Shielded Metal Arc Research Articles

SELECTION OF TECHNOLOGICAL PARAMETERS OF MODES FOR MANUAL ARC WELDING OF SHUT-OFF VALVES MADE OF STEEL ALLOYED WITH 3–4 % NICKEL

Body of ball valves can be manufactured from A350-LF3 steel according to the US standard ASTM A350, alloyed with nickel up to 4 %. This steel has a tendency to harden in the heat affected zone during welding. The results of computer simulation showed that cooling rates during shielded metal arc welding exceed the recommended range. This can lead to the formation of hardening structures, the development of cold cracks and a decrease in the performance properties of welded joints of ball valves made of A350-LF3 steel.
 To prevent the formation of cold cracks, the preheating and concurrent heating temperatures were calculated. According to the results of computer simulation, it was found that pre-heating and concurrent heating provide the cooling rate of heat affected zone in the recommended range.
 The technology has been developed for welding ball valves made of A350-LF3 steel with mounting nozzles. This technology prevents the formation of cold cracks and provides a high level of strength and toughness of welded joints. The high level of mechanical properties of welded joints is confirmed by results of mechanical tests and metallographic studies.

The effects of heat input and electrode type on the mechanical properties of welded A309 stainless steel using a shielded metal arc welding

This study deals with an experimental study to evaluate the influence of heat and electrode type on the mechanical properties of welded A309 stainless steel using shielded metal arc welding (SMAW). Samples were prepared with a welding angle of 45 deg. Seventy-eight samples made of A309 stainless steel were used in the experiments, in which half of the pieces were welded using A309 electrodes and half with E7018 electrodes. The samples were subjected to a tensile test and Charpy test accordingly. Several parameters, such as welding current (I), heat input (H), the final length of the tensile specimen (Lf), elongation percentage (%E), yield strength (σy), and impact energy, were observed. The results show that the increase in current from 100 to 225 A causes the growth of heat input from 0.56 to 1.26 kJ/mm, impacting the decrease of the percentage elongation and yield strength, including the energy impact reduction. On the other hand, all mechanical properties tested have relatively low heat input at 0.56 kJ/mm and relatively high heat input at 0.7 kJ/mm

Effect of low frequency vibration-assisted shielded metal arc welding on the properties of mild steel

Vibration-assisted welding (VAW) has emerged to be a feasible alternative to thermal and post-weld vibration treatments for arc welds in order to minimize stress concentrations and distortions thereby improving mechanical characteristics. Limited research is available considering low frequency vibration. The main objective is to develop an experimental setup to analyze the properties of welded connections made with shielded metal arc welding (SMAW) using low-frequency mechanical vibrations. Mild steel (MS) plates with dimensions of 100 mm by 50 mm and thickness of 5 mm are considered in this study. Heat inputs of 80 Amps, 100 Amps and 120 Amps were taken into consideration as input current. Vibration was varied between 0 and 100 Hz at every 20 Hz interval to study the Hardness, Tensile Strength and Impact Strength of welded joints. Microstructure of welded MS plates has been analyzed using SEM analysis. Experimental results revealed improved mechanical properties due to the application of low-frequency vibrations that may tend to increase the welding speed thus reducing time and enabling stronger, durable and reliable welded joints. A fine grain structure is seen for Low-frequency vibration-assisted welded butt joints implying improved mechanical properties due to excitation of weld pool.

Numerical analysis of the residual stress state and distortions generated by autogenous welding and shielded metal arc welding (SMAW)

The present paper investigates, numerically, two welding techniques, by comparing the residual stresses introduced by each welding process. The first part of the paper proposes numerical modeling of the welding process by using APDL language (Ansys Parametric DesignLanguage) to integrate the Birth and Death Technique to take into account the effect of the filler metal deposition. The numerical model developed takes into account the difference between the mechanical behavior of the filler and base metal in order to increase the precision of the results. Also, the effect of temperature on the thermal and mechanical properties will be considered. The shielded metal arc welding and autogenous welding will be modeled and residual stresses will be calculated for each welding process. The results obtained show that the autogenous weld does not have a significant influence on the maximum residual stresses reached, however, the areas subjected to high levels of stress remain limited in the autogenous welds.

XRD Observation on the Weld Metal of Resurfaced Rail Steel

The current research studied two samples of rail steel grade 900A deposited with different electrodes, namely, electrodes A and B, using the Shielded Metal Arc Welding (SMAW) process. This research fi nds out the suitable hardness values of the various electrodes. The phase identifi cation and microstructural analysis of weld metal were conducted using X-ray diffraction (XRD) and an optical microscope, respectively. The micro-hardness profi les along the cross-section of the weldment were acquired using a micro-Vickers hardness tester, and a Brinell hardness tester measured the hardness values on the top surface of the weld metal. According to the results, the diffraction angles of the XRD patterns for all weld metal samples differed due to their distinct microstructures. The microstructure of the weld metal, in particular, produced the primary infl uence on the hardness

Exploring the Impact of Cooling Rate on Microstructural Features, Mechanical Properties, and Corrosion Resistance of a Novel Nb-Stabilized Super Duplex Stainless Steel in Shielded Metal Arc Welding

The corrosion and mechanical response produced by quenching in the welded joint of a new Nb-doped stainless steel designed by the CALPHAD method and produced by open-atmosphere casting with recycled materials were investigated to contribute to the circular economy and to establish disruptive manufacturing criteria based on metallurgical principles. The steel was initially subjected to solubilization heat treatment and partial solubilization treatment at 1090 °C to obtain an appropriate α/γ balance and carbide solubilization. It was then welded by the SMAW process, quenched, and tempered at three different cooling rates. As a result, a good fit between the phases predicted by the CALPHAD method and those observed by X-ray diffraction and scanning electron microscopy were obtained, with minor differences attributable to the precipitation and diffusion kinetics required for dissolution or nucleation and growth of the phases in the system. The forced air quenching mechanism was identified as providing an α/γ phase equilibrium equivalent to 62/38 as the most effective quenching method for achieving the optimum mechanical and corrosion response, even with the post-weld σ phase and showing superior results to those of the base metal. The outstanding mechanical and corrosion responses resulted from a proper balance of the primary phases in the duplex steel with a precipitation-strengthening mechanism. The damage tolerance obtained by forced air quenching was superior to that obtained by water and air quenching, with a PSE of 24.71 GPa% post-welding.

Estimation of Particle Emission Rates and Calculation of Human Dose from Arc Welding and Cutting of Stainless Steel in a Simulated Confined Workspace

The objective of this study was to estimate the particle emission rates, human dose and retention from two arc welding processes and cutting of stainless steel. The two arc welding processes were Shielded Metal Arc Welding (SMAW) and Tungsten Inert Gas (TIG). In a simulated confined workspace of experimental chamber under controlled conditions, four different scenarios were considered, including the use of filtering face piece respirator (FFR), leaving or staying in the workspace after the emission. Deposited and retained dose in the respiratory tract was assessed for the different regions of the human respiratory tract using a dosimetry model (ExDoM2). The three investigated processes generated high particle number concentrations ranging from 2.4 to 3.6 × 106 particles/cm3 and were the highest during TIG. Among all three processes, PM10 concentrations from cutting reached the highest levels [11 and 22 (× 103) μg/m3], while SMAW had the highest contribution of fine particles [~ 4.1 (× 103) μg/m3], consisting mostly of PM1–2.5. The examination of different scenarios revealed that there is only a slight difference in respect to deposited dose while staying in the workspace for the entire investigated time period (4 h) with or without use of Filtering Facepiece Respirator (FFR). It would be more beneficial in respect to deposited dose if the exposed subject was not wearing a FFR during the emission process and would leave the polluted workspace immediately after the emission period. In the first two scenarios (staying 4 h in the polluted workspace with and without FFR), both welding processes had higher cumulative deposited (~ 23%) and retained dose (~ 20%) in thoracic region compared to cutting (~ 9% and ~ 7%). These results demonstrate that even a short emission period can cause a considerable increase in concentrations of harmful respirable particles, thus increasing the human dose. The approach applied in this study could be used for the determination of personal exposure and dose to particles of known composition particularly in confined workspaces.

Effects of graphene oxide addition in properties of shielded metal arc weld joints

Effects of graphene oxide addition in properties of shielded metal arc weld joints

Analysis of the Effects of Polarity Variations, Electrode Types, and Cooling Media on the Tensile Strength of ASTM A36 Steel Welded Joints

This research investigates the pivotal role of welding in manufacturing and construction, specifically in the context of material joining for ASTM A36 steel. The study aims to determine the impact of polarity, electrode type, and coolant on the maximum tensile strength of welds. A total of 54 specimens were welded using Shielded Metal Arc Welding (SMAW) with DCEN and DCEP polarities, employing electrode variations of E6013, E7016, and E7018, along with different coolants—Air, Oil, and Saltwater. The results reveal that E7018 welding at a speed of 100 mm/s exhibited the highest tensile strength of 529 MPa, with an average maximum load of 37.35 kN. Conversely, the lowest tensile strength was observed in E6013 welding at 100 mm/s, recording 339 MPa with an average maximum load of 25.84 kN. Additionally, E7018 welding at a speed of 100 mm/60 s showed the highest elasticity of 22.08% with a maximum load of 37.55 kN. These findings contribute valuable insights for optimizing welding processes, thereby enhancing the mechanical integrity of ASTM A36 steel in various industrial applications.
 Highlights:
 
 Significance of Polarity: Investigating the impact of DCEN and DCEP polarities on welded material strength. 
 Electrode Influence: Understanding how E6013, E7016, and E7018 electrodes affect the mechanical properties of welds.
 Coolant Consideration: Analyzing the role of Air, Oil, and Saltwater as coolants in optimizing welding outcomes.
 
 Keywords: Welding, ASTM A36 steel, Polarity, Electrode, Coolant

Influence of Heat Input on the Weldability of ASTM A131 DH36 Fillet Joints Welded by SMAW Underwater Wet Welding

Naval vessels face multiple risks that can damage their hulls during navigation, leading to on-site repairs through the shield metal arc welding (SMAW) process and underwater wet welding (UWW). This paper presents a weldability study to identify the optimal heat input parameters to improve ASTM A131 DH36 welded joints quality, development, and sustainability. This study analyzes the influence of heat input on the microstructure and mechanical properties of underwater wet welding fillet joints welded with shield metal arc welding at 4 m water depth in a real-life environment located at the bay of Cartagena (Colombia). The methodology involves nondestructive and destructive tests, including visual inspection, fillet weld break, scanning electron microscopy (SEM), X-ray diffraction (XRD), Vickers hardness, and shear strength tests. The welds microstructure is composed of ferrite, pearlite, retained austenite, bainite, and martensite; the hardness values range from 170 HV1 to 443 HV1, and the shear strength values range from 339 MPa to 504 MPa. This indicates that high thermal inputs improve the weld quality produced by the underwater wet welding technique and can comply with the technical acceptance criteria of AWS D3.6, making them more sustainable, with less welding resources wastage and less impact on marine ecosystems.

Selection of Electrode Material for Inconel 617/P92 Steel SMAW Dissimilar Welds

Abstract The present work aimed to investigate the microstructure and mechanical properties of the dissimilar shielded metal arc welded (SMAW) joint of Alloy 617 and P92 steel for advanced ultrasupercritical boilers. The SMAW joint was produced using three different types of electrodes, namely, ENiCrFe-3, ENiCrMo-3, and ENiCrCoMo-1. During microstructural observation of the welded joints, no possible cracking was detected in the weldments. The dissimilar metal welds (DMWs) obtained using the ENiCrCoMo-1 electrode showed the maximum tensile strength, while the minimum was obtained for the ENiCrFe-3 electrode. Among all the electrodes, the ENiCrFe-3 electrode exhibited the maximum impact toughness, while the minimum was obtained for ENiCrCoMo-1 electrodes. Based on microstructure and mechanical characterization, the ENiCrFe-3 electrode was selected as the best one among all to produce the DMW of Alloy 617 and P92 steel.

Structural Integrity Assessment of Inconel 617/P92 Steel Dissimilar Welds Produced Using the Shielded Metal Arc Welding Process

Structural Integrity Assessment of Inconel 617/P92 Steel Dissimilar Welds Produced Using the Shielded Metal Arc Welding Process

Self-Directed Learning Strategies in Studying Modularized Oral Communication in Context

COVID-19 pandemic required Grade 11 Shielded Metal Arc Welding (SMAW) students to study modularized Oral Communication in Context. Focusing on their specialization, while comprehending this subject independently, brought them learning difficulties. Delving into their experiences, this study sought to examine their self-directed learning strategies through qualitative-phenomenological method. With purposive sampling, the researchers selected self-directed participants as qualified ones for one-shot in-depth interview. Employing Colaizzi’s technique, the researchers analyzed and clustered responses into themes. Results revealed that students experienced subject learning difficulties, home learning environment distractions, concentration difficulties, independent learning adaptation, beneficial self-directed learning strategies, teacher’s valuable role, and optimism for the sake of educational benefits. Their self-directed learning strategies encompassed self-preparatory strategies, learning environment-preparatory strategies, technological learning strategies, non-technological learning strategies, information overloadmanagement strategies, time-management, and persistence-regulatory strategies. These inspired the researchers to craft self-directed learning strategy toolbox as students’ reference in overcoming the challenges. Further, this paper encouraged learning resource writers to ensure the contextualization of self-learning modules and teachers on the modification or delimitation of modular tasks. Finally, future researchers might also pursue a study on educational key players’ perspectives on these findings and evaluation of the toolbox.

Analysis of Effect of Temperature Variation Preheat on SMAW Welding of Microstructures, and ST60 and SS400 Steel Hardness

Welding is a metal joining process by melting some base and filler metals. SMAW welding (Shielded Metal Arc Welding) is one of the industry's most widely used welding methods. SMAW welding requires preheating (preheating) to reduce residual stress, distortion, and cold cracking in the weld metal. Preheat also can affect the microstructure and hardness of the weld metal. This study aims to analyze variations preheating on SS400 and ST60 steel against micro tests by SMAW welding, namely electric arc welding with covered electrodes. Temperature variation preheating used in SS400 steel was 140°C, 170°C, 300°C and 400°C in ST 60 steel. The results showed that the higher the temperature preheat, the larger the grain size of the microstructure in the parent metal region, the heat-affected area, and the weld metal area. The higher temperature preheat also led to a decrease in violence in the three areas. ST60 steel has a larger microstructure grain size and lower hardness than SS400 steel at all temperature variations preheat.

Microstructure characteristics in weld zone of the novel thick 08Cr9W3Co3VNbCuBN heat-resistant steel welded joint by fusion welding

ABSTRACTOne of the primary candidate materials used in 650°C ultra-supercritical (USC) thermal power plant units is a novel thick grade of heat-resistant steel, 08Cr9W3Co3VNbCuBN (G115), for which China has complete intellectual property rights. In this study, G115 steel with a 115 mm thick wall was successfully welded using gas tungsten arc welding (GTAW) + shielded metal arc welding (SWAM), which was a significant step toward achieving its application in large-diameter boiler tubes. The influence of the welding process on the microstructure and mechanical properties of the G115 welded joint after post-weld heat treatment (PWHT) at 770°C for 11 h was investigated. The findings demonstrate that the weld zone (WZ) after PWHT was composed of martensite and ferrite, and M23C6 was the precipitate. The average hardness of WZ was 273.1 HV, and the average impact toughness was above 39J, which was sufficient for actual production applications. It offered the necessary theoretical foundation for the practical development of thick-walled G115 heat-resistant alloy steel during welding.

RETRACTED ARTICLE: Optimization of process variables for shielded metal arc welding dissimilar mild steel and medium carbon steel joints

We, the Editors and Publisher of the Journal of Adhesion Science and Technology , have retracted the following article: Vijayakumar, S., Arunkumar, A., Pradeep, A., Satishkumar, P., Singh, B., Rama Raju, K. S., & Sharma, V. K. (2024). Optimization of process variables for shielded metal arc welding dissimilar mild steel and medium carbon steel joints. Journal of Adhesion Science and Technology, 38(2), 185–202. https://doi.org/10.1080/01694243.2023.2227461 Since publication, a third party has raised concerns about the integrity of the data presented in the article and potential authorship concerns. When approached for an explanation, the authors have been unable to provide their original data to verify its authenticity. In addition, the authors have not fully responded to our questions regarding the process of the research conducted. As part of the investigation, we have been made aware of additional concerns regarding the inclusion of some authors on the author list, but the journal has been unable to verify these concerns, so the original author list is maintained. We have been informed in our decision-making by editorial policies and the COPE guidelines. The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as ‘Retracted’.

Selection of Joint Preparation Procedure based on Cost-effectiveness and Defects analysis of Double-V SMAW Joint

Double sided shielded metal arc welded joint has wide applications in fabrication sector for production of critical joints but the root pass in those joint leads to many defects, mainly due to the sudden cooling because the adjacent base material is at room temperature in the start of welding and compromises the quality of the weldments. In the fabrication industry, root pass removal is a routine practice for producing quality joints using grinding and air carbon arc gouging. In this research, comparative study of cost-effectiveness and defects analysis of the above root pass removal procedures have applied to the double-v mild steel shielded metal arc welded joint for the selection of better procedure. For cost calculation of joints, labor cost (LC), energy cost (EC), material cost (MC) and overhead cost taken into account and defects examined by the visual inspection, liquid penetrant test, radiographic test and optical microscope. The results showed overall 4.7% lower cost and enhanced quality in terms of macro/micro-defects for ground joint. The major contribution to the lower cost of ground joint has given by the consumables and energy but in defects analysis, only width difference in both sides’ reinforcement i.e., front and back have observed for gouged joint and relatively more numbers of micro-defects.

Mechanical Properties Of Welding API 5l X-65 Cladded UNS N08825 Material Due To The Effect of Welding Repair

Abstract This study evaluate the mechanical characteristics and microstructure of API 5L X-65-clad UNS N08825 during repair welding. Gas tungsten arc welding (GTAW) and shielded metal arc welding were used in combination to carry out the welding and the repair welding (SMAW). Filler metals ER NiCrMo3 and E NiCrMo3 were used throughout the GTAW and SMAW welding processes. The first specimen served as the primary focus, after which the weld areas of the remaining four specimens were ground, re-beveled, and then re-welded using the same parameters. It performed tensile testing, bending tests, Impact Charpy tests, macro photography tests, and Vickers hardness tests. Repairs weld carried out, the heat-affected zone's hardness in the capping region increased. The findings of the tensile test demonstrate that the tensile strength is not considerably impacted by the welding repair at any particular welding repair location. The biggest decline in the number is caused by the welding repair at PTR 2, which is 0.83 percent. The heat affected area (FL) value decreased by 10.44 percent according to the charpy impact test results. The PTR 1 and PTR 2 areas in the weld metal area had the lowest charpy impact test results, respectively, of 88 J and 258 J.

Nanosilica treatment enables moisture-resistant hydrophobic arc welding covered electrodes

Controlling the moisture content of the electrode-covering is crucial in the production of defect-free, high-quality welds during shielded metal arc welding of steels. The welding industry has long faced the challenge of the high susceptibility of basic electrodes (e.g., E7018) to moisture absorption. In this paper, we demonstrate that applying a nanosilica coating to the surface of the E7018 electrode-covering using a dip-coating technique can effectively reduce the moisture absorption capability of the electrode-covering. The moisture measurement results before and after exposure to a moist environment of 80% humidity and a temperature of 27 °C for 9 h indicate that the moisture absorption values of conventional and nano-treated E7018 electrodes during exposure are 0.67 wt% and 0.03 wt%, respectively. While reducing the size of the pores on the surface of the electrode-covering can to some extent enhance the resistance to moisture absorption, it has been identified that turning the wetting behavior of the electrode-covering surface from hydrophilic to hydrophobic by the nanosilica coating is the most effective mechanism that contributes to the enhanced moisture absorption resistance of the nanosilica-treated electrode-covering. The results indicate that this approach does not have any deleterious effects on the chemical analysis and tensile properties of the weld metal. This simple modification to the electrode-covering can be generally applied to a wide range of electrode-covering types to produce hydrophobic, moisture-resistant electrodes.

Analysis and Optimization of Shielded Metal Arc Welding Parameters on Mechanical Properties of Dissimilar Materials

Shielded metal arc welding is the most efficient and economical process through which it can easily weld. Residual stress is prompt in the welding process. In, some of cases, there is entrapment and deformation that can endanger the coherence of welding properties. So, the mechanical properties of welded joints can be changed accordingly to the heat-affected zone. In this study, the joint between two dissimilar AISI304 steel and Mild steel having a thickness of 5mm which is welded through a shielded metal arc welding (SMAW) in the V-groove shaped has been produced. In this research, we examines the mechanical properties of the material and their experimental and numerical analysis can also be measured through the Ultimate Tensile test, which introduces the entrapment and distortion of the finite element. It mainly focusses on final outcomes of the accuracy and strength of the material has been investigated.