Shielded Metal Arc Welding Process Research Articles

Texture and surface morphology influence of A106 carbon steel pipe on mechanical properties and corrosion resistance after welding process

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.

Microstructure-Linked Mechanical Properties of P91-Incoloy 800HT Dissimilar Metal Welds

Dissimilar metal welds (DMWs) between P91 steel and Incoloy 800HT® using shielded metal arc welding (SMAW) with ENiCrCoMo-1 filler electrode were characterized in detail. The impact of multiple weld passes on microstructure in the heat-affected zone (HAZ) and weld fusion zone (WFZ) was thoroughly investigated. Postweld heat treatment (PWHT) impacts on mechanical characteristics and microstructure were also observed. The DMW was observed with heavy C, Cr, and Mo microsegregation in the WFZ, which deteriorated mechanical strength. The microstructural changes directly affected the mechanical behavior of the DMW. The ultimate tensile strength of the weld fusion zone was low at 576 MPa compared to the base metals’ strength. The tensile specimens failed in the IN 800HT base metal and WFZ. The WFZ had significant microsegregation near the solidified grain boundaries (SGBs). The metallurgical heterogeneity in the WFZ caused the formation of localized stress zones, which directly affected the mechanical behavior of the WFZ. The carbide particles influenced the microhardness in the WFZ and P91 HAZ regions. The PWHT successfully homogenized the microhardness in the WFZ and P91 HAZ regions. The impact toughness decreased to 64 J from 82 J after PWHT due to precipitation at SGBs and its coarsening. The SMAW process involves multiple thermal cycles during welding. The deposition of filler metal in multiple welding passes created uncontrolled variations in the solidification behavior of the WFZ. Microsegregation had a detrimental impact on the microstructure and mechanical properties of the P91 and IN 800HT dissimilar metal welds.

Effect of welding parameters on microstructure and mechanical properties of dissimilar AISI 304/ductile cast iron fusion welded joints

Problems associated with dissimilar fusion welding are mainly originated from the differences in melting points, coefficients of thermal conductivity and thermal expansion, …etc., and carbon content when welding dissimilar ferrous materials. In this study, the problems associated with dissimilar fusion welding of stainless steel AISI304 with ductile cast iron DCI grade A536 were investigated. Using shielded metal arc welding (SMAW) process, various welding parameters were studied to investigate the successful/accepted dissimilar welded joint(s). Welding electrodes and welding techniques were the main studied parameters. Microstructural and mechanical investigations were carried out for welded joints under different welding parameters. Tensile, impact and hardness tests coupled with optical and scanning electron microscopic examinations with EDX analysis were made for metallurgical and mechanical evaluations of welded joints. This extensive study could solve the problem of dissimilar welding between ductile cast iron and 304 stainless steel. The main results showed that joints welded by ENiCrFe-3 electrode in root pass and ENiFe-CI in filling passes were the successful dissimilar welded joints with 422 MPa tensile strength which represents 104% of annealed DCI base metal and without any changes in toughness properties, where toughness at HAZ of DCI was 18 J. High Ni content in weld metal increased the strength, ductility and reduced the weld metal dilution.

Comparative study of electrogas and shielded metal arc welding processes on steel A537 welded joints

In this research, the electro-gas welding process was compared with a shielded metal arc welding process for welding steel A573 from a mechanical properties point of view. Visual and radiographic inspections confirmed the soundness of weldments produced by electro-gas welding and shielded metal arc welding techniques. Various assessments were performed, including hardness, tensile strength, V-notch impact toughness, macrostructure, microstructure, and electrochemical tests. The mechanical properties of the two welding processes were closely matched, with an average tensile strength of 590 MPa for electro-gas welding and 585 MPa for shielded metal arc welding. Furthermore, the influence of welding variables, such as groove design and heat input, on the welded joints’ quality, mechanical properties, and electrochemical behavior was thoroughly examined. Dilution estimates, particularly for the electro-gas welding process, were around 35%, and a significant similarity was observed between the chemical composition determined through dilution calculations and that obtained from chemical analysis using an arc spark emission spectrometer. Notably, the electro-gas welding process demonstrated exceptional productivity, surpassing the shielded metal arc welding process by more than elevenfold. The optimum welding parameters for the electro-gas welding process were identified to achieve superior mechanical properties, low corrosion rates, and reduced consumption of the welding electrodes. This included adopting a single V type and groove angle of 30° instead of 60°, resulting in a 23% reduction in economic costs. Selecting an appropriate heat input within the range of 12 to 14 kJ/mm further contributed to enhancing overall welding efficiency.

Experimental Investigation of Optimal Welding Parameters and Mechanical Properties of Shielded Metal Arc Welded Mild Steel Plates

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.

PENGARUH TITANIUM DALAM LAPISAN LAS TERHADAP STRUKTUR MAKRO-MIKRO, KEKERASAN, DAN LAJU KOROSI

Low carbon steel cannot be hardened because of its low carbon content. Therefore, a hardfacing process is carried out to increase hardness. Apart from increasing hardness, the benefits of hardfacing can increase wear and corrosion resistance. The hardfacing process using the shielded metal arc welding (SMAW) process generally uses commercial electrodes. Therefore, it is necessary to add other elements such as titanium (Ti) to the weld layer to further increase its hardness. This research aims to study the influences of Titanium (Ti) addition in welding layers that were welded using HV 600 to micro and macrostructure, hardness, and corrosion rate. The hardfacing was conducted using the SMAW process with the various addition of Ti (0.115, 0.223, and 0.334 g) and cooled at room temperature. Macrostructure and microstructure were investigated using digital cameras and an optical microscope. Hardness and corrosion rate were investigated using the Vickers hardness test and weigh loss method. Based on macrostructure investigation, there is a perfect fusion between base metal and weld metal. The microstructure formed is a austenite, martensite and carbide phase. The lowest corrosion rate of 17.54 mpy was seen in the Ti1 sample. The lowest Ti addition would resulting higher hardness at 761.06 VHN.

Combined Gas Tungsten Arc Welding and Shielded Metal Arc Welding Processes for Joining Tube to Tubesheet in Shell and Tube Heat Exchangers

Abstract Flawless tube and tubesheet joints are necessary for shell and tube heat exchanger with high leakproof ability and durability. The consequence of mixing of transfer fluids due to the defective welded or expanded tube-to-tubesheet joint results in complete malfunctioning of the heat exchange process. In this case, there is a high demand for quality assessment of the fabricated tube-to-tubesheet joints (TTS) based on the international standards. Additionally, the literature on assessing the mechanical and metallurgical characteristics of tube-to-tubesheet joints using any one welding technique is available; however, articles dealing with the use of multiple welding techniques are scanty. In the current work, the quality assessment of strength welded and light expanded (3%) tube-to-tubesheet joints followed by light expansion was performed whereas for welding, combined gas tungsten arc welding (GTAW) and shielded metal arc welding (SMAW) as root pass and cap pass were adopted in the fabrication stage. Quality and sound tube-to-tubesheet joints were produced using welding and tube expansion process. Linear and circular indications representing the cracks were absent on the developer in the liquid penetration test. The minimum leak path (MLP) was greater than the two-third of tube wall thickness. The results strongly qualify the use of combined gas tungsten inert gas and shielded metal arc welding process for manufacturing of tube-to-tubesheet joints. The methodology and results in the current article are beneficial for researchers and industrialists working close to shell and tube heat exchangers and boilers.

Investigations on Transient Temperature Distribution and Distortion in Shielded Metal Arc Welding of SA 516 Gr. 70 Steel

Efforts are made in this article to investigate the thermal and mechanical phenomena by presenting a coupled thermal and structural analysis of SA516 Grade-70 steel. This material has wide applicability in the fabrication of pressure vessels, boilers, etc., due to its excellent weldability and formability. An actual ongoing problem from a reputed industry, related to distortion during the shielded metal arc welding process, is considered and experiments are carried out on the chosen steel. Results are evaluated employing a two- step methodology, involving simulation. The first step encompasses thermal analysis, providing insights into transient temperature distribution, while the subsequent mechanical analysis offers data on residual stresses and distortion. In the case of heat input, a volumetric heat source with double ellipsoidal heat distribution is used whereas a plasticity material model with rate-independent bilinear kinematic hardening is adopted for the structural analysis. Additionally, temperature-dependent material properties are factored into both scenarios. The data derived from numerical analysis align closely with experimental findings, presenting valuable insights for fabricating industries.

Experimental and Numerical Investigation on Ballistic Performance of Ultra High Hard Armour Steel Joints Welded Using Shielded Metal Arc Welding Process and Austenitic Stainless Steel Electrode

Experimental and Numerical Investigation on Ballistic Performance of Ultra High Hard Armour Steel Joints Welded Using Shielded Metal Arc Welding Process and Austenitic Stainless Steel Electrode

EVALUATION OF WELDED JOINT (SMAW) AFTER POST WELD HEAT TREATMENT (PWHT)

Joining of two materials having similar physical, chemical, and thermal properties and to make the joint tough and stiff, special attention and investigation are required. In this research, the welding joint between two mild steel (MS) of IS 2062 grade E, was accomplished by using shielded metal arc welding (SMAW). To investigate the effect of electrode in the welding joint, MS electrode was exercised. For post-weld heat treatment (PWHT), temperature of 700 °C were investigated over the welded specimen. To explore the optimum welding process and PWHT process for this joint, both tensile and bending tests were carried out. Destructive tests have suggested that PWHT at 700 °C is better for the SMAW process with MS electrode. As the smallest hardness values were observed in the heat-affected zone (HAZ) which makes the sample susceptible to failure. The hardness values have decreased after PWHT which justified the achievement of higher ductility after heat treatment.

Microstructure, mechanical properties and sensitization of ultra-low nickel Cr–Mn austenitic stainless steels

The present study deals with the effect of shielded metal arc welding (SMAW) and gas metal arc welding (GMAW) processes with different welding speeds on microstructural and mechanical properties including intergranular corrosion susceptibility of ultra-low nickel chrome-manganese austenitic stainless steel (ASS). The microstructural analysis was performed by an optical microscope. The Fisher Ferritscope was used for determining ferrite content in the weldment. The microstructural analysis shows that the size of dendrites of δ ferrite and the width of heat affected zone (HAZ) decreases when welding speed increases. It was found more δ-ferrite in SMAW weld compared to GMAW weld. It was also found that when welding speed increases, tensile strength, impact strength and hardness values decrease for both welding processes. From the U-bending test, it was found that the welded joints are strong enough to withstand bend at 1800 without any cracks for both welding processes. It was also found that Cr-Mn ASS weld becomes susceptible to intergranular corrosion on welding. For both welding processes, the degree of sensitization value decreases with an increase in welding speed for both the welding processes as evaluated by the double loop electrochemical potentiodynamic reactivation (DLEPR) test. Also, the weld joint made using the GMAW process is more susceptible to intergranular corrosion than that made using the SMAW process.

Experimental and numerical investigation on optimization of welding parameters and prediction of temperature distribution during shielded metal arc welding of ultra high hard armor steel joints

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.

Operational performance and metal droplet formation in pulsed-shielded metal arc underwater welding

Underwater Shielded Metal Arc Welding (SMAW) is highly affected by the welding depth. The arc and molten metal in contact with the surrounding environment cause operational and metallurgical challenges regarding arc stability, metal transfer, gas formation, high-cooling rates, and diffusible hydrogen uptake. The hydrostatic pressure causes losses in consumable fusion efficiency, constricts the arc, increases the number of short-circuit events, and consequently decreases the welded joint’s process quality. In the present study, the novel approach of pulsed welding current is applied to wet shielded metal arc welding and is operational characteristics are evaluated in detail. Automated welding using an arc-voltage control system was used to obtain reproducible results. For the pulse conditions, two values of pulse current combinations, taking 140 A as the mean value, were set (ΔI of 40 A and 80 A). The same pulse and base duration were chosen, giving pulsing frequencies of 2.5 Hz and 25 Hz. The voltage and current signals were acquired and the short-circuit numbers and melting rates were calculated by processing the data stability factors. As a result, it was possible to weld with lower average welding currents through pulsed-current technology. This new approach can improve the stability of the wet SMAW process and contribute to obtaining better-quality welds without any changes for the underwater welder.

STUDY OF GEOMETRIC UNSHARPNESS PHENOMENON IN WELDED PLATES USING INDUSTRIAL RADIOGRAPHY METHOD

The purpose of this document is to elucidate the methodology employed in analyzing the impact of unsharpness resulting from an X-ray generator on the assessment of steel welded joints. The presence of unsharpness significantly affects the accuracy of welded joint inspections conducted through industrial radiographic techniques, distorting actual measurements of potential discontinuities within the weld. To address this issue, a series of welded joint testing specimens were fabricated using a Shielded Metal Arc Welding (SMAW) process. Each specimen was intentionally designed to contain simulated discontinuities whose dimensions adhered to the acceptance or rejection criteria outlined in the API 1104 standard. Subsequently, radiographic testing was conducted on each specimen, and the dimensions of the simulated discontinuities captured on the radiographic films were measured using the "ISee!" software, as recommended by the ASTM E1165 standard. Upon comparison of the actual and theoretical measurements, it was observed that the maximum unsharpness along the X-axis was recorded in specimens featuring elongated slag inclusions (ESI), with a value of 0.1948 mm. Conversely, the maximum unsharpness along the Y-axis was attributed to individual porosities (P), with a recorded value of 0.1041 mm.

Creep behaviour of dissimilar weld joint between buttered Grade 91 steel and Alloy 800

Creep rupture behaviour of dissimilar weld joint (DWJ) between buttered Grade 91 steel (G91) and Alloy-800 fabricated by Shielded Metal Arc Welding (SMAW) process is investigated at 873 K over a stress range of 90–160 MPa. DWJ exhibited lower creep rupture strength than the G91 steel and the failure location of the DWJ shifted with applied stress. At high stresses (≥140 MPa) fracture occurred in the over-tempered region of base metal, whereas it shifted to HAZ at lower stresses. In contrast to interface failures being considered the life-limiting factor in DWJs, the ruptured specimens in the present study revealed a clear interface (between the buttering layer and G91) free from deleterious coarse carbides and insignificant cavitation even after creep exposure of ≈ 5800 h. It’s important to highlight that the buttered G91 DWJ exhibited higher rupture life and weld strength reduction factor compared to joints fabricated without buttering by the SMAW process.

A Comparative Assessment of Chromium–Boron Hardfacing Using SMAW and FCAW Techniques

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.

Prediction of Residual Stresses in 316 Stainless Steel Pipes Welded Joint

Due to the extremely complicated thermal cycle for the welding process, the fusion zone and heat-affected zone (HAZ) produce irreversible elastic-plastic deformation and residual stresses. The differential heating of the pipes caused by the weld heat source causes residual stress as a result of the welding process. However, the strength and lifetime of the component are also decreased as a result of residual stresses in and around the weld zone. The objective of this research is to analyze the residual stresses created during the welding process and select the best welding parameters that give the lowest residual stresses in 316SS pipes with 50 mm diameter and 4 mm thickness that were manually welded by used (316) welding wire and using shielded metal arc welding (SMAW) in a single-pass butt joint with the various values for each of current (58, 68, 78, 88) amperes and voltage (22, 23, 24, 25, 26) volts. The shielded metal arc welding process involves heating, melting, and solidifying the parent metals and filler material in a localized fusion zone by a transient heat source to create a junction between the parent metals. The welding process free from preheating and heat treatment will be obtained. ANSYS Finite Element methods are used to calculate the welding residual stress distribution. The mechanical and thermal models were used to carry out the theoretical analysis. In general, the numerical study found that the residual stress distribution at the weld zone’s center is continuous, rising, and has a value of about (1738 MPa). Additionally, the residual stress at the boundary between the heat-affected zone and the weld zone climbs to a maximum value of around (3799.6 MPa). On the other hand, the magnitude of the residual stress in the heat-affected zone of the weld reduces significantly and achieves a minimum value at a position of (20 mm) with a value near zero.

Biomonitoring of exposure to multiple metal components in urine, hair and nails of apprentice welders performing shielded metal arc welding (SMAW)

Welding fumes are associated with various diseases. Increased air levels of metals were reported during welding. However, few multielement biomonitoring studies were conducted to assess the actual dose of metal components absorbed in apprentice welders in a learning environment. This research aimed to establish the nature and level of exposure to welding fumes and their metallic components in apprentice welders performing ‘Shielded Metal Arc Welding’ (SMAW), based on multi-element and multi-matrix analyses. A total of 86 apprentice welders were recruited in three different schools in Montreal, Québec, Canada. Twenty-one elements were measured in urine, hair, fingernail, and toenail samples collected at the beginning of the program and at the end of SMAW practical training. Concentrations of welding fumes and 12 metals were also determined in personal respirable air samples collected over a typical workday in a subgroup of 19 apprentices. Levels of manganese (Mn), iron (Fe) and nickel (Ni) in urine and Mn in hair were higher in samples taken at the end of the SMAW module compared to the beginning of training, while there was no significant difference for the other elements or for nail concentrations. Geometric mean concentrations [5th-95th percentiles] reached 0.31 [0.032–2.84], 9.4 [3.1–51] and 0.87 [0.35–3.1] μg/g creat. in post-shift urine, respectively, for Mn, Fe and Ni, and 0.37 [0.46–6.4] μg Mn/g hair at the end of SWAW. Median concentrations [5th-95th percentiles] were 29 [4.6–1200], 120 [27–3100] and 0.31 [<LOQ-0.92] μg/m3 for Mn, Fe and Ni, respectively. The work showed that even short-term welding fume exposure in controlled environments, as observed in apprentice welders after SMAW process, increases internal exposure to metals. It also confirmed the interest of measurements in multiple matrices to assess internal metal exposure. The follow-up of apprentices during standard curriculum will allow to assess more long-term internal exposure due to other welding processes.

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

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.