Welding Flux Research Articles

Structure and properties of the welded joint during arc welding of low-carbon steel under a layer of flux obtained from metallurgical slag of electric steelmaking

The results of the study of the influence of the thermophysical properties of the welding flux obtained by processing man-made waste of electric steelmaking (metallurgical slag) on the structure and properties of welded butt joints of thin-sheet low-carbon steel, with automatic arc welding on ceramic linings, are presented. Welding modes have been established using the developed flux, contributing to the achievement of seam sizes according to GOST8713–79, C4 joints, compliance with the mechanical properties of joints close to the base metal and ensuring a minimum level of welding deformations and stresses.

Elucidating Electrical Conductive Mechanisms for CaF2–SiO2–Al2O3–MgO Welding Fluxes in Liquid and Crystalline States

Elucidating Electrical Conductive Mechanisms for CaF2–SiO2–Al2O3–MgO Welding Fluxes in Liquid and Crystalline States

SiO2-bearing Fluxes Induced Evolution of γ Columnar Grain Size

Understanding the controlling mechanisms of γ columnar grain size in the weld metal of low-carbon, low-alloy steel is critical for optimizing resultant microstructures and the weld metal’s ensuing properties. Here, we investigate the role of welding flux composition upon the γ columnar grain size by submerged arc welding of EH36 shipbuilding steel with designed CaF2-SiO2 fluxes. We found that the addition of SiO2 from 5 to 40 mass-% increases average columnar grain size by a factor of nearly 2.5, which results from the change of the weld pool solidification mode from peritectic to primary δ solidification. Such a change is directly related to element transfer behaviors between the flux and the weld metal. Furthermore, we offer compelling evidence that alterations in γ columnar grain size are not primarily governed by significantly populated inclusions and/or weld metal macro-morphological changes. Our findings may largely serve as a viable strategy toward designing welding consumables to match base metals to ensure the soundness of the weldment.

Melting Behavior of a CaO–SiO2–Al2O3 Flux with Varying MnO Concentration for Use in Fusion Welding of Low‐Carbon Steel

CaF2 has been a very common constituent in the fluxes used for welding of low‐carbon steel plates, owing to its strong ability to lower the liquidus temperature as well as viscosity of the molten flux. But the adverse impact of fluoride evaporation from molten slag on the health of operating personnel and the environment has prompted a worldwide effort to replace CaF2 with more benign constituents. Three compositions with varying MnO concentration in the CaO–MnO–SiO2–Al2O3 system, identified in the current work, have shown promise in terms of ability to control oxygen transfer and modify inclusion generation in the molten metal during the welding of low carbon low alloy steels. However, the melting behavior of a flux needs to be established before recommending its use for welding. Three compositions, with varying MnO concentration, are chosen in the current work. Aided by experimental measurements using high‐temperature microscopy, DTA and simulations using the commercially available thermodynamic package FactSage (version 8.3), this work aims to understand the melting characteristics of the developed fluxes. These characteristics seem to be comparable with a commercial CaF2‐containing welding flux, used as a reference for comparison. In addition, simulations using FactSage suggest that transfer of dissolved O, Si and Mn to the weld metal, while using these fluxes, would be benefitial to performance of the welded joint.

Investigation of the alloying elements effect in the flux-cored wire and submerged arc welding flux combination

Investigation of the alloying elements effect in the flux-cored wire and submerged arc welding flux combination

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.

INVESTIGATION OF THE NA+, K+ || VO3–, SO42– TERNARY RECIPROCAL SYSTEM AND MEASUREMENT OF THE NONVARIANT COMPOSITIONS MELTING ENTHALPY

Functional compositions based on multicomponent systems of oxygen-containing salts of s1-elements are widely used in various fields of industry, science and technology: electrometallurgy of light, refractory and heavy metals, as well as metallothermy, pyrometallurgy, promising fluxes for welding and soldering metals, chemical power sources. In the work the triangulation of the Na+, K+ || VO3–, SO42– ternary reciprocal system of sulfates and metavanadates of sodium and potassium on simplices was carried out. The phase states of the Na+, K+ || VO3–, SO42– ternary reciprocal system was investigated by differential thermal analysis (DTA). T–x diagram of the stable secant K2SO4–NaVO3 was constructed, which is the diagonal of the system composition square and which has a eutectic with a melting point of the quasi-double eutectic of 575 °C and a specific melting enthalpy value of 206 kJ/kg. In the NaVO3–Na2SO4–K2SO stable triangle, a minimum of solid solutions with a temperature of 559 °C and an enthalpy of 190 kJ/kg was determined. In the NaVO3–KVO3–K2SO4 stable triangle, the three-component eutectic with a minimum melting point in the system of 474 °C has a minimum specific melting enthalpy of 183 kJ/kg. Compositions of the triple peritectic Р 482 °С and the three-component minimum of solid solutions M 559 °С were determined. The maximum crystallization fields of the system composition square correspond to potassium sulfate and continuous solid solutions of sodium and potassium sulfates. Low-melting mixtures of quasi-double eutectic, ternary eutectic, and ternary minimum can be used as molten electrolytes for medium-temperature chemical current sources and as heat storage materials. For citation: Istomova M.A., Garkushin I.K. Investigation of the Na+, K+ || VO3–, SO42– ternary reciprocal system and measurement of the nonvariant compositions melting enthalpy. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 6. P. 38-44. DOI: 10.6060/ivkkt.20246706.6983.

Explicating Electrical Conductivity and Melt Structure of the SiO2–MnO–TiO2 Welding Fluxes with Various MnO/TiO2 Mass Ratios

Explicating Electrical Conductivity and Melt Structure of the SiO2–MnO–TiO2 Welding Fluxes with Various MnO/TiO2 Mass Ratios

Effect of fluxes in submerged arc welding for steel: A review

In submerged arc welding, fluxes have a multifaceted function throughout the process of welding. Apart from influencing bead geometry and shielding the weld pool, these fluxes also experience deliberate melting within a defined temperature range. These fluxes serve to refine the weld metal and engage in reactions between slag and metal before ultimately being eliminated as slag. The cost of welding flux constitutes a significant portion of the expenses in the submerged arc welding (SAW) process. As time has passed, the pursuit of improved compositions for welding flux, ones that offer enhanced mechanical properties and productivity while remaining economically efficient, has garnered substantial attention from researchers. This review paper focuses on the collective research efforts of various scholars within the realm of welding flux advancement. The effect of various fluxes on the structural properties of the steel has been briefly revised in this paper.

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.

The Role of Welding Parameters in Hydrogen Embrittlement Mitigation: A Case Study in Steel

This research investigates the mitigation of hydrogen embrittlement in steel, focusing on the effects of metallurgical hydrogen and the efficacy of various reduction techniques. Key findings demonstrate that vacuum treatment during steel casting combined with thermal treatment significantly lowers hydrogen content, enhancing steel's resistance to embrittlement. Welding processes differ in susceptibility to hydrogen-induced cracking, with submerged arc welding (SAW) showing the least and shielded metal arc welding (SMAW) the most susceptibility. Employing multipass welding, along with preheating and post-weld heat treatments, effectively minimizes hydrogen-related cracking by promoting even hydrogen distribution and desorption. The study highlights the successful application of fluoride-ion-containing welding fluxes, such as CaF2 and KF, to reduce weld hydrogen levels through chemical reactions. Furthermore, the choice of welding parameters, particularly the arc voltage, substantially impacts the hydrogen concentration in the welds. Additionally, the incorporation of hydrogen-binding elements such as yttrium significantly reduces the level of free hydrogen, thereby enhancing resistance to hydrogen corrosion. The research underlines the need for selecting appropriate welding methods and parameters to effectively reduce the adverse effects on welded joints. In conclusion, optimizing vacuum and thermal treatments, along with developing innovative welding materials, is imperative to control hydrogen content, crucial to the longevity and reliability of steel products in hydrogen-sensitive applications such as the oil and gas sector.

Impact of incorporating FeNbC into weld flux on the abrasive wear resistance of coatings produced by SAW in a microalloyed steel

Owing to the global shortage of raw materials and an increase in their prices, there is a growing demand for engineering solutions to increase the lifespan and durability of equipment and components. Therefore, this study aims to combine surface engineering and welding engineering to produce a niobium-rich coating using submerged arc welding (SAW) deposition. SAW is a cost-effective technique that allows high deposition rates and technical simplicity, which can enhance mechanical properties and resistance to abrasive wear of components. This research involves the addition of a FeNbC powder alloy in percentages of 5, 10, and 15 wt% to a neutral commercial SAW flux, as an alternative to adding Nb to the microstructure of the deposited coating. The coating was characterized by optical microscopy to analyze the microstructure, such as the presence of phases; microhardness through a Vickers micro-durometer, and resistance to abrasive wear through the loss of mass using a rubber wheel-type abrasometer. The wear mechanisms were evaluated using scanning electron microscopy. The results showed that a Nb-rich coating can be deposited via SAW, and the coatings successfully increased microhardness by up to 110% and resistance to abrasive wear to values higher than the base metal used (microalloyed steel). The microstructure formed was rich in Fe2Nb and NbC, proving the formation of Nb-rich phases. Additionally, the mechanism of abrasive wear was predominantly plastic for the base metal and changed to micro-cutting and micro-plowing after the addition of up to 15% of FeNbC.

Uncovering crystallization mechanisms of SiO2–MnO based welding fluxes

Understanding the crystallization mechanism of flux is critical to tailoring welding processes and thus improving welding performance. However, reproducing or directly observing the flux crystallization process during welding is not feasible due to technical limitations. We report a strategy capturing the crystallization features of SiO2−MnO based fluxes by analyzing post-welding slags. Crystallization mechanisms of the slags have also been elucidated by molecular dynamics simulations and thermodynamic approaches. Our findings reveal that the crystallization fraction is significantly enhanced from 0 to 100% with a substitution of TiO2 for SiO2, but is moderately reduced from 70.68 to 61.96% upon substituting MnO with CaO. Such distinct phenomena have been associated with the fact that crystal nucleation and growth are subjected to thermodynamic and kinetic factors, including degree of structural polymerization, bond distributions, and atomic diffusion capacity. These insights will facilitate tackling practical challenges pertinent to precisely controlling flux crystallization behaviors through compositional adjustment.

EQUIPMENT FOR MECHANISING THE SUBMERGED ARC WELDING PROCESS

Flux welding is a notable, reliable, and adaptable method of combining metals among other welding techniques. Flux welding is an arc welding technique that employs a substance known as "flux" to shield the weld pool from any chemical reactions with atmospheric constituents while welding. Flux materials often comprise borax, hydrochloric acid, or zinc chloride. In the process of flux welding, a joint is covered with a layer of flux, or alternatively, a flux-coated or flux-cored electrode is employed. Upon the formation of the weld pool, the flux undergoes melting and adheres to the pool, thus safeguarding it against any potential reaction with air constituents. This manuscript describes equipment used in mechanized flux welding process in order to improve its performance. Lincoln Electric NA-3N submerged arc welding equipment on a universal lathe longitudinal carriage was designed. The equipment was mounted on a carriage with a maximum longitudinal travel of 2380 mm and a maximum transverse stroke of 410 mm. This carriage moves the welding equipment. The longitudinal advance allows longitudinal and transverse welding on this system.

Влияние режимов дуговой автоматической сварки на геометрические параметры шва стыковых соединений из низкоуглеродистой стали, выполненных с применением экспериментального флюса

Introduction. The metallurgical industry in the territory of the Russian Federation has accumulated a significant amount of slags obtained during the smelting of steels and cast iron. The presence of slag dumps adversely affects the ecology of regions with metallurgical enterprises. When reducing iron from slags, the by-product becomes an oxide agglomerate, which can be considered as a flux composition for arc welding/surfacing under a layer of flux, fillers of powder wires, coatings of welding stick electrodes. The purpose of the work is to establish the possibility of arc welding using the flux obtained by the authors and to determine the optimal welding modes with the condition of achieving the geometric parameters of the seam according to GOST 8713-79 and the quality of the welded joint (absence of internal defects). In this paper, butt welded joints of sheet steel VSt3sp with a thickness of 5 mm obtained by automatic welding under a layer of flux at direct current with forced formation of a root roller on ceramic linings using flux from recycled metallurgical slag of an electric steelmaking enterprise are investigated. Automatic welding of flat specimens was carried out on a tractor-type ADF-1250 machine with a wire with a diameter of 3 mm, at a constant welding speed of 54 cm/min with varying current and arc voltage within 400–600 A and 27–37 V. The methods of investigation: Visual measuring and radiographic control, determination of deformation of specimens by laser scanning and computer processing of 3D models were used to evaluate the quality of welded joints. Statistical modeling in the form of a two-factor experiment was also used in the work, with obtaining adequate regression equations of the influence of welding modes on the geometric parameters of the seam: the height of reinforcement and the width of the seam on the front and back of the joint. Results and discussion. The possibility of obtaining welding fluxes from metallurgical slags of an electric steelmaking enterprise and its use for creating welded joints is shown. Optimal modes of arc welding of thin-walled sheet parts made of low-carbon steel with forced formation of a root roller on ceramic linings is established, ensuring the absence of internal defects in the form of pores, cracks and lacks of penetration, a minimum of residual deformations and compliance of the weld size with the requirements of the existing standard. The nominal values of the geometric parameters of the seam according to GOST 8713-79-C4 correspond to welding mode: welding speed 54 cm/min, welding current 550 A, arc voltage 30 V. The results of the work can be applied in metallurgical electric steelmaking enterprises producing low-carbon steel in the development of technologies for the use of welding materials from slag.

Concurrent reduction of the fume and Cr (VI) concentrations of inhalable and respirable particle using a new covered stainless-steel SMAW electrode

In this work, a new covered electrode was developed for a SMAW process by the concurrent use of two fume reduction techniques viz; nano-arc stabilizer coating on welding core wire and nano-particle substitution on the welding flux. The experimental core electrode wires were coated with nano-zirconium to improve the electrode’s arc stability and reduce the effective oxygen concentration in the arc atmosphere. To further improve the arc stability, size-reduced synthetic rutile was mixed with the electrode flux. Total fume formation from experimental and conventional electrodes was evaluated and compared. Compared to the conventional electrode, the experimental electrode showed an 82 % reduction in fume production and an 85 % reduction in breathing zone concentration. The combined effect of nano zirconia and size-reduced synthetic rutile increased the reactivity of the arc atmosphere and favoured the reduction of inhalable and respirable fume mass concentration by improving arc stability and reducing spatter formation. The experimental electrodes showed a significant reduction in Cr(VI) concentration in fume up to 68 %. The Cr (VI) concentration in the inhalable and respirable fumes was also reduced by 36 % and 52 % in that order.

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.

Key mechanisms and process features of the metal transfer and cavity evolution during underwater submerged arc welding

The key mechanisms and process features of the inner physical processes and quality improvement for the novel underwater submerged arc welding (USAW) were revealed with the employment of X-ray observation. Based on the investigation of metal transfer, cavity, and behaviors of the weld pool and flux in USAW, three kinds of droplet transfer mode were confirmed, namely the indirect transfer, direct transfer, and surface tension transfer, and the proportions of them were 81.8%,12.9% and 5.3%, respectively. Compared with underwater wet welding (UWW), the average droplet transfer period was greatly reduced from 198.5 ms to 102.8 ms, and the mean sizes were also decreased from 3.2 mm to 2.2 mm in USAW. Because far more gases were generated in USAW (4394.2 ml/min) than in UWW (755.7 ml/min), the leading gas flow dragging force acting on the droplet was much stronger in USAW, which repelled the smaller droplet to detach from the wire tip within shorter time than it did in UWW. In addition, smooth and uniform weld seam without obvious defects was produced by USAW, of which the width and reinforcement were increased and reduced by 22% and 14%, respectively. And the 4.6 mm thickness of heat-affected zone for the joint of USAW was 59% wider than that of the UWW joint, indicating the cooling rate was effectively reduced in USAW, which consequently help acquiring sound quality joints in underwater welding.

Elucidating Electrical Conductive Mechanisms for CaF2–SiO2–CaO–TiO2 Welding Fluxes

Elucidating Electrical Conductive Mechanisms for CaF2–SiO2–CaO–TiO2 Welding Fluxes

Development of submerged arc welding flux from rice straw ash

ABSTRACTAt present, a large amount of rice straw ash is being dumped as waste creating soil and water pollution. The manufacturing of welding fluxes requires minerals which are mined out from the earth’s crust creating environmental ill effects. This paper presents a novel methodology for utilizing rice straw ash in the manufacturing of submerged arc welding (SAW) fluxes. The chemical composition of the joints produced with the developed flux is well within the acceptable range of American Welding Society (AWS) specifications. Their tensile strength and joint efficiency are 8% and 9% more than the joints produced with a commercial flux respectively. Their bead geometries are comparable to the beads deposited with the commercial flux. The joints are sufficiently ductile and could easily pass the bend test. The weld metal exhibits a desired microstructure containing acicular ferrite. This technology may turn the rice straw ash into a blessing in disguise.