Submerged Arc Welding Process Research Articles

Experiment and FEA simulation for predicting maximum distortion in the submerged arc welding process

Experiment and FEA simulation for predicting maximum distortion in the submerged arc welding process

Modeling the weld bead penetration in the presence of Cr2O3 nanoparticles in the submerged arc welding process using a modified neuro-fuzzy system

Modeling the weld bead penetration in the presence of Cr2O3 nanoparticles in the submerged arc welding process using a modified neuro-fuzzy system

Low temperature vaporisation of Cr from fluoride flux reacted at 1350 °C with Al–Cr–Fe powder: Thermochemical analysis of gas phase reactions and nano-strand formation

The submerged arc welding (SAW) process is complex because multi-phase reactions occur simultaneously across a large temperature interval from 2500 °C in the arc cavity, down to the weld pool liquidus temperare at the slag-weld pool interface. This complexity hinders research on specific process metallurgy aspects, such as gas formation from the oxy-fluoride slag. The main objective of this work is to illustrate a low temperature experimental technique as an accurate reaction simulation experiment of SAW flux oxy-fluoride slag behaviour in terms of gas formation and metal powder assimilation reaction mechanisms as observed in the SAW process. The oxy-fluoride slag behaviour was confirmed by identification and analyses of nano-strand formation in the reacted slag formed from the reaction of welding flux with Al-Fe-Cr metal powders at 1350 °C. The observed nano-strand formation agrees with similar observations in SAW post-weld slags used to confirm of oxy-fluoride vaporisation and re-condensation. Element distribution from energy dispersive X-ray spectroscopy (EDS) maps and thermochemical calculations were used to gain insights into the reactions in nano-strand formation. The nano-strands contained chromium patches and spots of less than 1 μm in scale, confirming that added Cr metal powder assimilated via the gas phase. Cr-fluoride formed part of the oxy-fluoride slag and likely formed Cr-fluoride gas. Cr was recovered via re-condensation of Cr vapour formed from the reaction of Cr-fluoride with Al gas. This work presents an accurate low temperature simulation method of gas formation and metal powder assimilation reactions in oxy-fluoride slags as in the SAW process.

Advancing Methodologies for Elemental Transfer Quantification in The Submerged Arc Welding Process: A Case Study of CaO-SiO2-MnO Flux

In submerged arc welding, evaluating elemental transfer behaviors is critical for selecting and designing welding materials. Accurate assessment of O, Si, and Mn transfer behavior is essential for ensuring process quality, particularly when silicon-manganese fluxes are applied. Traditional quantification methods, however, focus only on chemical reactions in the weld pool zone, potentially overlooking the cross-zone elemental transfer behavior and leading to significant predictive inaccuracies. This study investigates the CaO-SiO2-MnO flux, a prevalent silicon-manganese flux, focusing on O, Si, and Mn, which exhibit notable transfer behaviors of O, Si, and Mn. By employing a multi-zone approach and integrating various scientific principles, the research aims to improve the accuracy of predicting elemental transfer behaviors and deepen the understanding of the metallurgical processes in submerged arc welding when silicon-manganese fluxes are employed. The study proposes strategic enhancements to traditional quantification methods, which may offer valuable insights for the improvement of industry standards. This study demonstrates that considering only the local thermodynamic equilibrium of the weld pool zone when quantifying the transfer behavior of elements may lead to predictive errors, especially for easily evaporating metallic elements. By incorporating a cross-zone assessment for submerged arc welding process, i.e., introducing new quantifying parameters (Δd and Δw), the predictive accuracy of the transfer behavior of elements and their cross-zone actions can be enhanced.

Nano-strand formation in CaF2-SiO2-Al2O3-MgO flux reacted at 1350 °C with Al-Ti-Fe powder: SEM analyses and gas reaction thermochemistry

Nano-strands form in fluoride-based slag during submerged arc welding (SAW) due to the re-condensation of gas species formed at high temperatures in the arc cavity. The SAW process is complex due to gas-slag-metal reactions occurring across several reaction zones and over a wide temperature range. This complicates research on specific process aspects, such as gas formation from the oxy-fluoride slag. The objective of this work is to demonstrate that oxy-fluoride nano-strands form in molten flux reacted with Al-Ti-Fe metal powder, even at the low temperature of 1350 °C, which is much lower than SAW process temperatures of 2000 °C–2500 °C. Energy dispersive X-ray spectroscopy (EDS) analyses and thermochemical calculations provide insights into formation reactions in nano-strand formation. Thermochemical analysis clarifies the role of Al in shifting the gas phase composition to limit Ti-fluoride loss to the gas phase. These results motivate the study of gas phase reactions at relatively lower reaction temperatures to gain insights into SAW flux behaviour.

Multi-Objective Optimization of Welding Processes Using Modified Rao Algorithms

The welding community faces a challenging problem in choosing the best welding methods since they are multi-input processes. Modern manufacturing industries have requirements to get fast and optimum process parameters to utilize complete resources in an optimum way. This work attempts to improve the performance of submerged arc welding (SAW), friction welding (FW), and gas tungsten arc welding (GTAW) processes by optimizing their parameters. The newly developed Rao algorithms and their modified versions known as quasi-oppositional Rao (QO Rao), self-adaptive multi-population elite Rao (SAMPE Rao), and improved Rao (I-Rao) are used. This paper contains four multi-objective optimization case studies of SAW, FW, and GTAW processes. A weighted approach is employed to tackle the multi-objective optimization problems effectively. The outcomes achieved using the Rao, QO Rao, SAMPE Rao, and I-Rao algorithms are compared with those obtained by the established optimization algorithms such as accelerated cuckoo optimization algorithm (ACCOA), cuckoo optimization algorithm (COA), plant propagation algorithm (PPA), teaching–learning-based optimization (TLBO) algorithm, Jaya algorithm, quasi-oppositional Jaya (QO Jaya) algorithm, genetic algorithm (GA), particle swarm optimization (PSO) algorithm, and heat transfer search (HTS) algorithm. The effectiveness of the Rao algorithms and their modified versions has been clearly demonstrated as these algorithms have provided superior solutions while requiring fewer generations to achieve them.

Submerged Arc Welding of SA 516 Gr70 Material: Parametric Optimization of Mechanical Properties UT-Strength and Hardness

In this study, the Taguchi technique was employed to optimize the process parameters of submerged arc welding (SAW) in terms of mechanical properties such as Ultimate Tensile Strength (UTS) and hardness. The study considered a variety of weld quality factors and provided a detailed explanation of the procedure and results using the Taguchi method, which is a statistical analysis approach that requires fewer trials. The experiment was conducted on SA 516 GR70 material using a L9 orthogonal array and a range of current, voltage, and speed settings. The comparison of anticipated and experimental values with the mathematical model of regression analysis-ANOVA with and without interaction helped in achieving the desired results. Lastly, a verification experiment confirmed that the Taguchi technique is reliable in predicting UTS and hardness performance. Overall, this research provides valuable insights into optimizing the SAW process parameters for mechanical properties and demonstrates the effectiveness of the Taguchi technique in predicting and achieving optimal welding performance.

Investigation on the Metal Transfer and Cavity Evolution during Submerged Arc Welding with X-ray Imaging Technology

The physical phenomena of submerged arc welding (SAW) conducted with a 1.6 mm flux-cored wire were investigated using X-ray imaging technique. Three kinds of metal transfer modes were confirmed in this paper, namely the front flux wall-guided droplet transfer, back flux wall-guided droplet transfer, and repelled droplet transfer, of which the corresponding percentages were 47.65%, 45.29%, and 7.06%, respectively. Although the average sizes of the droplets for SAW and FCAW (flux-cored wire welding) were 2.0 mm and 1.9 mm with an average droplet transfer time of 90.3 ms, it required 36.4% more time for the droplet of SAW to finish one metal transfer than it did in FCAW. In addition, the volume of the cavity was not constant but repeated a cycle mode of “expansion and contraction” during the whole process. Thus, the dynamics of the cavity and viscous resistance caused by the flux collectively slowed down the velocity of the droplets from the wire to the weld pool in SAW. Compared with FCAW, a smoother weld without pits and pores was manufactured during the SAW process. Due to the compression effect of the flux, the 14.5 mm average weld width of SAW was 2.9 mm shorter than that of the FCAW. Furthermore, the thickness of slag with a porous structure in SAW was 2.7 times of that in FCAW, indicating that it could provide better protection to the weld of SAW.

Influence of welding conditions and flux composition on chemistry of welds using recycled steel slag in submerged arc welding

The slag generated by steel-making plant has been employed to manufacture flux essential for submerged arc welding process. The developed flux has been used for depositing beads on plates, and the weld metal chemistry has been evaluated. The effect of welding conditions and flux composition on element transfer behavior has been investigated. The experiments were carried out as dictated by the design matrix generated using CCRD in response surface methodology. The data generated during experimentation was used to develop mathematical models. The developed models were tested for their adequacy through the ANOVA technique in design expert software. It is interesting to note that the recycled slag provided the chemistry of weld metal which is accepted as per ASME specifications. The rise in welding current increases the amount of carbon in weld metal from 0.11 to 0.14 wt.%, whereas it decreases with increasing travel speed. Manganese content decreases (1.28 wt.% to 0.795 wt.%) with increasing welding current (250 A to 650 A). The increase in welding speed from 4.44 mm/s to 8.88 mm/s results in an increment in manganese content from 0.87 wt.% to 1.21 wt.%. Since increasing travel speed decreases heat input per unit length of the weld, evaporation of manganese is suppressed. Therefore, the highest manganese content was achieved at a lower current (250 A) and higher speed (8.88 mm/s). Smooth beads with evenly distributed ripples free from surface defects like undercuts, porosity, pockmarks, etc., were achieved.

Microstructural analysis of martensitic hard surfacing on low chromium alloy steel

AbstractThis study focuses on the metallurgical characterization of single and multi‐layer martensitic hard surfacing onto non‐standardized low‐chromium alloy steel with a single buttering layer using an automatic submerged arc welding process as a standard reference. The metallurgical properties of hard surfaced samples are examined using an optical microscope, energy dispersive x‐ray spectroscopy, and x‐ray diffractometer. Micro‐Vickers hardness testing is also conducted to analyze and confirm the metallographic results of hard surfacing. The current study finds that the microstructure of each region is influenced by three key factors: chemical composition, heat input, and dilution. The structural type is determined by the chemical composition of materials, heat input influences the structural characteristics in the heat‐affected zone (needle‐shape martensite and tempered martensite), and dilution affects the structural characteristics of the hard surfacing layers (martensite with retained austenite). Comparing multi‐layer hard surfacing to single‐hard surfacing, the hardness values of the heat‐affected zone of the multi‐layer hard surfacing are greatly reduced, while the hardness values of the hard surfacing layers are raised.

Evaluation of crane wheels restored by hardfacing two distinct 13Cr-4Ni martensitic stainless steels

Depositing two martensitic stainless steel filler metals with chemically different composition, crane wheels were restored to study the development of mechanical properties and wear resistance. For this purpose, a two-layer clad was deposited using each filler metal through submerged arc welding process. Microstructural evolution shows that solidification modes are different in the hardfaced clads due to the discrepancy in the ratio of chromium equivalent to nickel equivalent (Creq/Nieq). A reduction in Creq/Nieq leads to the enrichment of liquid metal in austenite-promoter elements, resulting in the presence of austenite phase in the matrix, as identified by XRD pattern. Following a post-weld heat treatment in the constant temperature of 500 °C for an hour, apart from the tempered martensite, fresh martensite as a consequence of transforming austenite phase is formed in the matrix. This transformation significantly increases the mean value of microhardness from 360 to 462 HV0.3. Also, uniaxial tensile test shows that the formation of fresh martensite approximately limits the elongation of the clad. The fractography studies show that the fracture mode in both clad is the same and ductile, with embedded carbides in dimples. Tribological behavior of the clads shows that the formation of fresh martensite in the clad results in higher wear resistance, with specific wear rate of 1.8 × 10−5 mm3/Nm at the maximum load. In addition, oxidative wear mechanism is dominant at lower load of 10 N, while the wear mechanism changes at higher load of 60 N to severe plastic deformation.

Improving the Accuracy of Silicon Transfer Prediction in Submerged Arc Welding: A Multi-Reaction-Zone Analysis

This study aims to predict and evaluate the transfer behavior of silicon employing SiO2-bearing fluxes during submerged arc welding. Unlike previous studies that only focused on chemical reactions in the weld pool zone, this research investigates the elemental behavior of silicon subjected to essential reaction zones in a submerged arc welding process. The proposed method is compared with the traditional thermodynamic equilibrium models, enhancing the understanding of silicon transfer behavior in the submerged arc welding process. It is demonstrated that relying solely on thermodynamics within the weld pool zone is inadequate for accurately predicting the extent of silicon transfer level since the loss of silicon during the droplet zone and the improvement in oxygen content in the molten droplet are not considered, resulting in an overestimation of the ΔSi level. Finally, the limitations of the traditional elemental transfer quantification method and corresponding corrective suggestions are proposed.

Submerged arc welding process: a numerical investigation of temperatures, displacements, and residual stresses in ASTM A516-Gr70 corner joined samples

Arc welding processes represent an important category of fusion welding techniques. They are characterised by the use of an electric arc to create heat to melt and join metals. Submerged arc welding belongs to this process category. Its peculiarities are mainly related to the employment of a continuously fed electrode and of a powdered flux to cover the arc providing electrical conduction between electrode and metals to be connected and, at the same time, generating protective gas and slag shields. Current (I), voltage (V), and welding speed (v) are the main process variables, properly set, to guarantee the specific heat (SH) required to achieve sound weld beads. In this research, finite element models were built looking at the macrographs extracted by experimental tests performed in two steps in order to obtain the real area of each pass and setting different welding conditions. Different combinations of I, V, and v were proposed providing, however, a fixed SH to the welding zone according to the required industrial standards. Specifically, tests were executed increasing the ratio V to v (for a constant I) and the ratio I to v (for a constant V) and with a different combination of V and I maintaining constant their product (for a constant v). The influence of the investigated variables’ combination on the weld pool in terms of depth and width was discussed. Finally, the validated numerical models were employed to highlight precisely residual stresses and displacements trend on cross-sectioned weld beads connecting the shown tendencies to the investigated process conditions.

Effect of Heat Treatment on Microstructure, Mechanical Properties, and Corrosion Performance of 410NiMo Super Martensitic Stainless Steel Cladded on 21CrMoV5-11 by Submerged Arc Welding Process

Effect of Heat Treatment on Microstructure, Mechanical Properties, and Corrosion Performance of 410NiMo Super Martensitic Stainless Steel Cladded on 21CrMoV5-11 by Submerged Arc Welding Process

Analysis of the process of qualifying the welding technology of S355JR structural steel using the submerged arc welding method

This paper presents the issue of welding technology qualification using the example of structural steel S355JR with a plate thickness of 25 mm and 100 mm, bevelling V. The main objective of this work was to attempt to perform a full qualification of the submerged arc welding process in accordance with the requirements of PN EN ISO 15614. Particular attention was paid to the issue of the qualification of welding technology. The samples were subjected to non-destructive testing, i.e. visual and penetrant testing, as well as ultrasonic testing and heat treatment. This was followed by destructive testing, including macroscopic testing and hardness testing. According to the proposed procedure for the recognition of submerged arc welding technology, once the necessary tests had been carried out and the protocols with positive results had been obtained. The documentation had been completed, the analysis needed to obtain certificates of conformity for factory production control and welding quality was carried out.Submerged arc welding is often used for highly responsible butt joints, particularly when joining thick components. This has been achieved through the proper design of the preparation of the parts to be welded and the development of a welding technology that practically eliminates the pre-phase that occurs in traditional technology, thereby eliminating the risk of it affecting the quality of the welded joint.During the implementation of submerged arc welding, a number of technological problems were encountered. The first test joints contained many defects, i.e. sticking and slag inclusions inside the welds. In addition, obtaining welds with the correct profile and removing the slag from the weld groove was difficult. These obstacles were eliminated experimentally by carrying out successive tests using different parameters and welding groove geometries.The correct implementation of any welding process depends on its input parameters. These parameters include welding current, welding speed, welding current, wire diameter, welding voltage and many others. Submerged arc welding (SAW) is widely used in the industry for manufacturing as it is more reliable, provides deep penetration in the work, ensures a smooth finish on objects, and results in high productivity.The technology was developed for a company that manufactures control discs for steam turbines.

Advancing Manganese Content Prediction in Submerged Arc Welded Metal: Development of a Multi-Zone Model via the Calphad Technique

Manganese is a vital element in determining the mechanical properties of submerged arc welded metal. To ensure a reliable weld, the equilibrium model has been used for decades to predict and control the manganese content, particularly when MnO-bearing fluxes are applied. However, the equilibrium model only considers chemical interactions within the weld pool zone, leading to significant inaccuracies. To address this limitation, we propose a multi-zone model that accounts for all of the essential reaction zones in the submerged arc process via the Calphad technique. The model’s accuracy is verified by predicting the manganese content, the flux oxygen potential, and the neutral point location for the typical MnO-bearing fluxes covering acidic, neutral, and basic fluxes. The results indicate that the multi-zone model offers superior accuracy compared to the equilibrium model, which neglects significant oxygen improvement and alloy evaporation in the droplet zone. Further analysis of thermodynamic data reveals that the multi-zone model provides a more representative depiction of the variation trends in oxygen and manganese contents during the submerged arc welding process compared to the equilibrium model. Furthermore, this model can be utilized in the optimization of the submerged arc welding process, leading to improved quality and efficiency in heavy engineering industries. This study may provide an improved method for predicting the manganese content in welded C-Mn steel and deepen the understanding of manganese transfer mechanisms during the submerged arc welding process.

Investigation of welding of dissimilar high thickness SA106 Gr.C carbon steel and SA335P12 alloy steel to eradicate the failure in boiler components fabricated through SAW and SMAW processes

This study reports the effect of Shielded metal arc welding (SMAW) and Submerged arc welding (SAW) processes used to fabricate high-thickness end cover plates by welding of dissimilar materials SA 335 P12 steel pipes and ASTM A 106 grade C carbon steel. The study emphasizes the structure-property relation of the welded joints made by two different techniques using macrostructure and microstructural examination with optical and electron microscopy and hardness evaluation. The joints were subjected to magnetic particle non-destructive testing and the SAW joint was found to be defect-free. Microstructural examination revealed acicular ferrite microstructure on the SAW joint but bainite and martensite microstructure on the SMAW joint. After heat treatment hardness values disclosed the dissolution of the hard phases. The joints fabricated with SAW demonstrated high ductility with an increase in elongation of 23% and 37.5%, during the bend test and the tensile test respectively. Higher thickness welding of dissimilar joints by SAW is prefereed over SMAW joints, as it requires fewer weld passes and produce superior weld quality without any defects.

Gas Formation of Cobalt and Copper in the Application of Unconstrained Co-Cr-Al-Cu Metal Powders in Submerged Arc Welding: Gas Phase Thermodynamics and 3D Slag SEM Evidence

Aluminium metal is not typically added to the submerged arc welding (SAW) process because it is easily oxidised to form unwanted slag in the weld pool. The successful application of aluminium as a de-oxidiser is illustrated in this study by preventing oxidation of Cr and Co to their oxides, thereby preventing element loss to the slag. Unconstrained pure metals of Al, Cr, Co and Cu were applied to investigate the gas formation behaviour of these elements in the SAW arc cavity. Of interest is the effect of copper in the arc cavity in terms of its possible substitution for aluminium. The results confirmed that the Al-Cr-Co-Cu alloyed weld metal total oxygen content was lowered to 176 ppm O, in comparison to 499 ppm O in the weld metal formed from welding with the original flux, which excluded metal powder additions. This lower ppm O value of 176 ppm O confirms that the added aluminium powder effectively lowered the original flux-induced partial oxygen pressure in the arc cavity, and at the molten flux–weld pool interface. Carbon steel was alloyed to 5.3% Co, 5.5% Cr, 5.3% Cu and 4.5% Al at 78% Co yield, 82% Cr yield, 78% Cu yield and 66% Al yield. Thermochemical equilibrium calculations confirm the partial oxygen pressure-lowering effect of aluminium when considering the gas–slag–alloy equilibrium. BSE (backscattered electron) images of the three-dimensional (3D) post-weld slag sample show dome structures which contain features of vapour formation and re-condensation. SEM-EDX (scanning electron microscope-energy dispersive X-ray) maps show that the dome surface matrix phase consists of Al-Mg-Ca-Si-Na-K-Ti-Fe-Mn oxy-fluoride. The spherical 3D structures of 10–40 µm in diameter consist of Fe-Mn-Si fluorides with some Cr, Cu and Co contained in some of the spheres. Cr and Co were observed in distinctive porous structures of approximately 10 µm in size, consisting partly of Cr oxy-fluoride and partly of Co oxy-fluoride. Nano-sized oxy-fluoride strands and spheres in the dome structures confirm vaporisation and re-condensation of oxy-fluorides. Cu and Na formed a distinct condensation pattern on the surface of the Si-Cu-Na-Mn-Fe-Co oxy-fluoride sphere. The results confirm the importance of including gas phase reactions in the interpretation of SAW process metallurgy.

Thermodynamic Simulation of O Content Variation Roadmap in Submerged Arc Welding Process: From Droplet to Weld Metal

Submerged arc welding is a complex metallurgical system involving various phases with a temperature higher than 2000 °C. Since the hot weld pool is shielded beneath the flux, thermodynamic investigation on the O content variation during the welding process remains nebulous. Within this framework, a thermodynamic approach has been proposed to estimate the variation tendency of O content in metal during the overall submerged arc welding process. The modeling is based on the assumptions of Oxygen Layer Theory, Local Attained Equilibrium, and Scheil Solidification. The simulated and measured data show that this approach is capable of predicting the variation of the O content roadmap when typical CaO–Al2O3 based fluxes are employed. Then, factors pertinent to the level of O content are evaluated from thermodynamic perspectives. Additionally, it is revealed that the decomposition mechanisms of the oxides in welding can be constrained via the incumbent approach.

A Review of the Thermochemical Behaviour of Fluxes in Submerged Arc Welding: Modelling of Gas Phase Reactions

This review is focused on the thermochemical behaviour of fluxes in submerged arc welding (SAW). The English-language literature from the 1970s onwards is reviewed. It was recognised early on that the thermochemical behaviour of fluxes sets the weld metal total ppm O and the element transfer extent from the molten flux (slag) to the weld pool. Despite the establishment of this link between the flux-induced oxygen potential and element transfer, it is also well accepted that the slag–metal equilibrium does not control SAW process metallurgy. Instead, the gas phase must be taken into account to better describe SAW process metallurgy equilibrium calculations. This is illustrated in the gas–slag–metal equilibrium simulation model developed by Coetsee. This model provides improved accuracy in predicting the weld metal total ppm O values as compared to the empirical trend of Tuliani et al. Recent works on the application of Al metal powder with alloying metal powders provide new insights into the likely gas phase reactions in the SAW process and the modification of the flux oxygen behaviour via Al additions. Aluminium may lower the partial oxygen pressure in the arc cavity, and aluminium also lowers the partial oxygen pressure at the weld pool–slag interface. The weld metal total ppm O is lowered with the addition of aluminium in SAW, but not to the same extent as would be expected from steelmaking ladle metallurgy de-oxidation practice when using Al as de-oxidiser. This difference indicates that slag–metal equilibrium is not maintained in the SAW process.