Welding Temperature Field Research Articles

Numerical simulation of GTAW for ZW61 magnesium alloy thin plates: Coupling the finite element method with the cellular automata method

ZW61 magnesium alloy has a wide range of application prospects as a lightweight green engineering material. In this paper, the temperature field and microstructure of gas tungsten arc welding (GTAW) for ZW61 magnesium alloy are simulated by the finite element method and the cellular automata (CA) method. The results show that the microstructure in the center of the fusion zone (FZ) is all equiaxed grains affected by compositional supercooling. While at the edge of the molten pool, the crystals produced by associative crystallization evolve into columnar grains after undergoing competitive growth. Furthermore, the temperature field of the molten pool alters as the welding heat input increases. Especially, the temperature gradient behind the molten pool slows down. Thus, the cooling rate during solidification of the molten pool decreases, increasing the size of the weld microstructure. Meanwhile, solute concentration plays an essential role in the weld microstructure evolution. The rise in Zn content both refines the size of the equiaxed grains and inhibits the growth of the columnar crystals. Moreover, the experimental results of the thermal cycling curves and the FZ microstructure exhibit minimal error with the simulation results, verifying the reliability of the model.

КОМПЬЮТЕРНОЕ МОДЕЛИРОВАНИЕ ТЕМПЕРАТУРНЫХ ПОЛЕЙ В СВАРНОМ ШВЕ ПРИ ИЗМЕНЕНИИ ТЕХНОЛОГИЧЕСКИХ ПАРАМЕТРОВ СВАРКИ ТРЕНИЕМ С ПЕРЕМЕШИВАНИЕМ АЛЮМИНИЯ И МЕДИ

This paper discusses numerical modeling of temperature fields in friction stir welding (FSW) of aluminum (AD1) and copper (M1). A three-dimensional thermomechanical finite element model based on the coupled Euler-Lagrange (CEL) approach is used. The paper models and experimentally confirms the influence of FSW parameters on the distribution and peak temperature values in weld zones. The maximum temperature values are observed on the copper side. This is due to the high thermophysical properties of copper compared to aluminum. Changing the rotation speed of the welding tool from 800 rpm to 1000 rpm leads to an increase in the peak temperature from 492 °C (800 rpm) to 692 °C on the side of the copper plate (1000 rpm). The maximum discrepancy between the calculated and experimental temperature curves does not exceed 9%, which is quite acceptable for assessing the temperature field.

Tensile-shear mechanical properties of friction stir spot weld bonding hybrid joint in welding prior to and after adhesive curing for vehicle using

This research proposed a temperature-controlled friction stir spot weld bonding process as a solution to the issues of adhesive carbonization and weld impurities in the traditional combination of friction stir spot welding and adhesive bonding. A comprehensive investigation was conducted, including the establishment of a simulation model using the DFLUX subroutine to analyze the welding temperature field and the implementation of an overflow groove to separate the weld from the adhesive. The microstructure and mechanical properties of the joint were examined in the joint of welding before and after the adhesive curing process. The results demonstrated significant improvements in the failure load of the hybrid joints, with increases of 57.4 % and 27.7 %, compared to the welding joint. Additionally, the failure mechanism of the hybrid joint was elucidated by analyzing the fracture morphology.

Behavior of reinforced CHS T-joints by welding collar plates under load

The paper presents a comprehensive test program on collar plate reinforced CHS T-joints under different preload conditions, in order to investigate the effect of preload and welding thermal on reinforced joints. A total of four specimens, including specimens with and without preload when the collar plates were welded, were tested under brace axial loading. The test results, including welding temperature field, development of strain as well as welding residual deformation during the welding process are measured and presented in this paper. Furthermore, the failure model and compressive strength of the collar plate reinforced T-joints were determined. The test results demonstrated that the localized high temperature and rapid attenuation are the characteristics of the welding temperature field, which instantaneous peak temperature rose to 1808 °C at the local area and attenuated to 600 °C in an elliptic range of about 3.1 cm × 1.7 cm. The failure modes of collar plate reinforced CHS T-joints do not change with preload on the chord and welding thermal. Furthermore, preload on the chord reduces the compressive strength of reinforced joints. The strain distribution and residual deformation are affected by the thermal expansion and cold shrinkage, while the development of the welding temperature field is not affected by the preload. Finally, for compressive strength of CHS T-joints reinforced with collar plate by welding, the applicability of the reduction coefficient due to preload calculated by existing codes was assessed by comparing design values with experimental results. A finite element model by ANSYS, considering the welding heat, was established. Key parameters affecting the strength of the T-joint at the reinforced collar plate under load were identified through parametric study with finite element models. Construction recommendations of welded CHS T-joints are proposed.

Laser Weld Seam Curved Path Effect on 6063 Aluminum Alloy Strength and Temperature Distributions: COMSOL Numerical Simulation

To improve the welding performance of aluminum alloys, a thermal source model of an irregular weld seam was established. COMSOL software was used for numerical simulation of the weld seam geometry effect on the temperature and stress fields in laser welding, which results were experimentally validated. The results show that the ellipsoidal laser welding melted micropool exhibited quasi-steady-state temperature field characteristics. The temperature gradient and thermal stress showed an increase followed by a decline. The temperature fluctuation amplitude of the square-tooth-shaped weld seam exceeded that of the arc-toothshaped one. The temperature evolution of the broken line tooth-shaped weld seam showed a slightly increasing trend, except for the inflection point. The experimental average tensile strength of the weld seam was the highest, reaching about 210 MPa, i.e., roughly 85% of the base material (245 MPa), which coincided with the COMSOL-based temperature field simulation results. With increasing deformation amplitude and transition radius, the maximum tensile force, tensile strength, and elongation at fracture showed an increasing trend. However, the deformation amplitude should be below a certain limit because its increase elongates the welding path and reduces the distance between weld seams, resulting in serious heat accumulation. The tensile fracture morphology of the 6063-T6 base material was curved shear, with shallow toughness pits, small tearing edges at the edges, and small granular objects, indicating small plastic deformation during the fracture process. The tensile fracture of the welded part spanned the weld seam and the base material, and the fracture occurred along the tangent direction of the weld seam. The fracture surface was smooth, the tearing edges at the edge of the toughness pit shifted along the weld seam direction, forming many co-directional slip bands, with highly pronounced plastic deformation.

Numerical study of full penetration single- and double-sided U-rib welding in orthotropic bridge decks

Under the repeated action of residual stress and wheel load caused by welding, fatigue cracks easily occur on the top plate-U rib welding of an orthotropic bridge deck (OBD). These affect the service life. To study the influence of different full-penetration welding methods on the residual stress and fatigue of OBD, this study compared the residual stress, welding deformation, and fatigue performance of full-penetration single- and double-sided welding through finite element analysis. The welding temperature and residual stress fields were simulated based on Goldak's double ellipsoid heat source model using the thermal elastic-plastic method. The numerical results were verified using measured data from relevant literature, and the two were in good agreement. The results showed that the longitudinal residual stress of the double-sided welded U-rib was larger than that of the single-sided welded U-rib, primarily in the compressive stress range, and the maximum deviation reached 99.44 MPa. The longitudinal displacement of single-sided welding along the weld direction was 0.060 mm lesser than that of double-sided welding, and the maximum vertical displacement perpendicular to the weld direction was 2.457 mm lesser than that of double-sided welding. For the same frequency of fatigue load (wheel load), the fatigue strength of single-sided welding was larger than that of double-sided welding, and the fatigue life increased by 29.7%. In this study, analysis models of the full-penetration single-sided and full-penetration double-sided welding were established, which could provide a reference for structural fatigue assessment using the two full-penetration welding techniques under the influence of residual stress.

Temperature Field and Flow Field of Molten Pool in SRA EGW

This study investigates the temperature field and flow field of molten pool in seven-wire rotating arc (SRA) electrogas welding (EGW) with the methods of numerical simulations and experiments. The results show that the welding heat source swings back and forth, and the welding heat source starts to heat from the back of the welding workpiece and gradually swings to the front of the welding workpiece with the swing welding arc. The high temperature area of the molten pool and the sidewall penetration are large due to more heat on the molten pool and the sidewall from the unique rotating force, the large arc heating area, and the non-axial droplet transfer. The isotherm distribution of the molten pool is relatively uniform, and the temperature gradient gradually decreases. The simulated welding morphology is generally consistent with the experimental welding morphology with the same welding parameters, which indicates the correctness of the numerical analysis model of the welding temperature field and flow field.

Study on pulse current auxiliary heating process of submerged arc welding

During the welding process, temperature filed distribution of weldment is one of the key factors which influence welding quality. In order to improve the mechanical properties of welding joint, a technology for heating process of weldment using auxiliary pulse current was proposed in this article. Firstly, through metallographic experiment, strength experiment and hardness experiment, it was proved that the auxiliary pulse current not only can refine grain size but also improves the mechanical property of the welding joint. Then the paper used ANSYS and its ANSYS Parametric Design Language parametric design language to simulate the welding process with assistant pulse current, and the temperature field, the pulse current density distribution and the time of effective pulse current in the welded joint were obtained. Quantitative analyses were undertaken on the influence laws of auxiliary pulse current parameters on weld temperature field, auxiliary pulse current density distribution and the time of effective pulse current. A new parameter was defined as time-current density (the time integral of current density) to demonstrate the change rule of auxiliary pulse current density distribution with time. Finally, analyzing the reasons for raising the welding quality. There were two reasons for such phenomenon: one was auxiliary pulse current change the state of heat distribution in the weld seam area, the other was that the impulse oscillation of the auxiliary pulse influences the nucleation process of melting region.

Analysis and Experiment on the Welding Temperature Field of Multi-Layer and Multi-Pass for RHS–RHS Y-Connections

The temperature measuring instrument was utilized to monitor the welding temperature field at designated points along steel rectangular hollow sections (RHSs) during welding. A total of 32 temperature monitoring points were established on the four surfaces of the RHS branch. Additionally, the welding process was simulated using finite element software to calculate the temperature distribution. The calculated temperature results were then compared with the experimental results obtained from the temperature measuring instrument. The relative errors between the numerical simulation and the experimental temperature results remained within 10%, indicating a reasonable agreement between the two. Once the temperature field was determined, it was used as an input load to calculate the welding residual stress. The longitudinal and transverse residual stresses were analyzed for two paths on the four surfaces of the RHS-to-RHS Y-shaped connection branch. By analyzing the residual stresses, it is possible to evaluate the structural integrity and performance of the welded RHS connection. The analysis process in this paper is crucial for ensuring the safety and reliability of tubular steel structure projects.

Numerical calculation and analysis of temperature field in ultrasonic welding of polypropylene dialyzer

Ultrasonic plastic welding is widely used in the bonding process of medical device accessories. In this paper, a thermo-force indirect coupling finite element analysis model was established in the ultrasonic plastic welding process between the blood cap and the shell of polypropylene (PP) dialyzer. The temperature field distribution between the blood cap and the shell was simulated and analyzed by using finite element analysis software, and the influence of welding process parameters on the temperature field was studied. The results show that: by changing the ultrasonic amplitude parameters, welding time parameters, initial pressure, etc., the longer the ultrasonic welding time, the temperature of the welding area will increase. In order to ensure the quality of the dialyzer, it should be controlled within 0.8-1 seconds. The increase of ultrasonic amplitude will make the welding temperature continue to rise, and in order to avoid poor welding, the amplitude should not exceed 120 ?m. The initial pressure has little effect on the temperature field.

Modeling and measurements of temperature field in the arc welding and hybrid plasma-MAG welding heat source models

Modeling and measurements of temperature field in the arc welding and hybrid plasma-MAG welding heat source models

Numerical analysis of thermal differential distribution in Bobbin tool friction stir welding of 7075-AZ31B dissimilar alloy

The theoretical model of bobbin tool friction stir welding (BT-FSW) structure and dynamic process is established. Because of the great differences in properties of different materials, the mathematical relationship between material stress and deformation will be expressed based on 3D transient heat conduction equation and J-C constitutive model. The BT-FSW process of 7075 and AZ31B was analyzed by finite element method, and the field distribution, thermal cycle curve and stress distribution characteristics of different welding areas of the welded material were simulated. To predict and control the non-equilibrium distribution of welding temperature and stress field, the influences of different Rotating speed, welding speed, offset and other variables on the BT-FSW process of 7075/AZ31B aluminum magnesium dissimilar alloy were studied comprehensively. Finally, the reliability of the model is proved by fitting the experimental and numerical analysis results. The research results show that the temperature of BT-FSW presents an “hourglass” symmetrical distribution, and the stress distribution on both sides of the plate is uniform when the aluminum alloy is placed on the advancing side, the stirring tool is offset to the aluminum alloy by 2mm, and the rotating speed and welding speed are 700r/min and 180mm/min, respectively.

Intelligent Prediction of FSW Physical Quantity and Joint Mechanical Properties

Friction stir welding (FSW) process parameters influence welding temperature field and axial force, which affect welding strength. At present, how the FSW process parameters of aluminum alloy 2219-T8 thick plates influence process physical quantity and how the process physical quantity changes the tensile strength about the welded joint are unknown. We focus on the intelligent prediction of FSW temperature, axial force, and mechanical properties, to provide a basis for FSW process control of aluminum alloy 2219-T8 thick plate. Firstly, we conducted the FSW experiment of aluminum alloy 2219-T8 thick plate. Then, we input the welding process parameters, set up a prediction model by particle swarm optimization-back propagation (PSO-BP) neural network to predict the peak temperature and axial force. Finally, we input the peak temperature and axial force, use genetic algorithm-back propagation (GA-BP) neural network to establish a weld tensile strength estimation model, and comply with the prediction of tensile strength.

Influence of Initial Structural Dimensions of Plates on Welding Distortion

Aiming at the complex full-field deformation problem that easily occurs when welding plates, this paper adopts the elastic–plastic finite element method with heat-force coupling to study the deformation law of plates in different initial states. First, a rectangular plate finite element model with an initial radius and Gaussian heat source model was established to obtain the welding temperature field and deformation field of the plate; then, the method based on digital image correlation technology was used to detect the full-field dynamic deformation of the plate to verify the accuracy of the finite element model; finally, the influence of the initial structural dimensions of the plate on the weld deformation was investigated. The study shows the following: the thermoelastic–plastic finite element model proposed in this paper has high accuracy in both static and dynamic deformation; plates with the same curvature, and different lengths and widths of the initial structure of the plate welding deformation are saddle-shaped, and the edge effect of the welding of the plate is evident, independent of the length of the plate; and the maximum out-of-face deformation of the welding of the plate is linearly related to the length and the closer the aspect ratio of the plate is to 1, the smaller the out-of-face deformation is.

Joining of 304 stainless steel to PET by semiconductor laser conduction welding

304 stainless steel (304SS) and polyethylene terephthalate (PET) were lapped joined by laser conduction welding using a semiconductor laser with a flat-top thermal distribution. Experimental investigation and numerical simulation were conducted to analyze the weld morphology, pores distribution, interfacial microstructure, temperature field, joint strength and fracture behavior of the laser dissimilar joints. Because of the uniform thermal distribution of the laser, the decomposition of the PET base material was well controlled with pore-free joints obtaining at the welding speed over 25 mm/s. Besides, a compound layer was generated at the interface between 304SS and PET with its thickness decreased when the welding speed increased. Chemical reactions and mechanical anchoring were both observed at the interface suggesting a dual joining mechanism. The joint fracture load first increased then decreased with the increased welding speed. Besides, a ductile to brittle failure transition was clearly seen. The underlying mechanism was also discussed.

Study of melt pool dynamics and porosity forming mechanism of laser beam oscillation welding of titanium and aluminum

In this study, a numerical model of oscillation weld butt joint is developed to investigate the welding of titanium alloy with aluminum alloy. Three oscillation paths, namely, straight, sine, and circular, are used to study the distribution of force in the molten pool, the welding temperature field, and the formation and evolution of porosity within the weld. A 3D Gaussian heat source is used to represent the laser beam. The volume of the fluid method is employed to track the gas-liquid free surface, and the gas-liquid interface force is transformed by using the continuous surface force model. The mechanism of keyhole collapse and pore formation was examined along with the fluid flow, surface tension, and recoil pressure on the molten pool. The results confirmed that the highest welding quality is acquired by using a laser welding circular path. Notably, numerical simulation results are validated through experimental data, and circular oscillating laser welding significantly reduced weld seam porosity in the welding of Ti–Al dissimilar alloys. The circular oscillation path with an offset of 0.6 mm and an oscillation amplitude of 0.6 mm is identified as the optimal approach for suppressing pores in the weld joint. This research provides valuable insights into the fundamental mechanisms of keyhole collapse and pore formation in laser welding, which contributes to the advancement of effective welding strategies for dissimilar alloys.

Influence of heat input on temperature and stress field of X80 steel pipeline cirumferential weld using type-B sleeve repairing

Abstract The multi-pass fillet welds of casing pipe were welded onto the in-service pipeline, which is widely used in pipeline repairs. However, the influence of welding heat input of B-type sleeve circumferential fillet weld on the temperature and stress field at the pipe circumferential weld is still unclear. In this paper, a double ellipsoid heat source model is developed to investigate the weld temperature field, residual stress field, and deformation field of the repair welding in service. The results show that the increase of weld heat input can effectively increase the size of the weld pool and the size of the high-temperature zone of the B-type sleeve circumferential fillet weld. And the peak temperature of the inner wall of the pipe girth weld increases with the increase of welding heat input of the sleeve circumferential fillet weld. The axial stress peak of the inner wall of the pipe girth weld reduces with the increase of welding heat input of sleeve circumferential fillet weld, and the axial deformation peak of the inner wall of the pipe girth weld increases first and then decreases with the increase of welding heat input of sleeve circumferential fillet weld.

Temperature field simulation and asymmetric heat transfer distribution of dissimilar steel welded with external transverse magnetic field

During the welding process of Q235 mild steel to 304 L stainless steel, the difference in their thermal properties and magnetic permeability deflects the arc to the mild steel side, resulting in unstable welding process, poor weld formation, and reduced penetration depth. In this paper, a method of applying an external transverse magnetic field acting on the welding arc is proposed to overcome the adverse effects of arc deflection. The experimental results show that the welding depth of Q235/304 L can be significantly improved by magnetically controlled arc welding process. In order to understand the asymmetric heat transfer distribution of dissimilar steel under the action of external transverse magnetic field, a new type of deflection heat source was constructed. The influence of transverse magnetic field deflection arc on heat source parameters was considered, and the welding temperature field of Q235/304 L was simulated to study the welding temperature field of dissimilar steel under the action of magnetic field. In the error analysis, the maximum error of the deflected heat source model is less than 16 %, and the average error is less than 7 %. Compared with the asymmetric heat source model, the constructed heat source model is more accurate in calculation. The depth of melt and temperature variation around the weld under different excitation currents were studied. The weld forming and welding heat transfer law of dissimilar steel with external transverse magnetic field are obtained, which could be used to further improve the welding quality of dissimilar steel.

Numerical Simulation of Layered Bimetallic ZChSnSb8Cu4/Steel TIG-MIG Hybrid Welding Based on Simufact.

Considering the problem of the weak bonding interface structure between the rolling mill oil and film bearing bushings of Babbitt alloy and steel substrate, a numerical simulation of the layered bimetallic ZChSnSb8Cu4/steel by tungsten inert gas (TIG)-metal inert gas (MIG) hybrid welding process was carried out using Simufact Welding software (version 2020). In this study, the TIG-MIG hybrid welding process was simulated to obtain the temperature field and the stress field distributions. The residual stress and the deformation of the weldment were also analyzed using the calculated results. The results showed that the temperature gradient and the thermal stress were reduced in TIG-MIG hybrid welding compared to the conventional MIG welding preparation of layered bimetal ZChSnSb8Cu4/steel, which resulted in an improvement in the structural stability of the weldment. The temperature field and deformation of TIG-MIG hybrid welding of Babbitt alloy were studied under different controlled electrode spacings and TIG welding currents, and it was found that as electrode spacing increased, so did heat loss. Furthermore, with increased TIG welding current, compressive stress increased and tensile stress at the weld decreased, and the maximum thermal efficiency of welding was with a preheating current of 60 A.

Experimental and numerical study on welding temperature field by double-sided submerged arc welding for orthotropic steel deck

Orthotropic steel deck (OSD) is susceptible to fatigue damage when subjected to repeated traffic loads, and the welding residual stress (WRS) is an important factor contributing to fatigue damage in OSD. WRS is formed by the shrinkage of the welds due to the inhomogeneous temperature field during the welds fabrication process, and thus the study of the welding temperature field is of significance for accurately predicting the WRS. As an emerging welding technology, the double-sided submerged arc welding (DSSAW) technology can generate higher welding temperature and consequently higher welding penetration rate on U rib and deck for welding thicker base metal. However, the DSSAW technology generates more complex welding temperature field compared to the traditional arc welding technology, which has not been evaluated so far. In this study, the finite element model (FEM) of OSD with U rib-to-deck (RTD) welded joints is established to simulate the welding temperature field generated by DSSAW. Moreover, the temperature field in OSD by DSSAW is measured by using the infrared thermal imager (ITI) and the industrial temperature measurement gun (TMG) to verify the FEM simulated temperature results. It is found that large surface temperature gradient and large temperature gradient along the thickness direction would be formed at the weld toe of U rib and deck, which is generally the location where the maximum WRS is distributed and where the fatigue cracks are susceptible in OSD. Compared to the inside welding, the outside welding may generate higher welding temperature, higher temperature gradient, and larger molten pool area, resulting in larger WRS in the OSD. The findings in this study can help to an in-depth understanding of the welding temperature field caused by the new DSSAW technology and support further studies on WRS.