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This study investigates the microstructure and hardness of weld metals used in liquid hydrogen storage tanks, with a focus on the effects of three welding methods: Gas Tungsten Arc Welding (GTAW), Submerged Arc Welding (SAW), and Shielded Metal Arc Welding (SMAW). Finite element simulations were employed to model the temperature field during welding, aiding in the explanation of observed microstructural differences. The results show that while GTAW and SMAW produce weld metals with similar microstructures, SAW generates significantly larger grains with a pronounced preferential orientation. The use of weaving techniques play a key role in shaping the solidification microstructures. Additionally, the hardness of the weld metal is comparable to that of the base material, with a slight reduction corresponding to increased grain size. This research offers valuable insights into optimizing welding processes for liquid hydrogen storage tanks by addressing the microstructural characteristics that influence weld joint performance. [ABSTRACT FROM AUTHOR]

The creep behaviour of dissimilar weld joint of 316LN SS-P91 steel when subjected to lower applied stresses (below 100 MPa) generally fails in a Type-IV pattern. The dissimilar weld joint was welded through shielded metal arc welding (SMAW) process with INCONEL as electrode, a nickel-based superalloy. An interrupted creep test was carried out at creep condition of 80 MPa −600 °C temperature. Interruption was done at two stages of creep, i.e. (a) mid of secondary and (b) start of tertiary. Microstructural evolution with respect to the hardness variation along various regions of P91 steel at interrupted and the failed specimen was done. A coarsening of hierarchical boundaries and M23C6 carbides was observed along HAZ region that has resulted with respect to time and temperature. [ABSTRACT FROM AUTHOR]

SS316L steel is known as a marine-grade material, which is frequently used in shipbuilding structures and marine industries. In the present study, a shielded metal arc welding (SMAW) process was used for welding of SS316L steel plate by using electrode E316L-16 and E308L-16, welding currents of 70, 80 and 90 A and constant voltages of 24 V. The effect of process parameters on the microstructure and mechanical properties of the welded specimens in the fusion zone (FZ), heat-affected zone (HAZ) and at base has been analysed using scanning electron microscopy (SEM) and microhardness test. The results show that the mechanical properties of the SMAW welded sample are influenced by both electrode properties and applied current. The fusion zone hardness increases compared to the base material. The welded sample processed by using electrode E316L-16 and 80 A current exhibits the higher hardness i.e., 223 HV due to a combination of lower heat input, higher welding speed, and the presence of a fine grain structure compared to other welded sample. A tensile result shows that the Ultimate tensile strength (UTS) of the SMAW welded sample varies from 190 to 262 N/mm2 compared to a base material, i.e., 565 N/mm2. This drop in tensile strength in the welded joints is attributed to HAZ softening stemming from the formation of coarse-grained microstructures. Furthermore, thermal analysis utilizing ANSYS software was employed to assess the influence of heat input at different welding arc times and to map temperature distribution across various plate regions. The results indicate that reducing welding time leads to lower temperatures in the electrode samples, consistent with simulation outcomes. Additionally, variations in microstructure were evident across distinct plate regions. The impact of heat input on microstructural behaviour was further comprehensively examined. [ABSTRACT FROM AUTHOR]

The present investigation is conducted to study the effect of the varying filler composition on microstructure and mechanical properties of the dissimilar metal welds of heat-resistant P92 steel and Ni-based superalloy Inconel 617 used for producing the boiler components in advanced ultrasupercritical (AUSC) power units. The dissimilar joint is prepared using the shielded metal arc welding (SMAW) technique using the electrode metals of Inconel 617 (ENiCrCoMo-1), Inconel 625 (ENiCrMo-3), and Inconel 82 (ENiCrFe-3). All the welds were made with the same welding parameters. It was witnessed from macrostructure and microstructural characterization that there was no evidence of cracks in weldments obtained by Inconel fillers. The EDS observation of the weld showed the presence of Ti(C, N) and NbC in ENiCrFe-3 weld, NbC and laves phase ENiCrMo-3 weld and Cr and Mo-rich phases (M23C6 and Mo6C) in ENiCrCoMo-1 weld. The room temperature tensile test showed the maximum (664 ± 11 MPa) and minimum (590 ± 10 MPa) ultimate tensile strength for the ENiCrCoMo-1 weld and ENiCrFe-3 weld, respectively. However, the ENiCrCoMo-1 weld showed failure from P92 BM, while in the other two welds, failure occurred in the weld metal. The hardness of the weld metal varied from top to root area as well as in transverse direction for each weld joint. The maximum hardness of the weld was 297 ± 12 HV for the ENiCrMo-3 weld and the minimum was 219 ± 9 HV for the ENiCrFe-3 weld. The microstructural characterization and mechanical testing confirmed that ENiCrCoMo-1 filler was the best choice among all the fillers for making the dissimilar joint of P92 and Inconel 617. [ABSTRACT FROM AUTHOR]

The "Author Index Volume 23 (2024)" from the Journal of Advanced Manufacturing Systems provides a comprehensive list of authors and their respective articles published in the journal. The document covers a wide range of topics related to manufacturing systems, including optimization of working parameters, surface roughness prediction, and supply chain evaluation. Authors explore various aspects of manufacturing processes, such as additive manufacturing, machining, and welding, offering insights into advancements and challenges in the field. The index serves as a valuable resource for researchers and professionals interested in the latest developments in advanced manufacturing systems. [Extracted from the article]

This study focuses on achieving enhanced mechanical properties of the welded joints, which is critical for the applications of mild steel (MS) plates in various industries. In this regard, a systematic approach is used to adjust welding parameters such as welding current and workpiece thickness in shielded metal arc welding (SMAW), with the objective of identifying the optimal combination that maximizes weld quality. The experiments were planned with the help of Taguchi's L9 orthogonal array method in order to reduce experimental cost and time. The weld quality is optimized by determining the signal-to-noise ratios of weld penetration, tensile strength, impact strength, and microhardness for each experimental sample. As a result, 110 A welding current is obtained as the optimal SMAW parameter for a 5 mm thick MS IS 2062 Grade B plate. This optimized result has also achieved 394.78 N/mm2 tensile strength and 53 J of impact resistance for the respective specimen. Besides, research not only enhances understanding of the SMAW process but also offers practical implications for industries requiring high-performance welded joints in MS structures. Additionally, this study can assist upcoming researchers in optimizing any existing welding procedures. [ABSTRACT FROM AUTHOR]

The synthesis of special photocatalysts of nanostructured functional ceramics (PNFC) under the ZKHM brand under the influence of concentrated solar radiation showed the effectiveness of these ceramic materials in multifunctional use, in particular as additives for coatings of welding electrodes. However, problems with producing these materials in solar ovens on an industrial scale did not allow the widespread use of this method. This problem was solved using the technique of PNFC synthesis, followed by activation by pulsed radiation generated by functional ceramics. The ceramic material obtained by this method under the brand name ZB-1 also showed its effectiveness when used as an additive in welding electrode coatings. A comparative analysis of the effectiveness of the actions of additives from the ZKHM and ZB-1 brands on the welding and technological properties of welding electrodes from the MR-3 brand was carried out. Comparative results for the formation of weld beads showed that beads with high-quality formation without external defects were achieved when surfaced with electrodes with additives from both brands at concentrations up to 1%. Also, at concentrations up to 1%, these additives increased the breaking length of the arc and the stability of arc welding. The different effects of these additives were observed in a comparative analysis of their impacts on the size of the visor at the end of the electrode, the coefficients of melting and surfacing, and the loss factor for fumes and splashing of electrode metal. [ABSTRACT FROM AUTHOR]

Welding is a crucial process in joining metals, especially in the fabrication industry. Thisresearch aimed to investigate the effects of using two different filler materials, ER70S-6 and ER308LSi, with nine combinations of wire feeder speed (WFS) and shielding gas flow rate (GFR), on weld joints. The study focused on the weld quality and material properties of Gas Metal Arc Welded (GMAW) butt joints of ASTM A516 G70 plates, characterized through visual inspection, liquid penetrant testing, tensile testing, hardness testing, and optical microscopy. Results indicated that the highest ultimate tensile strength and hardness were achieved at 4 m/min WFS and 15 L/min GFR with ER70S-6, and 5 m/min WFS and 20 L/min GFR with ER308LSi. The specimens welded with ER308LSi demonstrated superior mechanical properties compared to those welded with ER70S-6. Additionally, the study revealed the influence of microstructural changes from the base metal (BM) to the heat-affected zone (HAZ) and fusion zone (FZ), with finer and more compact grain structures contributing to higher hardness values. These findings underscore the importance of selecting appropriate filler materials, WFS, and GFR to achieve the desired weld quality and material properties for A516 G70 low-carbon steel welded joints. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to assess the pitting resistance of austenitic stainless steel welded joints fusion zone (FZ) with high density of inclusions before and after surface treatment, including potentiostatic pulse technique (PPT) and pickling. Design/methodology/approach: The potentiodynamic polarization tests and critical pitting temperature tests were carried out for estimating pitting resistance. The PPT and pickling were performed as surface treatment. Scanning electron microscope (SEM) and energy dispersive spectrometer were used for characterize the microstructure and elemental distribution. Electron back-scattered diffraction (EBSD) was used to assess the portion of phases and morphology of grains. Findings: The weld metal exhibits a higher degree of alloying compared to the base metal, and it contains d-phase and sulfur-containing inclusions. Sulfur-containing inclusions serve as initiation sites for pitting, and they diminish the pitting resistance of weld metal. Both PPT and pickling can remove sulfur-containing inclusions, but PPT causes localized dissolution of the weld metal matrix around the inclusions, while pickling does not. Because of the high density of inclusions, certain pits initiated by PPT are significantly deeper, which makes the formation of stable pitting easier. Because of the high density of inclusions, certain pits initiated by the PPT are deeper. This characteristic facilitates the progression of these initial defects into fully developed, stable pits. Originality/value: Analysis of pitting initiation in shielded metal arc welding FZ with PPT and ex situ SEM tracking observation. Explanation of why the PPT surface treatment is not able to enhance the pitting resistance of stainless steel with a high inclusion density. [ABSTRACT FROM AUTHOR]

Dissimilar metal welded (DMW) joint plays a crucial role in constructing and maintaining ultra-supercritical (USC) nuclear power plants while presenting noteworthy environmental implications. This research examines different welding techniques utilized in DMWJ, specifically emphasizing materials such as P91. The study investigates the mechanical properties of these materials, the impact of alloying elements, the notable difficulties encountered with industrial materials, and the concept of buttering. The USC nuclear power plants necessitate welding procedures appropriate for the fusion of diverse metal alloys. Frequently employed methodologies encompass shielded metal arc welding (SMAW), gas tungsten arc welding (GTAW), gas metal arc welding (GMAW), and flux-cored arc welding (FCAW). Every individual process possesses distinct advantages and limitations, and the choice of process is contingent upon various factors, including joint configuration, material properties, and the desired weld quality. The steel alloy known as P91, which possesses high strength and resistance to creep, is extensively employed in advanced ultra-supercritical (AUSC) power plants. P91 demonstrates exceptional mechanical characteristics, encompassing elevated-temperature strength, commendable thermal conductivity, and notable resistance against corrosion and oxidation. The presence of alloying elements, namely chromium, molybdenum, and vanadium, in P91, is responsible for its improved characteristics and appropriateness for utilization in (AUSC) power plant applications. Nevertheless, the utilization of industrial materials in DMW joint is accompanied by many noteworthy concerns, such as the propensity for stress corrosion cracking (SCC), hydrogen embrittlement, and creep deformation under high temperatures. The challenges mentioned above require meticulous material selection, process optimization, and rigorous quality control measures to guarantee the dependability and sustained effectiveness of DMW joint. To tackle these concerns, a commonly utilized approach referred to as buttering is frequently employed. When forming DMW joint in nuclear facilities, it is customary to place a buttering coating on ferritic steel. This facilitates the connection between pressure vessel components of ferritic steel and pipes of austenitic stainless steel. The primary difficulty in DMW joint manufacturing is in mitigating the significant disparity in material characteristics resulting from carbon migration and metallurgical alterations along the fusion interface between ferritic steel and austenitic stainless steel. The process of buttering entails the application of a compatible filler material onto the base metal before the deposition of the desired weld metal. The intermediate layer serves as a mediator, enhancing the metallurgical compatibility, diminishing the probability of fracture, and enhancing the overall integrity of the joint. Buttering is still a new research area with a wide scenario of scope in terms of development, which could revolutionize developing high-temperature. These long-term sustainable joints could serve under critical conditions like AUSC power plants and reduce CO2 emissions by increasing the overall efficiencies of the systems. [ABSTRACT FROM AUTHOR]

This research paper investigates the effectiveness of shielded metal arc welding (SMAW) and flux‐cored arc welding (FCAW) on mild steel substrates for chromium–boron hardfacing. Chromium–boron alloys are hard‐wearing and corrosion‐resistant materials used in industries where wear resistance is critical. The study aims to identify the best welding technique for increasing surface hardness and wear resistance. Standard test specimens were chosen and deposited using SMAW and FCAW processes. SMAW uses an electrode covered with flux, which turns into a sticky state when heated, while FCAW uses a core wire fabricated from flux, which generates a shielded gas upon melting. The effectiveness of each welding technique is assessed based on deposition efficiency, dilution rate, microstructure, hardness distribution, and wear resistance. This research helps industries choose the most efficient material and method for improving wear and corrosion resistance in applications like mining, construction, agriculture, and manufacturing. On average, FCAW offers a 1.67% improvement in hardness and 28.12% improvement in mass loss reduction when compared to SMAW. [ABSTRACT FROM AUTHOR]

The surface morphology influenced the corrosion resistance, which depended on the welding process and its parameters. In this study, we investigated the relevance of the welding process that produces excellent mechanical properties and corrosion resistance, which gives the best working performance for carbon steel pipes that transfer refined oil products in an Iraq oil refinery. AISI 1020-A106 carbon steel pipes are welded using shielded metal arc welding (SMAW) and gas tungsten arc welding (GTAW). Electrochemical corrosion tests were performed in 3.5% NaCl and immersion tests in heavy Naphtha at 50, 75, and 100 °C. The results show that retained austenite, ferrite, pearlite, and martensite phases are produced after the SMAW process. In contrast, ferrite, pearlite, and a small amount of martensite are produced after GTAW. The ultimate tensile strength of the SMAW samples was higher than those of the GTAW samples, but the GTAW samples had higher fracture elongation, and all samples had no cracks in the welding area during the bending test. The electrochemical and immersion corrosion rates of the samples welded with SMAW are higher than those welded with GTAW. The corrosion rate increases when the naphtha temperature increases and has a higher and unacceptable value at 100 °C. [ABSTRACT FROM AUTHOR]

The coating fluxes used in SMAW electrodes for nuclear power plants have been specially developed. The study investigates various characteristics such as floatation coefficient, work of adhesion, spread area, and contact angle at a high temperature of 1323 K. The flux compositions, comprising Na3AlF6–CaO–Al2O3–SiO2, are developed using the extreme vertices design approach, resulting in 26 different compositions. Furthermore, the surface tension of these fluxes was calculated as part of the investigation. Regression analysis was employed to predict the influence of individual constituents and their interactions on the wettability properties of the flux coatings. Additionally, artificial neural network (ANN) models were developed and compared to regression analysis to assess prediction accuracy. The fluxes underwent further characterization through X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analysis to identify the phases present. The structural analysis of the molten slag was conducted by examining the powdered samples obtained through quenching. The FTIR results indicate the presence of [SiO4]4− tetrahedral units and [AlO4]5− tetrahedral units, suggesting the formation of a network structure. Additionally, it is observed that CaO acts as a network breaker, causing the release of non-bridging oxygen (O−) at the expense of bridging oxygen (O0). The individual components CaO, Na3AlF6, Al2O3, and SiO2 were found to cause a decreased effect, while the binary interaction of the coating constituents shows a significant effect on the contact angle and floatation Coefficient. Individual interactions, CaO, SiO2, Al2O3, and Na3AlF6 exhibit a positive impact, while the binary interactions of Na3AlF6·SiO2, Na3AlF6·Al2O3, CaO·Na3AlF6, Al2O3·SiO2, CaO·SiO2, and CaO·Al2O3 have been found to have a decreasing effect on the spread area and work of adhesion. [ABSTRACT FROM AUTHOR]

This work discusses the effect of gas tungsten arc welding (GTAW) variables on the welding transverse tensile strength and hardness of S 235JR at different groove configurations. The welding microstructure and numerical fracture mechanism are also discussed. GTAW is increasingly emerging in the local industry due to its advantages over conventional shielded metal arc welding (SMAW). The properties of steel welding have always concerned manufacturers and researchers. Since steel structures experience forces such as tensile, it's vital that good welding has increased tensile strength. It was reported that the hardness of welding affects the welding properties and, therefore, the integration of welded structures. The groove shape of the joining ends determines the size of the FZ and affects the dilution; thus, it is important to study the groove shape due to its effect on the final properties of welding. The results showed an increased welding traverse tensile strength (251 MPa) at higher welding speeds (150 mm/min) and V-shaped groove welding. The Vshaped groove welding that obtained higher tensile strength (251 MPa) has shown higher grain boundary ferrite and PF volume friction in the FZ and finer PF in the HAZ due to its higher interpass heat input. Higher traverse tensile strength welding has shown increased bainite and lower bainite volume friction in FZ and a finer grain structure in HAZ. The failure due to tensile force starts at the welding root, according to numerical analysis, and a double V-shaped groove has shown deformation balance at the tensile test. [ABSTRACT FROM AUTHOR]

Technological equipment in quarries that extract and deliver aggregates for different uses operates in a predetermined flow depending on the type of rocks exploited and the dimensional characteristics imposed on the final products. In this context, the interruptions in operation required to replace high-wear parts (such as the teeth of excavators and bucket loaders) must be limited as much as possible through technological solutions to increase their service life. The evolution of the wear of the teeth of the quarry equipment that come into direct contact with rocks was concretely established in the production process, in parallel with the wear values obtained by simulating the wear phenomenon in laboratory conditions, in order to validate the data collected during the operation of the machines. Preventive–repetitive maintenance within the activities of reconditioning the worn surfaces of the teeth, through the charging process by manual electric welding with covered electrodes, was applied directly to the machine, which led to the shortening of the interruptions in operation necessary to replace these spare parts. [ABSTRACT FROM AUTHOR]

Nowadays, low alloy steels effectively contribute to the manufacture of several important products, thus welding these types of steel is of great importance. Two different common welding processes, namely SMAW and OAW using two different fillers (E6013 electrode and A5.2 RG45 wire respectively) were employed to join 6 mm thick AISI 5160 low alloy steel plates. Compared to SMAW, the OAW process resulted in much wider HAZ. Microscopy of both welds revealed that the structure of the weld metal was generally ferrite and pearlite, while that of the unaffected base metal was predominantly pearlite. The structure in the fusion zone and CGHAZ of the oxy-acetylene weld was coarser than that of the SMA weld. Nevertheless, the hardness values across the oxy-acetylene weld were generally lower than those found across the SMA weld. The highest hardness across both welds was in the CGHAZ, while the lowest was in the inter-critical HAZ, and the average hardness in the weld center was lower than that of the base metal. Finally, the average tensile strength value of the SMA weld was much higher than that of the oxyacetylene weld, where fractography observation revealed porosity and an oxide layer, and the fracture was brittle. [ABSTRACT FROM AUTHOR]

The effects of the post weld heat treatment (PWHT) on the microstructure and hardness of the underwater wet welding (UWW) SS400 steel have been evaluated. The UWW was performed using Shielded Metal Arc Welding (SMAW) in water depth of 5.0 m, while PWHT was carried out on underwater welded specimen with temperature of 660 oC for 75 minutes. The result showed that the PWHT caused increasing the grain size of the microstructure and decreasing in hardness. [ABSTRACT FROM AUTHOR]

The welding has been utilized to stabilize the phase fractions in the microstructure of lean duplex stainless steel (LDSS) to build massive mechanical structures. The influence of heat input on the microstructure, mechanical properties, and corrosion behavior of LDSS 2101 during the gas tungsten arc welding (GTAW) and shielded metal arc welding (SMAW) processes is investigated in the present work. Specifically, we compared the outcomes between low heat input (LHI) at 0.85 kJ/mm and high heat input (HHI) at 1.3 kJ/mm for both welding techniques. Throughout the welding process, ER2209 filler wire was utilized. To assess the microstructural changes in the weldments, we employed an optical microscope, a scanning electron microscope, and X-ray diffraction. The results revealed that the volume phase fraction of ferrite was significantly higher in the LHI sample of GTAW compared to HHI GTAW and all SMAW welds. LHI GTAW welds have 18.2% greater Charpy impact toughness than LHI SMAW, whereas HHI GTAW has 35.7% higher than HHI SMAW specimens. The microhardness of the LHI GTAW weldments increased (from 230 ± 3.2 to 252 ± 4.8 HV10), whereas the microhardness of the LHI SMAW weldments increased (from 227 ± 2.8 to 246 ± 5.2 HV10). GTAW exhibited a fine grain structure, showcasing favorable tensile properties and higher hardness compared to SMAW. Conversely, the SMAW welds and their heat-affected regions exhibited coarse grain structures. These findings highlight the superior performance of GTAW in terms of microstructural characteristics, and mechanical properties when working with LD SS 2101 in comparison to SMAW.

In the fabrication industry, selecting the most suitable welding method is crucial for optimizing standard work hours (SWH) and achieving efficient resource utilization. This study aims to provide a systematic evaluation of three prevalent welding techniques--Gas Metal Arc Welding (GMAW), Shielded Metal Arc Welding (SMAW), and Gas Tungsten Arc Welding (GTAW)--using the Simple Multi-Attribute Rating Technique (SMART). The objective is to identify the welding method that best balances efficiency, complexity, weld volume, and skill requirements. The methodology involves evaluating the three welding methods based on five key criteria: Labour Efficiency (LE), Operational Efficiency (OE), Job Weight, Weld Volume, and Skill Level. Each criterion is assigned a relative weight to reflect its importance in the overall evaluation. The SMART technique is employed to aggregate these weights and assess the performance of each welding method against the criteria. The findings reveal that GMAW stands out as the most effective welding method when considering the balance of efficiency, complexity, weld volume, and required skill level. GMAW's performance surpasses that of SMAW and GTAW in terms of overall suitability for most fabrication tasks. The study concludes that GMAW is optimal for enhancing productivity and resource management in the fabrication industry. Future research could expand on this study by incorporating additional criteria that might affect welding performance, such as environmental impact or cost considerations. Additionally, applying alternative multicriteria decision-making techniques could provide further validation of the results and offer a more comprehensive analysis of the welding methods. This would enable a more nuanced understanding of the trade-offs between different welding techniques and their applicability to various industrial contexts. [ABSTRACT FROM AUTHOR]

Steel pipelines used for oil and gas transmission are at risk of stress corrosion cracking (SCC). Extensive research has been carried out to evaluate the SCC susceptibility of pipeline steels. Those research studies were mainly specific to the steels of pipes without welding. In this research, pieces of X65 steel plates were welded by the shielded metal arc welding process. The speeds of electrode travel were set as the main welding parameter. Slow strain rate tests (SSRTs) in the air and the NS4 standard solution were conducted. The results showed that the tensile behavior of the samples in the solution was very different from that in the air. For the samples tested in the solution, the strength amounts of the weld zones were higher than the strength of the base metal, but in the case of SSRT in the air, the strength of the base metal was higher. As a result, the UTS strength of one of the weld zones reached levels as high as 480 MPa and also 34% elongation under the SSRT. Therefore, the conditions of welding have a high degree of importance and must be controlled to have less SCC susceptibility. [ABSTRACT FROM AUTHOR]

Non-destructive testing (NDT) denotes a collection of non-invasive inspection techniques employed to evaluate the properties of materials, components, and entire process units. NDT techniques are applicable for several types of inspections. Welds are among the most often inspected components of industrial assets. Inspectors can determine the robustness of a weld or identify any defects that may compromise its integrity with non-destructive weld testing apparatus. Welding is a crucial procedure in the metal fabrication sector. This research used Dye Penetrant Testing (DPT), a non-destructive testing technique, to examine the welding. This study aims to examine defects in Shielded Metal Arc Welding (SMAW) via Dye Penetrant Testing (DPT) and to optimize SMAW parameters for improved results in accordance with American Society of Mechanical Engineers (ASME) standards. The study identified two types of defects: porosity and cracks; however, porosity was selected for analysis. The Taguchi Method served as the optimization technique for welding parameters. The design summary employed the L9 orthogonal array, considering two factors: the welding current and the thickness of the mild steel plate sample. The signal-to-noise ratios were configured to prioritize lower values, as the objective is to achieve the minimum output to minimize welding defects. The link between porosity, welding current, and sample thickness indicates that a higher welding current applied to a thicker sample result in fewer porosity flaws. Applying the highest welding current to the sample with lower thickness will result in more porosity flaws. The optimal parameters for minimizing porosity in the welded specimen are a current of 100 A and a thickness of 6 mm. [ABSTRACT FROM AUTHOR]

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AbstractVibration assisted welding has gained popularity over the years for creating high quality welds and achieving better mechanical properties. The main objective of this research is to use low frequency vibration-assisted welding to optimise the process parameters. This study uses a novel vibratory technique to vibrate the workpiece during shielded metal arc welding at frequencies ranging from 0 to 100 Hz in order to examine the hardness of mild steel plates butt-welded to a thickness of 5 mm. Taguchi Methodology has been applied to optimise the hardness of welded specimens by varying the input variables viz. Current, vibration duration, and vibration frequency. Additionally, the microstructure of welded mild steel plates has been studied using SEM, optical micrographs, and XRD analysis. Results indicated that a low heat input of 80 Amp frequency of vibration of 100 Hz, and duration of vibration of 100 sec demonstrated optimum performance in terms of hardness of welded MS plates. Frequency of vibration has been found to be the most important parameter determining the hardness of the welded joint. Maximum hardness of 97.1643RHN has been found at optimal parameters. As the weld pool is being excited, vibration-assisted welded butt joints exhibit a finer grain structure, suggesting higher hardness values. [ABSTRACT FROM AUTHOR]

Unforeseen failures in girth welds present a significant challenge for the pipeline industry. This study utilizes 3D Digital Image Correlation (DIC) assisted cross-weld tensile testing to analyze the strain response of high-strength thick-walled pipelines, providing essential insights into the strain migration and fracture mechanisms specific to girth welds. The results reveal that the welding process significantly affects the mechanical distribution within the girth weld. The tested Shielded Metal Arc Welded (SMAW-ed) pipe exhibited undermatched girth welds due to high heat input, while Gas Metal Arc Welding (GMAW) introduced a narrower weld and Heat-Affected Zone (HAZ) with higher hardness than the base metal, indicative of overmatched girth welds. Strain migration, resulting from a combination of metallurgical heterogeneous materials and geometrical reinforcement strengthening, progressed from the softer HAZ to the base metal in the SMAW-ed sample with reinforcement, ultimately leading to fracture in the base metal. In contrast, the GMAW-ed sample shows no strain migration. Reinforcement significantly improves the tensile strength of girth welds and effectively prevents failure in the weld region. Sufficient reinforcement is crucial for minimizing the risk of failure in critical areas such as the weld metal and HAZ, particularly in SMAW-ed pipes. [ABSTRACT FROM AUTHOR]

This research investigates the impact of root pass removal procedures, specifically back grinding and back gouging, on the mechanical and microstructural properties of mild steel joints welded through shielded metal arc welding (SMAW). The study employs ASTM A516 grade 70 base metal and E7018 electrode, providing detailed information on welding parameters, joint preparation, and testing methods. Microstructural analysis indicates that the back-gouged joint, with higher heat input, exhibits coarser grains in heat-affected and fusion zones compared to the back-ground joint. Tensile tests reveal superior mechanical properties in the back-ground joint, attributed to grain refinement. Charpy impact tests highlight a 9.5% reduction in impact toughness for the back-gouged joint associated with coarser grains. Microhardness profiles support these findings, emphasizing the importance of welding parameters in achieving desired microstructural outcomes and mechanical performance. The research contributes valuable insights for optimizing welding processes and improving the integrity of welded joints. [ABSTRACT FROM AUTHOR]

In this investigation, Ultra-high Hard Armor (UHA) steel plate by Shielded Metal Arc Welding (SMAW) process using the Austenitic Stainless Steel (ASS) electrode. In the first part of this investigation, using the finite element method (FEM), thermal analysis parameters were optimized using bead on plate welds in software code, known as SYSWELD. In the second part, using optimized parameters, a coupled thermo-mechanical analysis on multipass welded fabrication was carried out. Weld thermal cycles were analyzed by simulation and compared with experimentally measured temperature profiles. A double ellipsoidal heat source model was used to simulate the SMAW process. The heating rate and cooling rate were calculated along with residual stresses. This range of heating and cooling rate resulted in untempered martensite in the heat-affected zone (HAZ), confirmed by microstructure analysis and hardness mapping. Good validation was found between the measured and simulated 2D model with a 4–10% variation. This study suggests that numerical simulation is the capable technique in understanding the thermal and mechanical properties that influence the welding of ultra-high hard armor steels joints. [ABSTRACT FROM AUTHOR]

Marine structures such as ports, bridges, pipelines, vessels, and platforms are an essential part of modern infrastructure, where the use of higher-strength steel provides savings in logistics and construction. However, the repair of higher-strength steels can be challenging, especially underwater. Wet shielded metal arc welding is the most widely used and least expensive method for underwater welding repairs, but is very susceptible to hydrogen-induced cracking. Thus, researchers and welding engineers aim to reduce the amount of hydrogen in the weld material. Recent success has been achieved through the use of austenitic welding consumables, such as austenitic stainless steel and nickel-based electrodes. The use of these consumables drastically reduces the amount of diffusible hydrogen in the weld metal. However, these austenitic materials usually have different corrosion potential as compared to the structural steel the weld beads are applied to. This creates the risk of severe galvanic corrosion. In the presented study, the corrosion behavior of welds created with austenitic stainless steel and nickel-based electrodes were studied. Samples were aged for 1.5 years in the Baltic Sea. Simultaneously, the effectiveness of corrosion protection systems such as coating and Impressed Current Cathodic Protection (ICCP) were evaluated. Localized corrosion occurred in the heat-affected zone when austenitic electrodes were used in the corrosive environment. The localized corrosion depth after 1.5 years in the Baltic Sea and in the salt spray layer was approximately 250 µm and 390 µm, respectively. The ICCP system and the use of a coating were effective in preventing localized corrosion. The low pitting corrosion density of 2.5 × 103 m−2 corresponds to grade A1 according to the standard and was found to be negligible as compared to the localized corrosion in the heat-affect zone. [ABSTRACT FROM AUTHOR]

Vibration-assisted welding has evolved as a high-quality weld-production technology. Researchers have recently adopted medium and high frequency assisted welding to improve mechanical qualities. The primary goal of this research is to investigate and optimize process parameters while employing low frequency vibration-assisted welding. The impact strength of 5 mm thick butt-welded MS plates is investigated in this study, employing a novel vibratory approach to impart vibration to the workpiece at frequencies ranging from 150 to 250 Hz during shielded metal arc welding. The Taguchi approach has been used to optimize the process parameters viz. Current, vibration time, and vibration frequency on the impact strength of welded specimens. SEM analysis was also used to examine the microstructure of welded MS plates. The results showed that a low heat input of 81 Amp, a frequency of vibration of 171.97 Hz, and a period of vibration of 110.45 s provided the most effective performance in terms of welded MS plate impact strength. The frequency of vibration has been discovered to be the most crucial characteristic affecting the toughness of the welded joint. For LFVW welded butt joints, a fine grain structure is seen, suggesting enhanced impact strength values owing to weld pool excitation. [ABSTRACT FROM AUTHOR]

Recently, low alloy steel types have been widely utilized in the manufacture of many important products, which may be damaged during service and require repair by welding. Shielded metal arc welding of 6 mm thick AISI 5155 low alloy steel plates with different electrodes was employed to examine and compare the microstructure and mechanical properties of the welds. The results showed diverse microstructures over the weld metals. The maximum hardness values across the welds were in the CGHAZ, where the structure contained ferrite and pearlite coarser than that of the base metal. The finest structure was in the inter-critical HAZ, in which the minimum hardness was; where partial spheroidization of pearlite occurred. The average weld metal hardness value, for all welds, was lower than that of the base metal (-465 HV). The highest hardness value was (-337 HV) for the weld produced using the OK48.00 electrode, whilst the maximum tensile strength was (938 MPa) for the weld due to the use of the OK76.18 electrode. The low cost electrode (OK46.00) and the expensive one (OK92.18) gave relatively lower mechanical properties, whereas the optimum properties were achieved as a result of using iron powder low hydrogen covering electrodes (OK48.00 and OK76.18). [ABSTRACT FROM AUTHOR]

The welding has been utilized to stabilize the phase fractions in the microstructure of lean duplex stainless steel (LDSS) to build massive mechanical structures. The influence of heat input on the microstructure, mechanical properties, and corrosion behavior of LDSS 2101 during the gas tungsten arc welding (GTAW) and shielded metal arc welding (SMAW) processes is investigated in the present work. Specifically, we compared the outcomes between low heat input (LHI) at 0.85 kJ/mm and high heat input (HHI) at 1.3 kJ/mm for both welding techniques. Throughout the welding process, ER2209 filler wire was utilized. To assess the microstructural changes in the weldments, we employed an optical microscope, a scanning electron microscope, and X-ray diffraction. The results revealed that the volume phase fraction of ferrite was significantly higher in the LHI sample of GTAW compared to HHI GTAW and all SMAW welds. LHI GTAW welds have 18.2% greater Charpy impact toughness than LHI SMAW, whereas HHI GTAW has 35.7% higher than HHI SMAW specimens. The microhardness of the LHI GTAW weldments increased (from 230 ± 3.2 to 252 ± 4.8 HV10), whereas the microhardness of the LHI SMAW weldments increased (from 227 ± 2.8 to 246 ± 5.2 HV10). GTAW exhibited a fine grain structure, showcasing favorable tensile properties and higher hardness compared to SMAW. Conversely, the SMAW welds and their heat-affected regions exhibited coarse grain structures. These findings highlight the superior performance of GTAW in terms of microstructural characteristics, and mechanical properties when working with LD SS 2101 in comparison to SMAW. [ABSTRACT FROM AUTHOR]

This research work investigates the impact of different welding processes i.e., Shield metal arc welding (SMAW), Gas metal arc welding (GMAW), and Flux core arc welding (FCAW) technique on the fracture toughness of API X60 pipeline steel. Utilizing Charpy V-notch (CVN) testing, the impact toughness of the base metal (BM), heat-affected zone (HAZ), and weld zone (WZ) was measured across a range of temperatures from -196°C to 20°C. The analysis reveals that different welding methods and the heat input associated with each significantly affect the fracture properties of the steel. The SMAW process shows the most considerable decrease in energy absorption in the HAZ, especially at lower temperatures, indicating a significant impact on the material's toughness. Conversely, GMAW demonstrates the lowest reduction and the highest increase in toughness in the HAZ and WZ, respectively, making it a superior method in maintaining material integrity during welding. The FCAW method exhibited a moderate and variable behavior in toughness changes, suggesting its intermediate effectiveness. The study further identifies that the chemical composition of the welding electrodes, particularly those containing nickel has a crucial part in enhancing the toughness of the welded zones. Additionally, it underscores the importance of understanding the microstructural changes induced by varying heat inputs, which directly influence the fracture behavior and lifespan of pipeline steels under low-temperature conditions. These findings are essential for improving welding practices and material selection in an ensuring safer, and economical transportation solutions for hydrocarbons over long distances. [ABSTRACT FROM AUTHOR]

Damage evolution in a creep tested 316LN stainless steel—P91 steel dissimilar weld joint fabricated by shielded metal arc welding has been investigated. Failure in this joint which was tested at 873 K and stress level of 80 MPa occurred by Type IV cracking in the P91 steel's heat-affected zone. Microstructural investigation on the failed specimen revealed presence of creep cavities adjacent to the fractured region. To get an insight of failure mechanism, orientation imaging microscopic analysis was carried out on the fractured and two interrupted creep tested specimens—one tested up to onset of apparent secondary regime and another up to the onset of apparent tertiary regime. The analysis established that the damage associated with creep cavitation was more prevalent in the fine-grained heat-affected zone (FGHAZ) and that nucleated cavities in this region were resolvable after onset of the apparent tertiary regime. Though cavities were observed in the inter-critical heat-affected zone after exposure up to onset of tertiary, their growth was not significant. The weakening of the FGHAZ's microstructure is attributed to extensive precipitation and coarsening of M23C6 in this region. Kernel Average Misorientation studies revealed that the dislocation substructure did not alter considerably in both the regions until the onset of the apparent secondary regime. However, after subsequent exposure damage evolution was quite different in both these regions. Based on the microstructural findings a new failure mechanism has been proposed describing the preferential damage in the investigated dissimilar weld joint during creep. [ABSTRACT FROM AUTHOR]

The effect of weld chemistry (two types of electrodes (E2594 and E2595)) on the microstructure and texture development using electron back scattered diffraction and thermal stability during shielded metal arc welding of alloy 2507 have been studied. Base metal showed alternate bands of austenite (γ) and ferrite (δ) in almost equal fractions. Weldments were mainly comprised of 3 zones, namely base metal zone (BMZ), heat affected zone (HAZ), and weld metal zone (WMZ). After welding, ferritic solidification mode was found with diverse morphologies of austenite viz. grain boundary austenite, Widmanstatten austenite, and intergranular austenite and a decrease in the fraction of austenite in WMZ and HAZ. The texture intensity of δ was observed to be higher than that of γ. This implies a stronger texture for δ (a strong rotated cube texture 001 110 along with minor α-fibre rolling direction , RD / / 110 and γ-fibre normal direction , ND / / 111 ) than γ [Brass, Cu, Goss and S texture components ( 110 112 , 112 111 , 110 001 and 123 634 , respectively)] in the annealed state (BMZ). γ/δ grains showed the Kurdjumov–Sachs (K–S) orientation relationship. Kernel average misorientation (KAM) graphs/maps showed no significant change in BMZ but a substantial decrease in KAM values in δ than γ for both weldments. The peak temperature attained was sufficiently higher than the melting temperature of base/filler metal suggesting the proper melting and diffusion of molten metal throughout the thickness. The size of the melt pool widened for E2594 and was relatively small for E2595. [ABSTRACT FROM AUTHOR]

Hardfacing is commonly used in parts recovery and in obtaining surfaces with improved properties. Within this field, it is important to analyze the effect of alloying elements on the properties of the deposited layers. One of the critical parameters affecting alloying performances in SMAW is improper arc length. This article examines the effect of the addition of niobium in different quantities (0, 2, 4, 6, and 8% by weight) to the electrode coating in Fe-Cr-C shielded metal arc welding (SMAW), with short and long arc lengths, on the operational process efficiency, dilution, arc energy, microstructure, and microhardness of the deposited layers. A decrease in operational process efficiency and dilution was found with increases in niobium content. On the other hand, it was found that adding niobium leads to a refinement in chromium carbide sizes, directly affecting the hardness of the obtained deposits. There is a direct relationship between the arc energy, with both short and long arc lengths, leading to a tendency to decrease the dilution in the obtained hardfacing. [ABSTRACT FROM AUTHOR]

Strain gradient plasticity phenomenon in the parent material (PM), heat affected zone (HAZ) and fusion zone (FZ) of butt and lap joint of shielded metal arc welded AISI A36 steel is studied. The deformation mechanisms of the weldment were explained using mechanistic and phenomenological plasticity and dislocation models. The hardness of the FZ and HAZ of the lap weldment were 1.83 GPa and 1.56 GPa, which were slightly higher than the 1.63 GPa and 1.49 GPa of the FZ and HAZ of the butt. Tensile strengths of the butt joint was ∼384 MPa and that of lap was ∼361 MPa, which were higher than the parent material of ∼290 MPa. The difference in strength between the butt and lap joint were due to the weld configuration and the limited fusion of the single build of the lap joint. The material length scale parameters varied due to microstructural transition from the PM to the FZ as a function of temperature. Length scales of ∼34.37 μm and 22.75 μm were observed for the fusion zones of the lap and butt joints, whereas the lowest of 14.76 μm was for the as-received A36 steel. The geometrically necessary and statistically stored dislocations densities were higher in the lap weldment than for the butt. The average shear strain estimations were used to elucidate the underlying dislocation structures and densities. Grain refinement and localised stress and strain states at the HAZ and FZ led to variations in the mechanical properties. The implications of the results for robust design of welds for structural applications are discussed.

A new filler metal was developed to join the new generation weathering steel Q690qNH. Microstructural evolutions and the associated mechanical behavior of weldments were comparatively studied in hot rolled and tempered thick Q690qNH plates with initial microstructure of lath bainite and granular bainite respectively. Phase transformations in the HAZ promote the work hardening capacity of the weld jointed tempered Q690qNH (Q690T) plate and enable the joints to exhibit a different mechanical response upon the tensile loading in comparison to the weld jointed hot rolled Q690qNH (Q690R) plate. Prior austenite reconstruction was carried out to understand the crack nucleation behavior in HAZ. The plastic incompatibility between martensitic-austenitic (M-A) and bainitic ferrite leads to the nucleation of plastic micro-voids from the prior austenite grain boundary or M-A boundary. The fracture of Q690R joint is caused by coalescing micro-voids in HAZ with a strength reduction of 10%–14% that caused by the welding process. The continuous yielding behavior regarding the retained austinite in HAZ results in a competition of the plastic deformation in each subzone of the Q690T joint, of which the catastrophic fracture is dominated by the initial microstructure comprising the ferrite and the granular bainite.

Shielded metal arc welding (SMAW) is one of the most important processes of joining two metals or materials because of its high efficiency and low time requirement. This work studied the tensile strength of SMAW dissimilar mild steel (MS) and medium carbon steel (CS) with various process variables such as Welding Current (WC), Electrode Angle (EA), and Root Face (RF). The chosen variable ranges are WC of 140,180 and 200Amp, EA of 30,45 and 60 degrees and RF of 1,2 and 3 mm respectively to identify the important variables on Tensile strength (TS). Design of experiments (DOE) is executed as per Taguchi L9 OA for recognizing the optimal level of variables to accomplish maximum tensile strength. The experimental result is witnessed that the highest TS (201.38 MPa) is attained at sample-8 when WC −140 Amp, EA-45 degree and RF-1mm are maintained whereas the lowest TS (41.61 MPa) is obtained at sample-9 due to increment of the electrode angle (60 degree) and root face (2 mm), Analysis of variance result is revealed that Electrode Angle is the most important variable (73.97%) which improves TS of the SMAW joints, followed by Root face (6.24%) and Welding current (5.12%). [ABSTRACT FROM AUTHOR]

The SA516 Gr.70 steel possessing excellent toughness and plasticity has been widely used in the cryogenic field. However, the appearance of coarse bainite in the heat affected zone (HAZ) of the fusion welded joint deteriorates the toughness and ductility. In this work, 4.5 mm thick SA516 Gr.70 steel was joined using shielded metal arc welding (SMAW) and friction stir welding (FSW), respectively, and the microstructure and mechanical properties of joints were investigated in detail. The Charpy energy in the HAZ in the FSW joint was 80 J/cm2, which was higher than that of the HAZ in the SMAW joint (60 J/cm2) and due to microstructure refinement. In addition, the total elongation (TE) of the SMAW joint was 17.5%, which was higher than that of the FSW joint (12.1%) and caused by a wider nugget zone with high hardness. The post-welding annealing was used to improve the toughness and ductility of the SMAW and FSW joints, and the microstructure and mechanical properties of the joints after annealing were analyzed. The toughness in the HAZ of the SMAW and FSW joints were 80 and 103 J/cm2, and the TE of the SMAW and FSW joints were 18.6% and 25.2%, respectively. Finally, the as-annealed FSW joints exhibited excellent toughness and ductility. The abovementioned excellent mechanical properties were primarily attributed to the appearance of tempering martensite, decrease in dislocation density, and fine grain. [ABSTRACT FROM AUTHOR]

Producing soundness weldments is the main goal to avoid catastrophic failures that occur in oil refineries, where the interaction of internal defects and residual stress with the working conditions leads to human and financial losses. AISI 1020- A106 carbon steel pipes that are used for oil products transmitted inside oil refineries have a 55 mm inner diameter with a 5 mm thickness and had been welded with shielded metal arc welding (SMAW) for the first samples group, while the second group was welded using gas tungsten arc welding (GTAW) process. For surface defects detection the liquid penetration method was used, while for internal defects radiography method was used, and for residual stresses X-ray diffraction was used. The results showed that the first group of samples contained different types of internal defects with compressive residual stresses, while the second group was nearly clear of internal defects with tensile residual stresses. [ABSTRACT FROM AUTHOR]