Submerged Arc Welding Process Research Articles

Thermodynamic Insights into the Influence of Welding Current on Oxygen Levels in the Submerged Arc Welding Process

Welding current is an essential parameter for submerged arc welding process. In submerged arc welding, the enormous heat generated by the current promotes the decomposition of the oxides in the flux, releasing oxygen and increasing the oxygen level in the metal, which further affects the microstructure and mechanical properties of the weld joint. Although previous studies have developed various models to evaluate oxygen content, the thermodynamic mechanism by which current influences oxygen levels in metal remains inadequately understood. This study integrates CALPHAD technology with welding thermodynamics to predict and simulate the impact of the welding current on oxygen content in metals. By combining experimental data with thermodynamic modeling, the research investigates how different current settings affect oxygen content in the metal across various welding zones, specifically when using CaO-Al2O3 fluxes with low and high basicity indices for the welding of typical carbon steel. This study selected two current values, 300 A and 600 A, for modeling analyses of the welding process, along with two typical fluxes with basicity indices of 1.6 and 0.4. The results indicate that the proposed method outperforms the BI model and can predict the metallurgical effects of current on oxygen content in the droplet and molten pool zones. The thermodynamic mechanisms that govern the metal oxygen level are also evaluated. These findings aim to enhance the understanding of the thermodynamic mechanism that governs oxygen behavior under different current conditions, thereby contributing to the optimization of submerged arc welding process.

Mechanical and metallurgical assessment of a submerged arc welded surfaced rail

The surfaces of rails are often damaged during constant loading, so it is essential to repair the damaged areas in a railroad network to get the best performance. However, the traditional methods of improving rails are expensive, time-consuming, and require excessive effort. Therefore, some creative ideas would be helpful in this process, one of which may be on-site overlay arc welding instead of exchanging the whole part of the rail. In this paper, the performance of such a method is assessed experimentally, and its results are interpreted.For the investigation, a worn part of the 136RE rail, used in the freight railway network in the U.S., was chosen. After milling and flattening the surface of the rail, a submerged arc welding process was applied to rebuild this rail by utilizing a 1/8-in Lincore 40-S depositing wire. This study used four destructive tests: 1) XRD residual stress measurement, 2) SEM/OM analysis, 3) hardness test, and 4) tensile test. The results showed that the required mechanical strength could be achieved. However, the repaired area seems more vulnerable to the forces encountered on a railroad network due to the more brittle structure due to high temperatures in this region. Considering this flaw is critical because forces are primarily dynamic in railway networks, especially in heavy rails, which are higher due to the extensive use of freight trains.

Maximizing welding efficiency: applying an improved whale optimization algorithm for parametric optimization of bead width in a submerged arc welding process

Maximizing welding efficiency: applying an improved whale optimization algorithm for parametric optimization of bead width in a submerged arc welding process

Influence of submerged arc welding process parameters and metallurgical behaviour in a thick carbon steel section for boiler application

AbstractThe aim of the research is to investigate the weldability of thick sections of carbon steel using submerged arc welding with varying process parameters. The experimental design for joining thick carbon steel involves manipulating input weld process parameters such as current (A), voltage (V), weld speed (mm/h), and weld electrode diameter (mm). The quality of the weld material is assessed based on transformations in microstructure, weld hardness measured by Brinell hardness number, and tensile strength (MPa). It is crucial to note that the grain structure and metallurgical behavior of other hard materials may differ significantly. The presence of carbon in the ferrite phase has led to the formation of bainite, martensite, and composites of martensite and austenite within the weld zone, as confirmed by high‐resolution microscopy. The weldment‘s hardness has increased from 242.5 HV 30 in the base metal to 316.4 HV 30 in the weldment due to metallurgical alterations in the microstructure. Weld energy input emerges as the primary factor influencing weld quality. With increasing weld current and voltage, there is a corresponding increase in the joined metal, resulting in improved characteristics in the weld structure, particularly at maximal energy input and welding speed. In the context of boiler applications, understanding the weldability of thick carbon steel sections is paramount for ensuring structural integrity and longevity under high‐temperature and high‐pressure conditions. The optimized welding parameters identified in this study can contribute to enhancing the reliability and performance of boilers, thereby promoting safety and efficiency in industrial settings.

Timed Thermodynamic Process Model Applied to Submerged Arc Welding Modified by Aluminium-Assisted Metal Powder Alloying

An EERZ (effective equilibrium reaction zone) model was applied to the modified SAW (submerged arc welding) process to simulate the SAW process metallurgy in the gas-slag-metal reaction system. The SAW process was modified by adding Al as a de-oxidizer with alloying metal powders of Cr, Cu, and Ti. The static gas-slag-metal equilibrium model can accurately calculate the weld metal oxygen content (ppm O) for conventional SAW but not for the modified SAW process. The static equilibrium model overpredicts the reaction of Al. EERZ model runs were made for 2000–2500°C because this is the reported temperature range in the SAW arc cavity. The weld metal composition was adequately calculated, especially the weld metal ppm O, at the following effective equilibrium temperatures: 2400°C for Al-Cr additions, 2200°C for Al-Cr-Cu additions, and 2000°C for Al-Cr-Cu-Ti additions. Model results show that Ti metal powder can serve a de-oxidizer role in the presence of Al, resulting in Ti loss to the slag. Ti is also lost to the gas phase as TiF3(g) and TiF2(g) compared to little loss of Cr to the gas phase as Cr(g) and CrO to the slag phase.

Determining process parameters for optimum weld quality in submerged arc welding process of mild steel using a hybrid Fuzzy-MABAC approach

Determining process parameters for optimum weld quality in submerged arc welding process of mild steel using a hybrid Fuzzy-MABAC approach

Submerged arc welding process: enhancement of production performance based on metallurgical observations

Welding processes are widely used technologies in the industrial context for creating permanent connections between mechanical components. This popularity is due to their versatility, which arises from the numerous available process variants and the multiple advantages they offer compared to other joining techniques. In the manufacturing context, where devices often operate in extreme conditions, the quality of welds becomes a critical factor in ensuring the safety and reliability of the manufactured products. Furthermore, a sound joint requires careful compliance with the increasingly stringent design specifications demanded by customers who require industry-standard conformity in order to achieve defect-free, robust, and durable welds. To address these needs and to define the optimal roadmap for the investigated process condition, an experimental investigation was conducted on the submerged arc welding process. The experimental trials involved butt joints of ASTM A516 Gr.70 carbon steel plates with different thicknesses in a flat position, utilizing a U-shaped chamfer and a multi-pass welding technique. For each weldment, the effects of the main process parameters on the qualitative characteristics of the manufactured products were evaluated from a metallurgical perspective. This evaluation included an in-depth metallographic analysis of the heat-affected zone of the carbon steel joint and involved both the measurement of the dimensions of these areas as well as the amount of ferrite and pearlite that resulted as the phases observed in the final microstructure of the steel joint following its solidification. Furthermore, the joint quality was assessed with regard to mechanical strength through hardness measurements. By analysing the experimental data, the paper provides a valuable contribution for increasing the productivity of the investigated welding process, while simultaneously meeting the specified industrial quality requirements for the products made of medium-thickness carbon steels.

Optimizing Elemental Transfer Predictions in Submerged Arc Welding via CALPHAD Technology under Varying Heat Inputs: A Case Study into SiO2-Bearing Flux

With the advancement of the manufacturing industry, performing submerged arc welding subject to varying welding heat inputs has become essential. However, traditional thermodynamic models are insufficient for predicting the effect of welding heat input on elemental transfer behavior. This study aims to develop a model via CALPHAD technology to predict the influence of heat input on essential elements such as O, Si, and Mn when typical SiO2-bearing fluxes are employed. The predicted data demonstrate that the proposed model effectively forecasts changes in elemental transfer behavior induced by varying welding heat inputs. Furthermore, the study discusses the thermodynamic factors affecting elemental transfer behavior under different heat inputs, supported by both measured compositions and thermodynamic data. These insights may provide theoretical and technical support for flux design, welding material matching, and composition prediction under various heat input conditions subject to submerged arc welding processes when SiO2-bearing fluxes are employed.

Nano-Strand Formation via Gas Phase Reactions from Al-Co-Fe Reacted with CaF2-SiO2-Al2O3-MgO Flux at 1350 °C: SEM Study and Thermochemistry Calculations

The submerged arc welding (SAW) process is operated at high temperatures, up to 2500 °C, in the arc cavity formed by molten oxy-fluoride flux (slag). These high arc cavity temperatures and the complex interaction of gas–slag–metal reactions in a small space below the arc render the study of specific chemical interactions difficult. The importance of gas phase reactions in the arc cavity of the SAW process is well established. A low-temperature (1350 °C) experimental method was applied to simulate and study the vaporisation and re-condensation behaviour of the gas species emanating from oxy-fluoride flux. Energy dispersive X-ray spectroscopy (EDX) analyses and reaction thermochemistry calculations were combined to explain the role of Al as a de-oxidiser element in gas phase chemistry and, consequently, in nano-strand formation reactions. EDX element maps showed that the nano-strands contain elemental Ti only, and the nano-strand end-caps contain Co-Mn-Fe fluoride. This indicates a sequence of condensation reactions, as Ti in the gas phase is re-condensed first to form the nano-strands and the end-caps formed from subsequent re-condensation of Co-Mn-Fe fluorides. The nano-strand diameters are approximately 120 nm to 360 nm. The end-cap diameter typically matches the nano-strand diameter. Thermochemical calculations in terms of simple reactions confirm the likely formation of the nanofeatures from the gas phase species due to the Al displacement of metals from their metal fluoride gas species according to the reaction: yAl + xMFy ↔ xM + yAlFx. The gas–slag–metal equilibrium model shows that TiO2 in the flux is transformed into TiF3 gas. Formation of Ti nano-strands is possible via displacement of Ti from TiF3 by Al to form Al-fluoride gas.

Waste to wealth: development of cladding flux from steel slag for submerged arc welding

A novel methodology has been developed which permits to transform waste slag into welding flux meant for stainless steel cladding. The developed flux has been applied for stainless steel cladding using submerged arc welding process. The claddings prepared using developed flux has been evaluated in terms of bead geometry, mechanical properties and chemical composition. The depth of penetration, weld bead width and height of reinforcement achieved with developed flux are 7.64 mm, 14.01 mm, and 4.07 mm, respectively, which are superior than obtained with fresh flux (8.05 mm, 12.85 mm, and 3.44 mm), as far as cladding is concerned. It observed that the developed flux is capable to produce chemical composition of claddings as per ASME SFA 5.4 standard. The percentage of chromium, nickel and manganese in claddings is 18.1%, 8.56% and 1.04% respectively which satisfy the ASME requirements. The side bend test proves a good bonding strength between substrate and claddings. The hardness of claddings produced with developed flux is also comparable with that of fresh flux. The average hardness of cladding produced with developed flux is 459 Hv, compared with that of fresh flux (435 Hv). The cost of developed flux is 54.86% economical than that of fresh flux. This research advocates that steel slag could be utilized as a raw material for manufacturing welding flux for stainless steel cladding.

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.