Shielding Gas Research Articles

Residual Stress and Distortion Analysis for TMCP Steel Grade EH36 Butt Welding Parts in GTAW-SMAW Hybrid Welding Process using Finite Element Method

The present work evaluates residual stress and distortion in Thermo-Mechanical Control Process (TMCP) grade EH-36 steel plates subjected to hybrid Gas Tungsten Arc Welding (GTAW) and Shielded Metal Arc Welding (SMAW) processes Specimens measuring 650 × 170 mm with a thickness of 12 mm were utilized. Finite Element Method (FEM) analysis was employed to model residual stress and distortion, a critical step in optimizing the manufacturing process of mechanical structures and parts in shipbuilding. The FE model was developed using ANSYS software incorporating a heat source model with a user-defined subroutine to represent an ellipsoidal moving weld torch with front and rear power density distribution. Heat losses due to radiation and convection were accounted for, while mechanical boundary conditions were applied to restrict rotation and displacement but allow material deformation. Thermal analysis demonstrated close agreement between experimental thermocouple data and numerical simulations, with a temperature deviation of only 5%. Residual stress analysis using X-Ray Diffraction (XRD) revealed that ultrasonic stress relief reduced the maximum residual stress from an average of 193.4 MPa to 39.1 MPa Distortion analysis showed that the maximum FEM deformation was 0.2873 mm, with a 12% deviation from coordinate measuring machine (CMM) results, while the minimum FEM deformation was 0.031922 mm, differing by 3%. The larger deviation occurred in areas with peak distortion, attributed to variations in mechanical restraint positioning, which significantly influence material deformation during cooling.

Investigation of the plume mechanism in high-power laser-arc hybrid welding using spatio-temporal resolved spectroscopy

The laser arc hybrid welding process plays an important role in modern industry. Research on the morphology and spectral characteristics of the plume during this process is of great significance for a deeper understanding and improvement of the technology and process. In this paper, we conducted a study of the high-power laser welding, arc welding, and laser-tungsten inert gas (TIG) welding hybrid welding processes. We improved the experimental parameters based on the original imaging and spectral measurement methods, combined with the imaging spectrometer, and designed a spectral measurement method based on high time and space resolution. This was the first study to investigate the high-dynamic plume morphology and spatially resolved spectral characteristics of the welding process on a nanosecond time scale. The temperature and electron density of the plume were found to be significantly increased due to the coupling effect of different heat sources. Furthermore, the spatial variation of the plume temperature and electron density was demonstrated in the experiment, providing a new perspective for a more accurate understanding of the relevant spectral characteristics.

Enhanced Forging Die Lifespan with Novel Alloy Composition Overlay Coating Using Metal Inert Gas Welding

Hot work die steel possesses better elevated temperature properties that are desired for hot working application. In the present work, the life of forging die steel (DIN 1.2714) was extended by surface overlay coating using metal inert gas welding, which decreases die wear. This study compares two distinct iron-based overlay coating compositions applied to forging dies and samples, followed by tempering and exposure to varying cooling rates. The microstructure of the coated samples was analyzed through optical and scanning electron microscopy. These different coatings, along with the varied cooling rates, were assessed to identify conditions that reduce defects and improve the longevity of the forging die. The forging die’s lifespan was observed to increase by 44%, which can be attributed to the selection of suitable alloying elements for the overlay coating and the optimization of the cooling rate.

Investigation of the Microstructures and Fracture Failure Mechanisms of Metal Active Gas Welded Joints of Dissimilar 304 Stainless Steels and Q235B/Q345 Low-Carbon Steels

Investigation of the Microstructures and Fracture Failure Mechanisms of Metal Active Gas Welded Joints of Dissimilar 304 Stainless Steels and Q235B/Q345 Low-Carbon Steels

Welding of Solid-State-Recycled Aluminum Alloy: Comparative Analysis of the Mechanical and Microstructural Properties

The main aim of this research is to investigate the possibilities and challenges involved in the electric arc welding of solid-state-recycled EN AW 6082 aluminum alloy. Lately, solid-state recycling has gained increased attention as a more sustainable and efficient aluminum recycling method, whereby only about 30% of the energy of conventional recycling is used. This method is based on the deformation of small-sized metal waste into solid recycled specimens without a remelting step. For the welding of solid-state-recycled specimens, both metal inert gas welding and tungsten inert gas welding methods are used. To evaluate the weldability of solid-state-recycled material, welded specimens are compared with welded, commercially produced EN AW 6082 aluminum alloy sheets. The welding is performed using the same processes, parameters, and conditions. To evaluate the welding potential of solid-state-recycled alloy, tensile tests, microhardness tests, optical metallography, and scanning electron microscopy, accompanied by energy-dispersive spectroscopy analysis, are performed.

Multi-Objective Welding Optimization for AA5052 Using Taguchi-Fuzzy Approach

<div>This study investigates the influence of tungsten inert gas (TIG) welding parameters on the dilution and hardness of AA5052 aluminum alloy. Employing Taguchi’s L27 orthogonal array, the research systematically explores the effects of current, voltage, and welding speed. Analysis of the experimental data utilizes signal-to-noise ratio, analysis of variance (ANOVA), and regression techniques. The study compares a traditional regression model with a fuzzy logic approach for result validation, finding that the latter exhibits marginally better predictive accuracy. Optimal welding parameters are identified as 150 A current, 20 V voltage, and 45 mm/s welding speed, yielding a maximum dilution of 52.81% and hardness of 145.3 HV 0.5. Current emerges as the most significant factor influencing both dilution and hardness. Microstructural examination, hardness profiling, and tensile testing of specimens welded under optimized conditions reveal a characteristic hardness distribution across the weld zones and ductile fracture behavior.</div>

Effect of adding borax on the Oxy-Acetylene Welding (OAW) process on tensile strength of ST42 steel

effect of adding borax on the Oxy-Acetylene Welding (OAW) process on tensile strength of ST42 steel

TIG welding process on IS 2062A steel of 5 mm plate, utilizing a 2.5 mm diameter tungsten solid wire as electrode along with direct current straight polarity and argon inert gas was employed for shielding purpose

The quality as well as efficient welding is crucial to fulfil the consumer satisfaction and getting returns from production, which is mostly depends on weld bead properties for any welding process, which is influence by the selected welding method and its process variables. So, the significant efforts are to choose the appropriate welding process in addition the process parameters as well as their level. In an atmosphere of welding different technique have been developed in last few decades, the demand of Gas Tungsten arc welding (GTAW) or Tungsten inert gas welding (TIG) has been increasing day by day owing to it has potential to fabricate multiple metallic materials (similar/dissimilar), quality joint, smooth modification for industrialization, higher efficiency, and low capital cost. However, published literature regarding research on TIG welding of IS 2062A steel is notably scarce. Detailed discussions on the optimization techniques exploring the impact of process parameters such as welding current, traversing speed, and gas flow rate on both weld quality and bead geometry in TIG welding of mild steel are conspicuously absent in prior works. So it is very crucial for quality joint to applied process optimization on TIG Welding parameters. The study focused on tungsten inert gas welding process on 5 mm thick plate of IS 2062A steel, utilizing a 2.5 mm diameter tungsten solid wire as electrode along with direct current straight polarity and argon inert gas was employed for shielding purpose. To streamline experimentation, a multi-response optimization technique was employed, using Taguchi's L16 experimental design method. Among several welding parameters, the significant parameters like current (I), traversing speed (S), and gas flow rate (Gf) were considered, others parameters were kept constant. The study measured various aspects of bead properties, including penetration, bead width, and depth of HAZ, along with HAZ hardness. The optimized parameter settings, derived from the signal-to-noise (S/N) ratio, has been validated as improved the weldment properties along with possess highest grey relation grade, which highlighting the effectiveness of the Grey-based Taguchi method in enhancing joints properties as product quality together with efficiency in manufacturing. Quantitative assessment via the analysis of variance method was conducted to determine the relative significance of each variable on the overall output characteristics of the weldment.

TIG Welding of EN AW-6082 Al Alloy: A Comparative Analysis of Filler Rods on Microstructural and Mechanical Performance

This study investigates the impact of different filler wires (ER5356, ER4043, and ER4047) on the microstructural and mechanical properties of EN AW-6082 Al alloy joints produced by tungsten inert gas (TIG) welding. Butt-welded samples with a single V-groove joint configuration were prepared using optimized welding parameters. The welded samples were subjected to visual inspection, microstructural analysis, hardness testing, tensile testing, and impact toughness evaluation. The results showed that all the welds were free of visible defects. Microstructural examination revealed that the ER5356 filler produced the finest grain structure of 18.03 ± 3 μm, while ER4047 resulted in the coarsest grains of 36.07 ± 5 μm. Correspondingly, the joints made with ER5356 exhibited the highest tensile stress of 278 ± 6 MPa, yield stress of 219 ± 5.4 MPa, hardness values of 72.7 ± 5 HV, and welding efficiency of 86.07%, whereas those made with ER4047 produced the lowest values. The hardness in the weld region was lower than that in the parent metal and heat-affected zone for all samples. However, ER4047 welds demonstrated superior impact toughness and strain-hardening capacity. The findings underscore the importance of filler metal selection in tailoring mechanical properties for high-performance applications.

A Study on the Effects of Welding Parameters on Weld Bead Geometry in TIG Welding Process of Zircaloy Fuel Pins Using Response Surface Methodology

This paper investigates influences of welding parameters on weld bead geometry in the tungsten inert gas welding process of Zircaloy-2. Initially, a “Definitive screening design” was employed for identifying the key factors affecting weld bead geometry. Subsequently, response surface methodology was utilized to generate an experimental matrix, and experiments were conducted to analyze the effects of each welding parameter on weld bead geometry. Mathematical models were developed using analysis of variance for two-weld bead geometrical parameters, and their validity was assessed by comparing experimentally obtained values with those predicted by the model. Finally, a dimensionless parameter, the aspect ratio, indicative of the weld quality, was optimized.

Investigations on the mechanical characteristics of Flux-Bound TIG-welded UNS S32760 Super Duplex Stainless Steel

In the current work, the mechanical properties of Flux Bound Tungsten Inert Gas (FB-TIG) welds on UNS S32750 Super Duplex Stainless Steel (SDSS) produced using three flux powders viz., Silicon Dioxide (SiO2), Titanium Dioxide (TiO2) and Vanadium Pentoxide (V2O5) are investigated. Initially, tension tests were conducted to analyse the yield strength, tensile strength, and percentage elongation of the three FB-TIG welds. The highest values of yield and tensile strengths were obtained for the TiO2 FB-TIG weld, with all the welds exhibiting very good yield and tensile strength values. Then the fracture toughness of the welds was investigated by impact testing at two different temperatures, i.e. (i) at room temperature and, (ii) at sub-zero temperature of -46 °C, which is close to the Ductile to Brittle Transition Temperature (DBTT) of the SDSS base metal. The maximum value of room temperature fracture toughness was obtained for the TiO2 flux and the maximum sub-zero fracture toughness was obtained for the SiO2 flux. Furthermore, the fracture surfaces of the materials were examined by SEM fractographic examinations to analyse the mode of fracture. At the sub-zero temperature, the FB-TIG weld with V2O5 flux showed a mixed mode of fracture exhibiting both ductile and brittle mechanisms.

Swing and Electrode Diameter Effects on Toughness and Hardness of Stainless Steel 304 MIG Welding Results

Welding is one of the commonly used methods for joining metals. One of the welding techniques frequently employed is MIG welding (Metal Inert Gas welding). This type of welding is typically used for joining stainless steel. Consequently, many factors need to be analyzed to achieve optimal welding results. The objective of this research is to investigate the influence of swing variation and electrode diameter on hardness, toughness, and macrostructure from the welded stainless steel 304 using MIG welding. The research results showed the highest toughness test results with a 2.0 mm electrode diameter and a zig-zag swing of 0.459 J/mm2, while the lowest toughness test results were obtained with a 2.6 mm electrode diameter and a spiral swing of 0.201 J/mm2. The highest hardness test results were observed with a 2.6 mm electrode diameter and a zig-zag swing in the Heat Affected Zone (HAZ) at 292.0 kg/mm2, whereas the lowest hardness test results were obtained with a 2.0 mm electrode diameter and a zig-zag swing in the welded metal at 203.6 kg/mm2. The widest HAZ occurred with the spiral swing variation and a 1.5 mm electrode diameter, resulting in a HAZ width of 1.92 mm, while the narrowest HAZ of 1.25 mm occurred with the spiral swing variation and a 2.0 mm electrode. Thus, it can be concluded that the electrode diameter variation affects the results of toughness, hardness, and macrostructure tests.

Numerical investigation of the influence of pulse frequency on the weld pool size in pulsed current TIG welding

This study simulates the pulsed current tungsten inert gas (TIG) welding process to investigate the transient development of the weld pool in a 4 mm thick aluminum sheet, focusing on the effects of pulse frequency on the weld pool size. Two pulsed currents, 230 and 180 A, with a 30% background current, were examined. The 230 A current achieved full, while the 180 A resulted in partial penetration. Five pulse frequencies (1, 4, 10, 20, and 50 Hz) were analyzed. A numerical model was developed to compute heat and current fluxes on the workpiece surface. The arc profile shifted from a bell shape in high-frequency cycles to a conical shape in low-frequency cycles. The heat and current fluxes served as inputs to another model that simulated weld pool behavior for both direct and pulsed current TIG welding. The results showed that weld pool size decreased in pulsed current TIG welding. At 230 A, full penetration changed to partial penetration under pulsed current. At 1 Hz, sufficient time was available for solidification during the low-cycle period, but at 50 Hz, the weld pool remained liquid. As pulse frequency increased from 1 to 50 Hz, the weld pool depth decreased significantly, with a reduction from 2.4 to 0.9 mm at 230 A and from 1.1 to 0.34 mm at 180 A. Convection in the weld pool was influenced by temperature and was strongest at higher temperatures. The decrease in weld pool size was most pronounced between 1 and 10 Hz, stabilizing between 20 and 50 Hz. Validation against experimental macrographs demonstrated good agreement with the simulations.

Spatial mapping of the localized corrosion behavior of a magnesium alloy AZ31B tungsten inert gas weld

Spatial mapping of the localized corrosion behavior of a magnesium alloy AZ31B tungsten inert gas weld

Stress Corrosion Behavior of MIG Welded Joints of 6082-T6 Aluminum Alloy at Different Temperatures

6082-T6 aluminum alloy is a commonly used aluminum alloy material in the field of rail transit because of its good molding properties, high mechanical properties, excellent corrosion resistance and weldability. In the high temperature and humid environment, the temperature change is bound to affect the stress corrosion resistance of the aluminum alloy and their welded joint. However, the influence mechanism of temperature on its stress corrosion resistance has not been explained in the existing research. In this paper, the mechanical properties and stress corrosion behaviors of melt-inert gas welded (MIG) 6082-T6 aluminum alloy welded joints were systematically studied under various temperatures condition. Results indicated the temperature scarcely affected stress corrosion cracking susceptibility index (PSCC) of base metal, while significantly affected the welded joint and higher temperature caused lower PSCC. After slow strain rate tensile test, a corrosion layer was formed, which was a typical brittle-toughness mixed failure, and the degree of brittleness increased with the increasing of temperature. Electrochemical analysis showed that corrosion resistance of the joint slightly decreased due to aluminum alloy accelerated dissolution caused by increasing of temperature. The proposed research will provide a theoretical basis for solving aluminum alloys used in rail transit, ship accessories and other industrial fields.

Dimensional Analysis and Validity of Uniaxial Residual Stress Distribution for Welded Box Sections

This paper investigates the residual stresses induced by metal inert/active gas (MIG/MAG) welding in normal strength steel box sections, focusing on the validity of uniaxial residual stress assumption. Advanced manufacturing simulations are conducted using deterministic uncoupled transient thermomechanical analysis with a double-ellipsoidal heat source model, employing 8-node solid elements and material models calibrated for extreme temperatures per EN 1993-1-2. A comprehensive parametric analysis investigates the effects of primary welding variables, such as heat source power and welding speed, alongside geometric parameters of the heat source model using random Latin hypercube sampling technique in the analyzed parameter set. The relationship between the size and shape of the characteristic isotherms, i.e., the aspect ratio and the Rosenthal number, underscores that the analyzed welding heat sources are in the fast regime with the validity of uniaxial residual stresses based on the analytical assumption (minimal values are AR = 9.94 and Ro = 30.47). The validity and limitations of uniaxial residual stress assumptions for 59 welded and 51 heated box sections are critically evaluated by using the finite element model-based stress triaxiality parameter. Results confirm that longitudinal residual stresses dominate typical MIG/MAG welding applications, supporting the application of uniaxial residual stress models in advanced structural design by neglecting in-plane and through-thickness residual stresses. Conversely, three-dimensional residual stress state dominates under conditions such as preheating or thermal straightening.

Selection of the Process of Arc Welding of Sealing Surfaces of Power Valves with a Consumable Electrode in the Shielding Gas

Introduction. One of the main requirements to the methods of weld overlay of sealing surfaces of power valve trim parts is to obtain a high-quality wear-resistant pad with minimal penetration and optimal process performance. Currently, arc, electroslag, plasma, beam, induction and other surfacing techniques have been developed and introduced into production. However, the influence of various arc welding processes with a consumable electrode in shielding gas on the geometric parameters of weld beads and metal hardness of sealing surfaces is understudied. The presented research is intended to fill this gap. The objective of its authors is to select such a process of arc welding of beads on parts of the power valve trim with a consumable electrode in shielding gases, which would provide the best workability of the deposited metal.Materials and Methods. Arc surfacing with a consumable electrode in a mixture of gases was performed on steel plates. The welding torch was moved in a straight line, without transverse oscillations, using the FRC-9 mechanism (Fronius). A microprocessor-controlled inverter-type digital current source TransPulsSynergic 3200 CMT (Fronius) was used as the power supply. The following welding processes were analyzed: MIG/MAG process with self-regulation (Standard mode), synergic process of MIG/MAG method (Synergic mode), short arc process with mechanical separation of electrode metal droplets (CMT-ColdMetalTransfer), and synergic pulse-arc process (PulseSynergic). The short-cut process of bead surfacing was evaluated by the stability of the values of the energy parameters of the bead surfacing mode in time at the same electrode wire feed rates, which were recorded by oscilloscopes, as well as by comparing the geometric characteristics of the deposited beads and the hardness of the deposited metal.Results. The analysis of experimental data of the geometrics of the weld beads and their complex dimensional characteristics made it possible to establish that the welding engineering requirements for the welded beads are most fully met by long-arc surfacing by the PulseSynergic pulse-arc process.Discussion and Conclusion. The study and the resulting data make a certain contribution to solving the problem of the influence of arc welding processes on the parameters of weld beads and on the hardness of the metal of sealing surfaces. A detailed analysis of the modes of arc surfacing of beads with a consumable electrode in shielding gases on the trim parts of power valves can be used in further research on this topic. The conclusions of the authors will not only provide considerable theoretical assistance to scientists, but will also make adjustments to the activities of practitioners.

Comparative analysis of microstructural and nanomechanical characteristics of MIG and TIG-MIG hybrid welded inconel 718 and AISI 316 with steel and inconel fillers

The joining of Austenitic Stainless Steel (AISI 316) and Inconel (IN718) was carried out using Metal Inert Gas (MIG) welding and hybrid TIG-MIG welding with Inconel (IN625) and steel fillers. The resulting weldments were examined for their microstructural and compositional characteristics, elastic modulus, and nano-hardness using optical microscopy, X-ray diffraction, and nanoindentation techniques. The results indicated that the base metal IN718 exhibited higher hardness and elastic modulus compared to AISI 316. Additionally, the formation of the δ-Ni3Nb phase was observed in both MIG and hybrid welding processes using IN625 filler, along with austenitic matrices of Fe and Ni. When steel filler was used, it led to the development of a finer cellular, columnar, and equiaxed dendritic microstructure compared to the IN625 filler. The highest hardness in the heat-affected zone (HAZ) of IN718 was observed in hybrid welding with the steel filler, which was 7% and 5% higher compared to MIG welding with IN625 and steel fillers, respectively. Moreover, the maximum hardness in the fusion zone (FZ) of 4.55 GPa was achieved in MIG welding with the steel filler, which was 36% and 69% higher compared to hybrid welding with steel and IN625 fillers, respectively. The hardness varied between 2.74 GPa and 3.62 GPa in the HAZ of AISI 316 for MIG welding with steel and IN625 fillers, respectively. The elastic modulus was found to be 213 GPa in MIG welding with IN625 filler and 214 GPa in hybrid welding with steel filler. Pile-up behavior was observed around the nanoindents for all weldments obtained in both MIG and hybrid welding using steel and IN625 fillers.

Оценка качества и механических свойств получаемых слоев металла из низкоуглеродистой стали методом WAAM с использованием дополнительной механической и ультразвуковой обработки

Introduction. Additive manufacturing is a technology that enables three-dimensional (3D) components to be printed layer by layer according to digital models. Completely different from traditional manufacturing methods such as casting, forging, and machining, additive manufacturing is a near net shape manufacturing process that can greatly enhance design freedom and reduce manufacturing runtime. The material processing challenges in Wire and Arc Additive Manufacturing (WAAM) are related to achieving performance metrics related to geometric, physical, and material properties. Tight tolerances and stringent surface integrity requirements cannot be achieved by utilizing stand-alone AM technologies. Therefore, WAAM parts typically require some post-processing to meet requirements related to surface finish, dimensional tolerances and mechanical properties. It is therefore not surprising that the integration of AM with post-processing technologies into single and multi-setup machining solutions, commonly referred to as hybrid AM, has become a very attractive proposition for industry. The purpose of the work is to evaluate the quality and mechanical properties of the resulting metal layers of mild steel by WAAM method using additional mechanical and ultrasonic processing. Research Methods. To conduct the experiments, a set of welding equipment was used — a single-phase inverter device KEMPPI Kempomat 1701, designed for welding with wire in shielding gases. A mixture of argon and carbon dioxide (80 % argon and 20 % CO2) was used as a shielding gas. SV-08G2S (0.8 C-2 Mg-Si) wire was used as the surfacing material. A plate made of steel St3 with overall dimensions 150×100×5 mm was used as a base for surfacing. The surface of the plate before surfacing was thoroughly cleaned from the layer of oxides, oil, rust and other contaminants. For this purpose mechanical cleaning of the surface was used with BOSCH abrasive wheel with a diameter of 125 mm diameter and a grit size of 120. Before surfacing the surface of the product was degreased with white spirit. The gas flow rate was set at 8 dm3/min. To select the optimal wire feed rate and volt-ampere characteristic, surfacing was performed at each adjustment step of wire feed rate, and voltage. Mechanical statistical tensile tests, chemical composition analysis and metallographic studies were also performed. Results and Discussion. Gas porosity is a typical defect that occurs during the WAAM process and should be eliminated because it adversely affects the mechanical properties. Initially, gas porosity leads to a reduction in the mechanical strength of the part due to damage from microcrack formation. In addition, it often causes the surfaced layer to have worse fatigue properties due to the spatial distribution of different shape and size structures. In our experiments we found that a wire feed speed range of 5–6 m/min is optimal. Increasing the flow rate of shielding gas in the range of 8–14 l/min allows reducing porosity in the surfaced metal to almost zero. The mechanical properties of the surfaced beads show that the average value of yield strength after machining is higher than that of unprocessed specimens. The data obtained from these experiments are in good agreement with those reported in the literature. The presented results can be used in real WAAM technological processes.

Enhancing Welding Productivity and Mitigation of Distortion in Dissimilar Welding of Ferritic-Martensitic Steel and Austenitic Stainless Steel Using Robotic A-TIG Welding Process

The P91 martensitic steel and 304L austenitic stainless steels are two mainly used structural steels in power plants. The major problem in conventional multipass tungsten inert gas (TIG) welding of P91/304L steel is high heat input and joint distortion, increased cost and time associated with V groove preparation, filler rod requirement, preheating and welding in multiple passes, and labor efforts. Hence, in this study, a novel approach of robotically operated activated flux TIG (A-TIG) welding process and thin AlCoCrFeNi2.1 eutectic high entropy alloy (EHEA) sheet as the interlayer was used to weld 6.14 mm thick P91 and 304L steel plates with 02 passes in butt joint configuration. The joints were qualified using visual examination, macro-etching, X-ray radiography testing and angular distortion measurement. The angular distortion of the joints was measured using a coordinate measuring machine (CMM) integrated with Samiso 7.5 software. The quality of the A-TIG welded joints was compared to the joints made employing multipass-TIG welding process and Inconel 82 filler rod in 07 passes. The A-TIG welded joints showed significant reduction in angular distortion and higher productivity. It showed a 55% reduction in angular distortion and 80% reduction in welding cost and time compared to the multipass-TIG welded joints.