in the entire product being taken out of service.

Numerical and Physical Simulation of MAG Welding of Large S235JRC+N Steel Industrial Furnace Wall Panel

This paper presents the results of a study on the development of a Metal active gas (MAG) welding technology for an industrial furnace component made of steel S235JRC+N with respect to the minimizationof welding deformation. A numerical simulation of the welding process was performed in the first phase of the research. The numerical simulation was carried out with the SYSWELD software. For the numerical simulation of the welding process, the FEM method was used. In the simulation, four variants of restraint of the industrial furnace wall panel elements during the execution of the welding process were investigated. They differed in the number of restraints (model 1-4). It was found that the difference between the maximum mean strain in model 1 and the lowest mean strain in model 4 was only 11%. A physical simulation of the welding process was then performed with a restraint variant according to model 1. The displacement results obtained from the physical simulation of the welding process were compared with the displacement results from the numerical simulation. Discrepancies between numerical and physical simulation displacement values were found. The quality of selected welded joints was also evaluated. Visual testing (VT) and measurements of weld geometries were performed for this purpose. Metallographic tests and hardness measurements were performed to determine of influence of the welding process on the microstructure of the welded joint area, especially the heat affected zone (HAZ). The results obtained confirm the correctness of the assumptions made regarding the technology of manufacturing the furnace wall panels.

FTIR spectroscopy as a convenient tool for detection and identification of airborne Cr(VI) compounds arising from arc welding fumes

Given the significant presence of the carcinogenic Cr(VI) in arc welding fumes from stainless steels, it is also important, in addition to estimating the Cr(VI) levels, to identify Cr(VI) compounds, as it throws light on the mechanistic pathways towards fume formation. FTIR data is presented in this paper for arc welding fumes collected from Manual Metal Arc Welding (MMA), Flux Cored Arc Welding (FCAW) and Solid Wire Welding (Metal Inert/ Active Gas Welding [MIG/ MAG]). For MMA and FCAW samples, clear spectra corresponding to Na, K, dichromates was observed at wave number of around 725-740 cm-1 and at 890-900 cm-1. Chromate species were also observed at around 850-855 cm-1, as was evidence of CrO3 (chromium trioxide) too (950-970 cm-1). The identification of these compounds was done by carefully identifying the Cr-O-Cr anti-symmetric vibrations, the symmetric stretching of the CrO4 tetrahedra, and the stretching vibrations of the planar CrO3 structure for the chromium trioxide. All the above compounds were volatile, and present as nanoparticles in welding fumes, thereby potentially causing significant harm to the welders. Additionally, crystalline phases (Fe-Mn spinels) were also observed through powder XRD, and the data was compared with ion chromatography estimates for Cr(VI) and found to be consistent.

Investigation on the Microstructure and Mechanical Properties of ASTM A131 Steel Manufactured by Different Welding Methods

Abstract Welding is an indispensable manufacturing process in the shipbuilding industry. The fierce competition involved often necessitates a cost-effective and reliable welding method. In this study, the weldabilities, microstructures and some mechanical properties of ASTM A131 (Grade A) steel joints fabrication by submerged arc welding (SAW), metal active gas (MAG) welding and plasma arc welding (PAW) have been investigated. The microstructures of the welds were examined by optical microscopy. The mechanical properties of the joints were determined by microhardness measurements, tensile and impact tests. The results showed that tensile strength of the joints reached a tensile strength of up to 462 MPa. The locations of the fractures were always adjacent to the base metal. The Charpy impact energy of the weld metal reached a value of 72.5 J, which was 25 % higher than that of the base metal at 57.7 J. A relatively high hardness of 221 HV was obtained in the PAW method compared to 179 HV in the base metal.

Investigating The Effect of Nickel Buttering on Corrosion Resistance

Cladding is usually employed for improving corrosion and/or abrasion resistance of a component. Buttering layer between clad layer and structural steel is also sometimes provided to promote bonding between the cladding and the substrate. The buttering layer may also give desired corrosion resistance. Nickel is known to be a common austenite stabilizer, and it is often put inside cladding, coating, buttering, etc. to enhance hardness and corrosion protection of steel. In the current investigation, 316 austenitic stainless steel is deposited over nickel plated medium carbon steel substrate with the help of metal active gas welding. Nickel is accumulated on medium carbon steel by electroplating to act as a buttering layer. Welding current and torch travel speed, two important process parameters are varied with constant arc voltage to develop different values of heat input. Accelerated corrosion test in chloride atmosphere is done on ground and polished clad surface. Corrosion rate is observed to be decreased significantly for all the clad samples relative to the base material. However, no clear trend of corrosion rate against increment in heat input is found for reporting, but corrosion rate shows a typical pattern with the variation of heat input.

A Comparative Study of Mechanical and Microstructural Behavior for Metal Active Gas and Friction Stir Welded Micro-Alloyed Structural Steel

Manufacturing tiny components into gigantic structures seems unimaginable without welding connections, whether it is for materials, parts, structures, or equipment. In the recent competitive market scenario, manufacturing industries are desperately looking for a viable alternative to fusion-based conventional material joining technologies, to improve upon cost-effectiveness along with performance. The present investigation is to evaluate the performance of structural steel thick plate joints prepared by advanced solid-state friction stir welding (FSW) over conventional metal active gas welding (MAG). The FSW experiments were carried out with different tool designs and configurations. The outcomes were evaluated in terms of microstructural integrity and mechanical joint resistance. Impressive results were obtained with FSW joints, characterized by an almost defect-free microstructure with a leaner heat-affected zone and higher joint resistance as compared to conventional MAG-welded joints.

Welding Order and Welding Penetration Levels’ Impact on Product Life Cycle For GMAW

Gas metal arc welding is a high-speed, economical process that is also called as "metal inert gas welding" or "metal active gas welding" which are sub-types of gas metal arc welding. This method is used for production of different parts in many industries. In this paper, the focus will be on automotive applications of this process and the impact of the parameters of this production method on the durability performance of the axle component of a vehicle. Experiments have been conducted on the axles that have been produced in serial life production conditions and have been investigated under real life road load conditions to determine their performance levels. After theoretical calculations and physical tests, each measured improvement had been documented for every parameter of the welding process. All this data had been analyzed in detail and these parameters’ projected impacts on the axle life cycle had been evaluated with respect to the serial life usage condition expectations.

Evaluating Suitable Weld Condition to Obtain Enlarged Bead Width of 316 Stainless Steel Towards Weld Cladding

Usually bead-on-plate welding is performed to standardize process parameters before cladding. Selection of appropriate process parameters plays a vital role for achieving good weld bead geometry. In this experimental investigation, Metal Active Gas Welding is used with 316 austenitic stainless steel wire electrode. An experimental design for Response Surface Methodology named, Box-Behnken (Three Variable) design is adopted for determining the experimental runs. Heat input of 0.6kJ/mm and higher than this can be used to obtain desirable bead-on-plate welding that may also be recommended for weld cladding for this substrate-filler material combine.

Numerical investigation for dominant factors in slag transfer and deposition process during metal active gas welding using incompressible smoothed particle hydrodynamics method

Numerical simulation based on an incompressible smoothed particle hydrodynamics method was performed to clarify dominant factors of slag transfer and deposition processes in a metal active gas welding. The computational model considered the effects of a shielding gas flow on a slag floating on a weld pool surface. The computational result showed that the slags were generated on the weld pool surface near the centre of a heat source and were transferred to the edge of the pool. Those tendencies were similar to those observed in an experiment. The slags stayed at the trailing region of the pool and then deposited on a weld bead. These behaviours supported the validity of the present computational result. To identify the dominant factors of the slag behaviour on the weld pool, numerical experiments were conducted with individually acting forces due to the Marangoni effect, the shearing force, the Lorentz force, and the drag by the shielding gas flow. The computational results suggested that the shearing force and the drag due to the shielding gas were dominant near the centre of the heat source, and the slag was transferred from the vicinity of the heat source to the end of the weld pool. On the other hand, the force due to the Marangoni effect was dominant in the trailing region of the weld pool, and consequently, the slag was transferred from there to the front region in the welding direction.

Penetration and microstructure of steel joints by ultrasonic-assisted gas metal arc welding

This work investigates the application of ultrasonic vibration to steel joints formed by gas metal arc welding. Welding is done using a metal active gas welding source with welding current of 120–160 A, 0.8 mm diameter welding wire and 10 l min−1 CO2 flow. The distance from the torch to the ultrasonic horn is 120 mm. Ultrasonic vibration most affects the weld when ultrasonic vibration position is 120 mm from torch and increases the penetration when welding speed is 190 (275) mm/min for a 5 mm thick (10 mm thick) plate. Moreover, weld width increases when welding speed is 190 mm min−1 for 10 mm thick plate. Although ultrasonic vibration does not affect the hardness of welding zones, it modifies the microstructure of the diffusion and welding-pool zones.

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.