Residual Stress Prediction during TIG and MIG Welding Process of Steel - A Review

In this study, a forensic review of residual stress predictions and its impact on welded joints especially the steel pipes during the Tungsten inert gas welding and metal inert gas welding processes were reviewed. It was established that in the case of MIG welding, the effect of residual stress can be reduced after treatment. In the case of TIG welding process, increase in current will lead to deformation and residual stresses. Estimating the residual stress is a challenging task. It is common to predict residual stress using a notch stress intensity factor, a numerical simulation approach coupled with a thermal-mechanical finite element model. Thus, adequate design in welding parameters will help in the optimization of the process to achieve a safe and reliable welded joint during TIG and MIG welding process.


Introduction
Welding is a fabrication technique which requires the joining of two or more metals together to form a joint or components.This joining technique involve melting of the surfaces to be joined via several parameter selection and optimization.Some of the important parameters used in the tungsten inert gas (TIG) and metal inert gas (MIG) welding include welding speed, welding voltage, welding current and the welding gas flow rate [1].This study analyses the factors influencing residual stress formation during TIG and MIG welding, including welding parameters, material properties, and process variations and evaluates the effectiveness of different numerical simulation and experimental techniques in predicting residual stresses during TIG and MIG welding, aiming to identify gaps and areas for improvement.Some advanced welding process like electron beam welding is associated with narrow weld zones with evidence of reduced heat affected areas as well as distortions which could be as a result of the weld.Residual stresses are reduced in this condition, and it is quite detrimental to the structural properties of the components which contribute to the unsafe conditions of the structures [2].According to the study by Sun et al. [3] strain hardening, phases and temperature related strain hardening affects the residual stress during a single pass welding of joints especially in structural steel.Experimental and numerical investigations showed that the plasticity of materials has the capacity to influence the prediction of residual stress during welding.In fact, it was established in the study that the magnitude of the residual 1322 (2024) 012008 IOP Publishing doi:10.1088/1755-1315/1322/1/012008 2 stress in the base metal close to the weld region in the plate is higher for isotropic hardening.However, it is smaller when kinematic hardening model is used.Furthermore, it was affirmed that the isotropic hardening model predicts residual stress more during welding process.
More so, the variation in the temperature dependent strain hardening slopes of the developed phases i.e., austenite and bainite has no effect on the prediction of the welding residual stress.In the study of Luo et al. [4], it was reported that most engineering structures especially bridges are constructed using orthotropic steel deck due to its light weight and adequate strength.However, it is associated with fatigue failure at the welded joint of the steel.Thus, to evaluate the fatigue damage, notch stress intensity factor is used in the characterization of the mechanical properties.Thus, in the study, notch stress intensity factor model was formulated for the condition of the rib to deck welded joints under the influence of the loading modes.Finite element approach was further deployed to establish the understanding of geometrical factor on the notch stress intensity factors.These parameters include the penetration rate of the weld, weld height, deck toe flank angle, and the thickness ratio of the plate.
From the result, the stress distribution was evaluated using the notch stress intensity factor for the joint.More so, the maximum error was obtained as 9.5% which implies that the prediction using the notch stress intensity factor agrees with the finite element approach.Thus, this formula provides useful insight for the determination of the stress distributions in welded joints.In the same vein, Moarrefzadeh et al. [5] developed a technique for the investigation of the residual stress on the crack propagation rate which worked on the concept of prediction elastic-plastic model during welding process.It was reported that this method is efficient in the determination of the residual stress distribution as a result of the growth of crack and the evaluation of the stress intensity factor.
According to Pavan et al. [6] residual stresses and distortions are usually as a result of the constraints experienced by weld metal shrinkage of the base materials.However, adequate selection of welding process can help in minimizing the residual stresses and the distortions.Thus, this study considered the use of hybrid welding process which comprises laser MIG and hotwire TIG welding techniques.Hence, a perfect weld of 316L (N) stainless was achieved under the application of low heat.The experimental and numerical results revealed that the residual stress distribution was substantial in the MIG welding compared to the TIG weld joint.More so, the extent of external restraint excellently influences the magnitude of residual stress distribution as well as distortion.Samadi et al. [7] carried out a quantitative evaluation of the residual stress and fatigue behavior of T-type welded joints which was fabricated using multi-pass weld in varying directions.The results showed that there was increase in the compressive residual stress when single weld pass was used compared to double and triple weld-pass.More so, the fatigue life was established to improve with increase in the weld passes.Thus, to determine the strength of welded joint, multi-pass welding in varying directions played a major role.
According to the study by Sun et al. [8], it was established that welding residual stresses and deformations can be determined experimentally based on the fundamental knowledge.However, a major problem is that experimental trials are time consuming and complex and expensive as well because of the equipment characterization cost.Also, the experimental results are usually subjected to the equipment used in welding and the methods as well as the geometries of the specimen.Hence, it is impossible for the result to be reliable when there is variation in the experimental parameters.Hence, numerical analysis has proven to be efficient via parameter optimization, thus, making it easy to obtain adequate mechanical properties during the welding process.To this end, the study deployed a numerical simulation approach coupled with thermal-mechanical finite element model to investigate the residual stresses, distortion, and temperature field in a weldment of NV E690 using laser arc welding process.For proper validation of the applications, the residual stresses, distortion, and the shape of the weld pool were simulated and measured experimentally.The result demonstrates that there was agreement between the geometry of the weld bead and the dimension of the weld pool indicating the evidence of the combined heat source.Furthermore, there was higher tensile stress distribution in the zone of fusion and heat affected zones.In addition to this, the result of numerical and experimental comparisons showed that the model developed can be effectively used to determine the residual stress and the distortions of welding process.In the study of Ilman et al. [9], a stress relieving treatment technique known to be static thermal tensioning was deployed during the application of MIG welding process.Sodium chloride solution of 3.5% concentration was used in the determination of the fatigue crack test without an inhibitor.The study further applied stress ratio and frequency of 0.1 and 8 Hz respectively while the residual stress was determined using neutron diffraction technique.
More so, the corrosion result was carried out using potentiodynamic.The result revealed that there was improvement in the corrosion performance due to the introduction of residual stress relieve treatment.Also, the combination of the compressive stress as well as the repassivation of the weld joints helped in inhibiting the fatigue crack propagation.According to James et al. [10], the local surface environment influences fatigue and this environment consist of the residual stress, stress concentration and the gradient of hardness as well as the toe position which of the weld cross section.The relationship between these factors usually result variation in the fatigue performance of welded joints.
The research on residual stress prediction during TIG and MIG welding processes of steel makes notable contributions to sustainable energy, energy materials, and applications in the following ways: Resource efficiency; by improving understanding of welding-induced residual stresses, the study contributes to the development of optimized welding processes.This efficiency aids in minimizing material waste, reducing energy consumption, and promoting sustainable resource utilization in the fabrication of energy-related structures and components.Structural integrity enhancement: accurate prediction and mitigation of residual stresses enhance the structural integrity of welded components in energy applications.This is particularly crucial in energy infrastructure such as power plants and renewable energy systems, ensuring prolonged lifespan and reduced maintenance requirements.Others are material performance optimization, safety and reliability, environmental impact reduction, and innovation in welding technology which can lead to the development of advanced welding techniques, contributing to more sustainable and efficient manufacturing processes in the energy sector.

Residual stresses in MIG Welding Process
Welding is the main technique for fabricating numerous components like bridges, ships, trains, and automobiles.The assembly process of the aforementioned machinery/equipment involves welding of different components.For instance, in the manufacture of mufflers which is an important component in the automobile, welding is associated with deformation as a result excessive temperature during the process.Hence, the welding deformation could cause dimensional problems which has negative impact on the accuracy of fabrication as well as the external features.
The dimensional problems also tend to increase the cost of fabrication of the structures.While it is impossible to eliminate the distortion, welding prediction of the distortion could help in minimizing the likely problems.More so, various component parts of the muffler are assembled using the most prevalent arc welding process which is MIG welding Chaurasia et al. [11].To this end, Lee et al. [12] established that the distortion which occur during MIG welding of the automobile muffler can be traced to the thermal deformation during the process.Thus, the study focused on the prediction of the deformation and the residual stress using SYSWELD software.the stud compared the result of the cross section of the pool which was predicted via numerical analysis and compared to the experimental results.It was confirmed that compressive stresses were developed at some region away from the weld while high tensile stress was observed in the zones near the weld.Furthermore, large amount of stress was observed at the heat affected zone and the fusion zone.the weld zone was characterized by expansion and extraction deformation because of the heating and simultaneous cooling.Hence, stresses occur via the solidification of the molten metal pool and the base metal shrinkage.It is noteworthy to say that the welding residual stress has impact on the low temperature crack, brittle fracture strength and buckling strength of the welded structures.
According to Ilman et al. [13], hybrid welding involving laser-MIG is a complex process which involves two different sources of heat combined for the welding process.Thus, it becomes difficult to assess the and control the process.This will cause random flow of melted metal which could be because of the impact of the droplet on the molten pool causing instability in the keyway.Furthermore, combination of the laser and arc welding process could result in defects like cracks, undercut as well as inadequate weld penetration.Also, residual stress would be difficult to control, hence this contributes to the accident occurrence in the industrial machinery/equipment. [13] reported that lightweight components are required in the fabrication of ship structures to increase performance and saving of fuel.However, the welding of such thin sheets is associated with distortions and residual stresses.Thus, this study aimed to eliminate the residual stress and distortion by using a static thermal tensioning on the weld zone during MIG welding of AA5083 metal.
Distortion measurement and residual stresses were carried out using neutron diffraction technique and fatigue crack growth test.As well as scanning electron microscopy.The results showed that there was an increase in the temperature of heating which caused the convex longitudinal to be out of plane distortion and the smallest longitudinal out of plane distortion was achieved at 200 degrees Celsius.In the same vein, Pratihar et al. [14] established that neutron diffraction has been deployed in the measurement of the residual stress field of MIG-welded Al-2024 and Al-7150 alloy compact tension specimens.It was reported that the calculated resultant residual stress was compared to the original welded plate before the machining of the specimens were carried out.Ilman et al. [15] deployed MIG welding to join AA5083 alloy plates to reduce the distortion and residual stresses as well as the propagation of fatigue stress which occur due to the increase in heat input.Two methods of the residual stress and distortion minimization were deployed which include heat sink and static thermal tensioning treatments during the welding.Two torches were located at a distance of 100 mm apart during the MIG process.Also, residual stress and the distortion microstructure, distribution of hardness, tensile strength, and crack propagation due to fatigue were characterized and evaluated.The results revealed that heat sink reduced the crack propagation rate of the weld.Thus, the fatigue crack propagation inhibition in the heat sink treated weld could be associated with its fine grained equiaxed structure as well as the compressive residual stress.The beneficial aspect of the heat sinks and the static thermal tensioning in reducing welding residual stress and distortion could be associated to the thermal tensioning due to the variation in the temperature gradient.
In a study by Wang et al. [16], it was reported that the residual stresses and distortion of the welded joints could be analysed via a numerical simulation approach.Thus, the study proposed a sequentially combined thermo-mechanical and mechanical simulation to characterize the mechanical properties of the welded joint using a finite element approach.The transient temperature and the residual stress were analysed via this process and conducted to build mechanical simulation model using a detailed geometric characteristic and the residual stress.The result showed that the stress distribution of the welded joints revealed fracture mode.Also, the presence of weld reinforcement caused increase in the shear stress under the tensile condition, thus, the fracture morphology has equiaxed and elongated dimples [14].
However, after the removal of the reinforcement, the mechanism became trans granular and intergranular mix fracture at the welded zones.Figures 1 and 2 showed the fracture morphologies of the reinforcement and smooth samples as revealed via the scanning electron microscope [14].From the result, it could be observed that the fractured surface of the reinforcement appeared flat and this the reason behind the transgranular fracture result from the deformation damage of the grains.However, in the case of the smooth specimen Figure 1(b), the fracture morphology is not uniform, showing that it is characterized by transgranular and intergranular fracture.In addition to this, the variation in the pattern of fracture is attributed to the locations of the fracture [16].On the part of the morphologies of the dimples figure 1b, it could be observed that the reinforced specimens are a mixture of elongated and equiaxed dimples in which the dimples are elongated the direction of the shear stress which are shallow, large, and distributed randomly.However, the dimples of the smooth samples are more of the equiaxed, deep, small, and evenly distributed as revealed in Figure 2b.thus, the reason for the variation is in the existence of the weld reinforcement which changes the distribution of stress of the reinforcement sample under the influence of tensile stress condition.More so, the smooth sample was subjected to more of the normal stress.Huang et al. [17] Developed an innovative 3D numerical model using the transfer of droplets, metallic vapour, and molten pool dynamics to investigate flow of the melt and keyhole-induced pore formation during the MIG and lasermetal hybrid welding process [18].
The study mimics the entire process of the generated bubble, movement, shrinkage and captured by the front solidification of bubbles in the molten metal.The result revealed both counterclockwise and a clockwise eddy both in the upper and lower regions of the molten pool respectively which was respectively driven the recoil pressure as well as the metallic vapour.Khoshroyan et al. [18] investigated the temperature distribution and the residual stresses as well as the distortion in aluminium alloy Al6061-T6 plate during the MIG welding process using Ansys software.The study considered the material properties such as temperature-dependent and the filler metal which was added to the workpiece using the element birth and death method.Using three different current modes and two different speeds as well as sequences, the residual stress and distortion distribution were analysed.The result showed IOP Publishing doi:10.1088/1755-1315/1322/1/0120086 that there was increase in the welding speed which led to a decrease in the vertical deflection of the plates, shrinkage, distortion, and the lateral stiffener.However, there was increase in the longitudinal stress in the plate and stiffener [18].
Additionally, the increase in current resulted in the increase in the residual stress and deformations in the plate as well as the stiffener.According to Zhen et al. [19], finite element method could be used to carry out a reliable simulation of residual stress in aluminium alloy welds and other types of metal welds.The theories of heat conduction and welding heat sources were proposed in mathematical form.To integrate the impact of molten pool and keyhole in laser welding, the study adopted the combine heat sources model of Gaussian surface heat distribution source and cylindrical source of heat to deal with the actual situation.Furthermore, the welding residual stress and deformation were evaluated in the Ansys calculation using pretention and under pretention conditions and the results were compared.The result showed that there was close agreement in the simulation result and thus, good in predicting the residual stress in the aluminium alloy of welding film [20].

Residual stresses in TIG Welding Process
According to Wang et al. [20], aluminium alloy is usually deployed in the manufacturing of cryogenic fuel tank for vehicle launch and the manufacturing process is via arc welding.The mechanical properties of welded joints are always lower compared to that of the base material due to the non-uniform heating and cooling temperature during the welding process.The filed temperature which is non-uniform results in the welding of residual stresses and deformation.This can affect the performance and reliability of welded components.According to the study, the welding joints represent a weak part of the launch vehicle and to gain access to the load bearing capacity of the joints, there is a need for the procedure qualification using ISO standard 15614-2:2005.The standard involved preparations of the welding joint with dimensions 300×300 for a butt welding.Some important questions include the varying residual stress that evolve after cutting the samples for the tensile tests as well as whether the tensile samples can represent the original components.
Chen et al. [21] established that TIG welding is generally deployed in the joining of different automobile and aerospace components.This includes the rotating blade, vane, and the control arm.In most of this process, there are high and localized heating accompanied by rapid cooling during the process and the process equally exert complex thermal and mechanical loading on the components which result to residual stress field.This, however, increase of failure which is time dependent via crack initiation.Within the engineering context, designing for structural integrity, reliable operations require the evaluation of residual stress in the component parts.Thus, this study examined a TIG filled weldments in single crystal superalloy components having a nearly cylindrical geometry was considered.There was good agreement between the results of hoop and radial tensile residual stresses which was observed at the boundary of the base and filler metal.
Similarly, Prasad et al. [22] reported that there are numerous parameters which affect the TIG welding especially during the circumferential TIG welding that is widely deployed in the oil and gas, power stations and the piping industries.The study further reported that 3D numerical simulation code was used in predicting the residual stress distribution for a circumferential TIG welding.It was discovered that increased amount of residual stress was found around the weld pool due to the nonuniform distribution of thermal and plastic strain.In the study of Xu et al.Xu et al. [23] two-part conical models and cylindrical models were deployed to predict the thermal stress of laser beam welding as heat sources, while double ellipsoid heat source model was deployed to simulate the TIG welding process.The thermoelastic stress strain behavior was characterized using a non-linear mixed hardening model as well the annealing temperature.The numerical result was validated via experimental means and there was excellent agreement between the predicted and the experimental results in terms of the residual stress.Figure 3 and 4 showed the residual stress plots of both the laser beam welding and the TIG welding process.It can be observed that there was good prediction and there was good agreement in the residual stress measurement.Also, a V-type distribution was observed in the hoop and axial residual stresses.From Figure 3, in the weld and heat affected zones, the hoop and axial residual stresses exhibited a V-shape distribution.The maximum hoop tensile stress occurs at the center of the weld, however, the residual stresses which are axial were termed compressive stress both at the weld and heat affected zones.In the same vein, from Figure 4 there was an agreement between the calculated residual stresses and the experimental results.While at the fusion zone, the hoop residual stresses are tensile, it however, reduces to compressive in the heat affected zone. in the axial state, there was a transition from compressive stress to tensile stress in the heat affected zone which was away from the center of the weld [25].In the study of Wu et al. [24], it was established that circumferential TIG welding is a prominent technique is very prominent in the welding of pipes.However, they are associated with residual stresses which occur at the weld bead.This can be traceable to the localized heating and the corresponding rapid cooling during the welding process.Also, a major factor among various residual stresses is the tensile welding residual stress.This factor [25] usually contributes to fatigue, stress corrosion, brittle fracture, and cracking [26].Thus, its accurate prediction and control of the weld residual stresses during the design and the process of manufacturing is quite important.Circumferential TIG welding is associated with complexities in the welding process.The prediction of the residual stress is quite difficult.Hence, since there is an improvement in the simulation of power and computer storage capacity, there is a need for the use of numerical simulation approaches.Rissaki et al. [27] also reported that residual stresses are generated because of uneven volumetric variations in the welded samples during solidification as well as cooling.More so, increase tensile residual stresses could lead to fatigue, fracture, and stress corrosion cracking, while buckling strength is associated with the compressive residual stress [28][29].Although, the compressive residual stress may be useful in the prevention of stress corrosion cracking as well as the fatigue crack propagation.Thus, structural integrity of welded joints can be assessed via the estimation of the residual stress [30].

Conclusion
Residual stress is associated with welding processes and in most cases welding repair.This could threaten the safety of the welded pipes used in the power plants reactors, stainless steel pipes and in the pressure vessels.Thus, this study focused on the prediction of residual stress during the TIG and MIG welding processes and to determine its impact on the welded joint as well as the overall reliability of the pipes.From the review, it was established that residual stresses could result into fatigue damage and stress corrosion especially the tensile residual fatigue test.Thus, minimizing or its elimination will help the reliability and safety of weldments.
Findings from the study include variability in methods; there is a significant diversity in numerical simulation and experimental methods used for predicting residual stresses.Finite Element Analysis (FEA) is commonly employed, but there is a need for standardization and comparison of different techniques.Influence of welding parameters such as heat input and travel speed, have a substantial impact on residual stress formation in steel weldments.Understanding and controlling these parameters are crucial for managing residual stresses effectively.The material properties of steel, including thermal conductivity and mechanical characteristics, play a critical role in determining the magnitude and distribution of residual stresses.Further exploration of the interplay between material properties and welding-induced stresses is necessary.
Validation of numerical models against experimental data remains a challenge.The review identifies the importance of developing robust validation techniques to enhance the reliability and accuracy of residual stress predictions.The influence of welding process variations on residual stress distribution requires further investigation.Exploring the effects of changes in welding conditions on the final stress state is essential for refining predictive models.Existing models demonstrate varying degrees of applicability to different welding scenarios.Recognizing the limitations of current methods and proposing improvements will contribute to more accurate predictions in diverse welding applications.The findings emphasize the need for future research to address gaps in understanding and predicting residual stresses during TIG and MIG welding of steel.Potential areas for improvement include refining numerical models, enhancing experimental validation techniques, and developing strategies for mitigating residual stresses in welded structures.

Figure 3 .
Figure3.Variation of residual stress of laser beam welding with distance to weld centerline.[23]

Figure 4 .
Figure 4. variation of residual stress of TIG welding with distance to weld centerline.[26]