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This paper aims to investigate the fabrication of high strength low alloy (HSLA) steels by wire and arc-based directed energy deposition (WADED). Firstly, the relationship between the process variables (including the travel speed-V, the current-C, and the voltage-U) and the geometrical characteristics of weld beads (including the bead height (BH), bead width (BW), and melting pool length (MPL)) was investigated. Secondly, the optimal process variables were identified using the desirability approach. The results indicate that voltage-U has the highest impact on BW and MPL, meanwhile the travel speed-V is the most impacting factor on BH. The optimal variables for the WADED process of HSAL steels are V = 0.3 m/min, C = 160 A, and U = 19 V. The component fabricated with the optimal variables is fully dense without spatters and defects, confirming the efficiency of the WADED process for HSLA steels.

The welding current (A), arc voltage (V) preheating (°C), travel speed (mm·min-1) and net heat input (Qnet) were evaluated, on the strength and morphology of the fracture in experimental HSLA Cr-Ni steel welded joints, with commercial (ERS70S-6) filler metal and robotic GTAW technique. The samples were characterized by uniaxial stress tests, stereoscopy and Digital Image Processing (DIP). The results showed that the resistance to fracture of the experimental steel was exceeded by 18.39% by applying Qnet 0.520 (kJ·mm-1) and the combination of: 200 A, 12.7 V, 25 °C and 180 mm min-1, which influenced the ductile fracture morphology and topology. While the low Qnet (0.200-0.208 kJ·mm-1) favors instantaneous deformation of the welded joints with fracture in the weld bead as the major defect.

The present study deals with the extended version of our previous research work. In this article, for predicting the entire weld bead geometry and engineering stress–strain curve of the cold metal transfer (CMT) weldment, a MATLAB based application window (second version) is developed with certain modifications. In the first version, for predicting the entire weld bead geometry, apart from weld bead characteristics, x and y coordinates (24 from each) of the extracted points are considered. Finally, in the first version, 53 output values (five for weld bead characteristics and 48 for x and y coordinates) are predicted using both multiple regression analysis (MRA) and adaptive neuro fuzzy inference system (ANFIS) technique to get an idea related to the complete weld bead geometry without performing the actual welding process. The obtained weld bead shapes using both the techniques are compared with the experimentally obtained bead shapes. Based on the results obtained from the first version and the knowledge acquired from literature, the complete shape of weld bead obtained using ANFIS is in good agreement with the experimentally obtained weld bead shape. This motivated us to adopt a hybrid technique known as ANFIS (combined artificial neural network and fuzzy features) alone in this paper for predicting the weld bead shape and engineering stress–strain curve of the welded joint. In the present study, an attempt is made to evaluate the accuracy of the prediction when the number of trials is reduced to half and increasing the number of data points from the macrograph to twice. Complete weld bead geometry and the engineering stress–strain curves were predicted against the input welding parameters (welding current and welding speed), fed by the user in the MATLAB application window. Finally, the entire weld bead geometries were predicted by both the first and the second version are compared and validated with the experimentally obtained weld bead shapes. The similar procedure was followed for predicting the engineering stress–strain curve to compare with experimental outcomes.

Selection of suitable parameter range is essential in joining dissimilar combinations joints when more than one number of influencing parameters are present in giving desired output. This paper dis...

Gas metal arc welding process offers higher productivity and good quality weldment as compared to other welding process. The changes in welding process parameters affect the weld bead shape, hardne...

The work presented in this paper deals with the study of the influence of the operating parameters of welding on observables which are the geometrical characteristics of the melted zone. In this study, the method implemented is of the SMAW (Shielded metal arc welding) manual arc type and is used to assemble the pipes through the filling of a V-shaped chamfer between two tubes 1219.5 mm in diameter, 13 mm thick, and a material of grade X70 steel. In order to increase the productivity and reliability of the chamfer filling operation, we used the experimental designs method, on the one hand to estimate the effects of the operating parameters and their interactions on several functions characterizing the morphology of the weld bead, and on the other hand, to provide a mathematical model that links the welding process operating parameters to the objective functions studied.

Welding is one of the ancient manufacturing technologies used for joining of parts. The technology is still applicable to meet various needs of industries, but of course with time-to-time amendments. With the passage of time, numerous scientific investigations has been carried out across the globe on welding technology to keep pace with the modern day requirements. Accordingly, numerous technological modifications and advancements have been suggested & incorporated into almost all the different types of existing welding techniques available, besides developing new techniques also. Metal inert gas (MIG) welding is one such type, which primarily falls under the domain of arc welding. In the present work, bead-on-plate weld beads have been prepared using MIG over austenitic stainless steel specimen (SS-202) using three different types of flux materials and the bead geometry. Results reflected that activated flux material has significant impact over depth of penetration, bead width, weld quality and hardness of welds.

Welding quality detection is a critical link in modern manufacturing, and the weld bead location is a prerequisite for the high-precision assessment of welding quality. It is generally necessary for weld bead detection to be accomplished in the context of complex industrial environments. However, conventional detection and location methods based on specific detection conditions or prior knowledge lack accuracy and adaptability. To precisely detect and locate the weld beads in real industrial environments, a novel weld bead detection and location algorithm is proposed based on deep convolutional neural networks. Because there is no open data set of weld beads and the samples in real industrial applications are insufficient for effective model training of the deep convolutional neural network, a novel data augmentation method based on a deep semantic segmentation network is proposed to increase the sample diversity and enlarge the data set. Then, a dynamic sample updating strategy is put forward to cover more welding situations. Finally, faced with the weak-feature and weak-texture characteristics of weld beads, a simplified YOLOV3 model is proposed to realize end-to-end weld bead location. Experiments demonstrate that the proposed method could effectively satisfy the robustness and precision requirements for weld bead detection and location combined with a deep semantic segmentation network and simplified YOLOV3 model.

Generally, the joining of parts in our industrial life is very important. The industries use joints to increase the length or surfaced area for their requirements and these requirements can be fulfilled generally by joints. Welding is one of the best methods of making joints in which the tungsten inert gas welding is an important method in the welding process. In welding, the beads are formed which are consisted of depth of penetration, weld width and reinforcement height. These dimensions of the beads are the deciding factors of mechanical properties of the weld. In this work, the several experiments were performed with tungsten inert gas welding machine to critically study the effect of welding speed on the dimensions of the bead. All the other input variables except the welding speed were fixed, as the feed rate at 2.12 mm/s, voltage at 9.0 V, welding current at 100 A for whole the experimentation period. Only the values of welding speed were varied and the effect of this variation on depth of penetration, weld width and reinforcement height was investigated. Total six pairs of mild steel plates of dimensions 75 mm × 50 mm × 5 mm were welded for six variations of welding speed. The results were tabulated and were expressed in three different diagrams in which one was for depth of penetration, one was for reinforcement height and one was for weld width. This study explains the sensitivity analysis of the effect of the welding speed on the three dimensions of the weld bead.

In this paper, the effects of the joint type on the driven-out bead of the roll-formed pipes, welded by high-frequency induction welding process are studied. The main goal is to predict and reduce the volume of the bead driven out in the weld seam. Moreover, it aims to move the semi-solid bead during welding to the outer diameter of the pipe. This study has two prior aims: to produce a defect-free joint and to improve the mechanical and metallurgical properties. In order to optimize the weld joint, various joint types have been investigated by experimental tests and simulation. Lastly, destructive tests were used to determine if the desired mechanical properties of the weld joint were obtained. The metallurgical properties and the derivation of the semi-solid material in the weld zone have both been investigated in terms of microstructure. According to the results, the proper joint type improves the mechanical properties by 5% and reduces the volume of the weld bead about 45%.

In this paper, a two-directional automated machine with a controller for flat gas metal arc welding is developed for welding along any complex shape. Consistent and uniform weld bead deposition can...

Advances in the dynamic response of welding power sources have allowed the use of pulsed current at frequencies above 20 kHz. However, the effects of pulsing the welding current at these high-frequency levels are not well known, especially those associated with the voltaic arc. Thus, the aim of this study was to carry out experimental research on a pulsating welding current at ultra-high frequencies focusing on two important voltaic arc parameters in gas tungsten arc welding processes: arc voltage and arc stagnation pressure. The tests were performed with a welding current pulsed at frequencies of 20 to 80 kHz and amplitudes of 0 to 50 A. The results indicated that pulsing the current at ultra-high frequencies leads to a reduction in the average arc voltage, increasing the stagnation pressure and the arc constriction. Regarding the weld bead dimensional aspects, greater values of width and penetration were obtained when the high-frequency current pulsation was applied.

From last decade, Friction Stir Welding (FSW) process finds increasing applications in industry as the process is environment-friendly and offers inherent advantages in mechanical and metallurgical...

Tungsten inert gas welding (TIG) is a widely used fusion welding process to produce a high quality of weld joint for the ferrous and nonferrous alloy with an esthetic weld bead. The limitation of t...

Purpose The modeling and optimization of a weld bead in the middle of the weld are often simple, as the forming process is dynamically balanced. However, the arc striking (AS) and arc extinguishing (AE) areas of weld beads are generally abnormal because the dynamic processes at these areas are unstable. The purpose of this paper is to investigate the abnormal areas of the weld bead with optimization modeling methods in wire and arc additive manufacturing (WAAM). Design/methodology/approach A burning-back method was proposed to fill the slanted plane in the AE area. To optimize the welding parameters and obtain the optimal design, a response surface methodology was proposed to build the relationships between the input parameters and response variables. Findings The proposed burning-back method could fill the slanted plane in the AE area. Second-order models of abnormal areas were developed and the optimization effects were analyzed. The experimental results indicated that the relationship models at both ends were applicable and preferable for the optimization of weld beads. Originality/value In this paper, a burning-back method was proposed to optimize the slanted plane in the AE area. Second-order models of abnormal areas were established. The methods and models were preferable in the optimization of the abnormal areas in WAAM.

The basic purpose of this study was to identify the effect of gas metal arc (GMA) welding process parameters on the weld bead geometry of IS2062 structural steel of A grade. L16 Taguchi orthogonal array (OA) design with the idea of S/N (signal to noise) ratio was applied to obtain objective function to be optimized within the experimental field. In this research work the Taguchi technique was joined with grey relational analysis to solve the multi-response optimization problem. ANOVA (Analysis of Variance) was applied to estimate the most significant input parameters which contribute toward the output parameters. Arc voltage, gas flow rate, and wire feed speed were carefully selected as input parameters, whereas weld bead, depth of penetration, and reinforcement were output respectively. The optimal GMA welding process parameters were identified in order to enhance the productivity and curtail the overall functional cost of weld. Keywords: grey-relational analysis (GRA), Taguchi technique, optimization, GMAW, ANOVA.

The present paper studies the physical properties such as viscosity and grain size of the newly formed submerged arc welding (SAW) fluxes. The response surface methodology (RSM) was applied to formulate the design of experiments (DOE) and fluxes were developed. These properties of developed agglomerated fluxes were used to identify their effect on weld bead appearance and quality of weld. The results were found satisfactory.

Pada kajian ini pengaruh dari arus pengelasan dan kecepatan pengelasan terhadap lebar manik las dan distorsi pada pengelasan gas metal arc welding (GMAW) sambungan tumpul SS 304 telah dilakukan. Bahan yang digunakan dalam kajian ini adalah baja tahan karat tipe 304 (SS 304) dengan konfigurasi sambungan tumpul. Variasi parameter pengelasan GMAW yang digunakan adalah arus pengelasan dan kecepatan pengelasan. Kecepatan pengelasan yang digunakan adalah 115 A, 120 A dan 125 A, sedangkan kecepatan pengelasan yang digunakan adalah 3,6 mm/s, 3,9 mm/s dan 4,2 mm/s. Hasil dari pengelasan akan dianalisis dari lebar manik las dan distorsi yang terjadi. Lebar manik las dan distorsi diukur menggunakan Dino-Lite dan Coordinate Machine Measure (CMM). Metode perpindahan vertikal rata-rata digunakan untuk menghitung distorsi longitudinal bending dan distorsi angular. Hasilnya menunjukkan bahwa menaikan arus pengelasan akan meningkatkan lebar manik las dan distorsi, tetapi jika menaikkan kecepatan pengelasan akan menurunkan lebar manik las dan distorsi. Pada parameter pengelasan 125 A dan 3,6 mm/s menghasilkan lebar manik las atas dan bawah yang terbesar 8,062 mm dan 4,984 mm. Distorsi longitudinal bending dan distorsi angular yang terbesar adalah 1,748 mm dan 4,076 derajat pada parameter pengelasan 125 A dan 3,6 mm/s.

The formation and microstructure of TC4 weld bead was investigated by using pulse ultrasound assisted TIG welding (PU-TIG). The results showed that weld penetration and weld width in the PU-TIG were increased by around 46% and 27%, separately, compared with that of the TIG. The grain sizes in the PU-TIG were smaller than that of the TIG. The minimum grain diameter of 148μm was obtained in the PU-TIG of 10Hz, which was decreased by about 0.5 time compared with that of the TIG. The average hardness of TIG weld seam was about 348HV. In the PU-TIG, the average hardness of the weld seam was about 370HV. Compared with the continuous ultrasonic assisted TIG (U-TIG), ultrasonic efficiency was obviously improved in the PU-TIG.

To gain high cost effective products along with quality and productivity, Pulsed Gas Metal Arc Welding (P-GMAW) process is used in many highly developed industries for fabrication of welded joints. The input parameters are the most important factors which affects the productivity, quality and cost effective for the welding process. The processes enable low net heat input, stable spray transfer and with low mean current. To enhance efficiencies with constant voltage GMAW process, P-GMAW is an outstanding substitute for those industries which are looking to improve quality of welds since the process helps over varying operator’s skills. It is essential to determine the input/output relationship parameters, in order to recognize and control the P-GMAW welding process. P-GMAW applies waveform control logic to fabricate a very precise control of the arc during speed range and a broad wire feed. The power source switches between low background current and a high peak current between 30 to 400 times per second to obtain modified spray transfer process. The peak current pinches off wire droplets and drive it to the welded joints over this period. The process produces low heat input allowing weld pool to solidify, that metal transfer cannot occur but by the mean time, background current maintains the arc with stable spray transfer. Trials have been conducted on SS 304 material using copper coated filler wire of size 1.4 mm based on the Taguchi’s L27 standard orthogonal array. Current, Gas Flow Rate (GFR) and Wire Feed Rate (WFR) with a constant speed are the input parameters considered to carry out trials. The output parameters are Yield strength (YS, N/mm2), percentage of elongation and Ultimate Tensile Strength (UTS, N/mm2). Indirect response parameters are Viz., AE signals such as welding AERMS, welding AEENERGY, tensile AERMS and tensile AEENERGY along with MV signals like area and height of the weld bead are considered to assess the performance of the weld bead joint. It is clearly observed from the obtained results that an excellent relationship exists between welding AERMS welding AEENERGY with tensile AERMS and tensile AEENERGY along with MV signals which were taken at the time of tensile test to evaluate the performance of the weld bead joint. Verification of the results are carried out through performing different NDT testing methods on weld bead joint Viz., X–radiography, Scanning Electron Microscope (SEM) images to analyse external defects in the welded joints. On different zones of welded joint, Energy dispersive analysis (EDX) examination is carried out for elemental composition.

The present study compares the weld performance of the two variants of activated tungsten inert gas welding (A-TIG) process known as, Flux Bonded TIG (FB-TIG) process and Flux Zone TIG (FZ-TIG) process on modified 9Cr–1Mo (P91) Steel. Bead-on-plate welding samples were prepared using TiO2 flux with FB-TIG and TiO2 and ZnO flux combination was used in FZ-TIG process. For systematic comparison, bead-on-plate welding samples were also prepared for A-TIG and conventional, i.e. Normal TIG (N-TIG) process with the same set of process parameters. Metallurgical characterization of all the bead-on-plate weld samples was conducted using optical microscopy, and comparison of weld dimensions was made amongst all the weld samples, prepared understudy. Experimental results showed that the FZ-TIG variant had offered the highest depth of penetration (Dp) and least bead width (Bw) and highest depth-to-width (Dw) ratio, compared to the rest of the variants, which is desirable.

The Shielded Metal Arc Welding (SMAW) is used extensively in different industry segments for different applications, e.g. structural welding, general welding fabrication, etc. Stick electrode is one of the major components of SMAW process. However, end users extensively using these electrodes have reported variable weld penetration and unwanted spattering recurrently during the SMAW process. Concerns have been raised about weld spatter defined as loss of electrode material. Excessive spatter results in productivity loss as unscheduled work stoppage happens due to weld cleanup, repair and rework requirements. Extent of spatter is a major quality issue and a product differentiator. After an elaborate exercise, negligible differences were observed among the electrodes in terms of welding performance issues, e.g. spatter, weld bead profile. Spatter measurement results show that Electrode A produced fewer spatters than Electrodes B and C at almost all current levels. All-weld chemical composition and all-weld tensile properties were also found to be similar for all three electrodes as electrodes were hailed from the same category.

During the production of tube and pipe, a weld bead is developed on inner and outer side of the tube diameter. By electric resistance welding (ERW), the weld bead is very rough and sharp and not favoured for finished tube. Weld bead could be reason for personal injury, loss time accident and product rejection. In this paper, a new kind of cutting tool is developed in which disc spring is introduced and being analyzed numerically using FEA technique. It is found that the force needed to cut the weld bead thickness should be less than the numerical calculated force value.

This work is about the influence rule of inclination of welding torch on the formation and characteristics of weld bead during the pulsed-gas metal arc welding (GMAW) process based on the robotic operation. The inclination of welding torch was an important operation condition during the pulsed-GMAW process, because it can affect the formation and quality of weld bead, which was the output of the process. In this work, the different inclination modes and values were employed to conduct actual welding experiments, and some influence rules can be obtained according to examine the surface topography and cross section. Then, to obtain further rules, serious measurements for the geometry characteristic parameters were conducted and corresponding curve fitting equations between inclination angles and the bead width, penetration and bead height were obtained, and the largest error of these curve fitting equations was 0.117 mm, whose corresponding mean squared error (MSE) was 0.0103. Corresponding verification experiments validated the effectiveness of the curve fittings and showed the second order polynomials were proper, and the largest errors between measurements and curve fitting equations for inclination angle under backward mode were larger than those under forward mode, and were 0.10 mm and 0.15 mm, respectively, which corresponded to the penetration and were below 10%, therefore the equations can be used to predict the geometry of the weld bead. This work can benefit the process and operation optimization of the pulsed-GMAW process, both in the academic researches and actual industrial production.

China low activation martensitic (CLAM) steel is one of the reduced activation ferritic/martensitic (RAFM) steels that have been widely considered to be the candidate structural materials for the n...

Fatigue cracking in steel girder web penetration details is so dangerous that it can break steel girders completely. In 2006, one-meter-long crack was detected in Yamazoe Bridge. Since a number of highway bridges have such web penetration details in Japan, it is of urgent importance to grasp these fatigue strength properties and develop effective retrofitting methods. In previous studies, we investigated fatigue cracking behavior through fatigue tests using small girder specimens with web penetration details and effects of large attachment retrofitting methods against fatigue cracking in web penetration details through fatigue tests using a large girder specimen with web penetration details in which cross beam lower flanges are connected to lower surface of a slot by welding. However these methods cannot prevent fatigue crack initiation perfectly. In this study, we investigate effects of weld bead removal and small angle steel attachment retrofitting method against fatigue cracking in web penetration details through fatigue tests using a large girder specimen. As a result, it has been verified that weld bead removal and small angle steel attachment method can prevent fatigue crack initiation perfectly in the web penetration details with a slot.

A difficult task for the transport sector is to make its assemblies lighter and perform more efficiently. Use of aluminum and its alloys has increased extensively in this sector because of reduction in weight of the vehicles and resulting energy savings. High thermal conductivity and thermal expansion pose difficulty in welding of these alloys. Cold metal transfer (CMT), a low heat input welding process, is the best choice for welding of these alloys. However, controlling the welding input parameters is highly necessary to obtain defect-free and high strength welded joints. In the present study, an attempt is made to develop a Matlab software-based application by two approaches, such as multiple regression analysis (MRA) and adaptive neuro-fuzzy inference system (ANFIS), for predicting the complete weld bead shape (graphical representation) of AA5052 using the CMT welding process. The data inputs used for both approaches are welding current (A) and welding speed (mm/min), respectively. A graphical interface is built to help the user to choose welding input parameters and obtain directly a representation of the weld bead profile in graphical form. In addition, the output response shows the complete weld bead shape, which is defined by the X and Y coordinates of the various points in the weld bead profile. The results are validated with randomized tests against the weld bead shape predicted by Matlab. Comparatively, ANFIS is the more effective method for predicting the weld bead profile and shows better agreement with the experimental profile than MRA. Further, the reliability and stability of the ANFIS model were determined from the mean absolute error percentage, root mean square error values, and linear R2fit model, confirming that the ANFIS-based prediction is in better agreement with the experimental values than MRA.

High-power double-wire gas metal arc welding (GMAW) experiments were conducted with the single and double pulses technology. The effects of single and double pulses on the weld bead formation, microstructure and mechanical properties of the weld joints were investigated. The experimental results demonstrated that through the high-power double-wire single and double pulsed GMAW stable welding could be achieved. Also, the high quality weld beads were acquired with slight spatter, without undercut or hump. Double-wire double pulsed GMAW was more stable, producing more perfect weld shape and higher microhardness compared to double-wire single pulsed GMAW. The stirring effect of alternating strong and weak pulses on the weld pool during the double-wire double pulsed GMAW could produce significant fish-scale ripples and refine the grains, resulting in finer grain microstructure with higher hardness. The results proved that the low-frequency pulse cycle controlled the formation of each weld pool precisely. This meant that a weld pool was formed in a low-frequency pulse cycle.

In this paper, a new (novel) welding technology has been applied to join 0.1 mm thin plates. An initial study on the influence of welding current on the welding properties for stainless steel SUS304 plates is discussed in this paper. The weld bead appearance on both top surface and bottom surface was observed by microscope to indicate the change of weld bead size and welding defects. The results showed that by utilizing a constricted nozzle, a good weld bead is found out when the arc length is too short (0.3 mm), welding speed is very high (3000 mm min-1) and base metal is very thin (0.1 mm) with suitable welding conditions.

Metals created by melting basic metal and welding rods in welding operations are referred to as weld beads. The weld bead shape allows the observation of pores and defects such as cracks in the weld zone. Radiographic testing images are used to determine the quality of the weld zone. The extraction of only the weld bead to determine the generative pattern of the bead can help efficiently locate defects in the weld zone. However, manual extraction of the weld bead from weld images is not time and cost-effective. Efficient and rapid welding quality inspection can be conducted by automating weld bead extraction through deep learning. As a result, objectivity can be secured in the quality inspection and determination of the weld zone in the shipbuilding and offshore plant industry. This study presents a method for detecting the weld bead shape and location from the weld zone image using image preprocessing and deep learning models, and extracting the weld bead through image post-processing. In addition, to diversify the data and improve the deep learning performance, data augmentation was performed to artificially expand the image data. Contrast limited adaptive histogram equalization (CLAHE) is used as an image preprocessing method, and the bead is extracted using U-Net, a pixel-based deep learning model. Consequently, the mean intersection over union (mIoU) values are found to be 90.58% and 85.44% in the train and test experiments, respectively. Successful extraction of the bead from the radiographic testing image through post-processing is achieved.

Laser welding is widely used for its advantages like deeper weld penetration, narrow heat affected zone, higher welding speeds and better weld quality with less damage to the workpiece compared to arc welding processes. The purpose of this paper is to determine the influence of major laser welding process parameters of beam pulse energy, travel speed and focal position on weld fusion zone geometry in stainless steel and optimizing these parameters to obtain maximum penetration and minimum weld width simultaneously. The experiments were planned according to Taguchi’s L16 orthogonal array. The grey-based Taguchi method was then employed to convert the multiple quality criteria into one single relational grade. Based on the calculated relational grade, Taguchi tools such as analysis of variance and signal-to-noise ratio were used to analyze and obtain the significant parameters and evaluate the optimum combination levels of the mentioned process parameters. Moreover, the effect of optimization procedure was studied on the microstructure and micro-hardness of the weldments. It was concluded that this optimization method can lead to elimination of chain ferrite precipitation and more uniform micro-hardness across the weld bead. The confirmation experiments verified that this method can effectively improve multiple performance characteristics and the results are reproducible in laser welding.

In the present study, the influence of concave geometry shoulder tool of FSW on weld quality was analysed by using Acoustic Emission and Image processing techniques has been done. The interaction of tool shoulder with base material in the arrangement of friction stir weld is studied by contemplated the banded texture of weld bead surface using image processing techniques. Experiments are carried out by capturing the images of weld bead surface of friction stir welded specimens produced using different process parameters. The images are digitally processed and analysed by characterizing locale of interest along good and defect weld region based on X-Ray radiography and AE results of friction stir welded specimens to determine first order and second order measurable statistical textural parameters of weld bead surface using MATLAB

Over past decades manufacturing processes have gained utmost importance in various industrial applications. Welding is one such manufacturing process. Various types of welding processes such as Metal inert gas welding (MIG), submerged arc welding (SAW), Tungsten inert gas welding (TIG) etc. are in frequent use. The present investigation is directed to study the effect of process parameters on hardness of weldment by combining Metal inert gas welding (MIG) and submerged arc welding (SAW). Both the processes are performed subsequently one after the other on heavy duty mild steel. The results show lower hardness values compared to only SAW.

S304HCu stainless steel is inevitable materials in super heater and reheater tubes in steam power boiler industries. The major challenge in welding of T92 steel and S304HCu stainless steel is the selection of the appropriate filler wire and establishing welding procedures especially in dissimilar welding such that the weld joints meet the service requirements at high temperatures. This present work is aimed to study the effect of welding current and wire feed rate on weld bead geometry produced with hot wire gas tungsten arc welding (HW-GTAW) process using different filler wires of 0.8mm diameter viz., ERNiCrFe-7A (IN 52M) and ERNiCrCoMo-1 (IN 617) on S304HCu stainless steel tubes. These weld bead depositions were made at hot wire current of 30A with two different welding currents viz., 130A and 110A at a constant wire feed rate and travel speed. From the results, it is established that temperature distribution and the presence of surface active elements are the causes for the formation of weld beads in different shapes.

Austenitic stainless steel (ASS) is widely fabricated by tungsten inert gas (TIG) welding for aesthetic look and superior mechanical properties while compared to other arc welding process. Hitherto, the limitation of this process is low depth of penetration and less productivity. To overcome this problem activated tungsten inert gas (A-TIG) welding process is employed as an alternative. In this investigation the welding performance of conventional TIG welding is compared with A-TIG process using TiO2and SiO2flux with respect to weld bead geometry. The experimental investigation on A-TIG welding of ASS-201 grade shows TiO2flux helps in achieve higher penetration as compared to SiO2flux. While welding with SiO2the hardness in HAZ and weld region higher than that of TIG welding process.

The weld bead formation process is closely related to welding materials because of the thermophysical properties involved. In this paper, a 3D numerical calculation model to explore the weld bead formation process in fiber laser welding of dissimilar materials is presented. The formed welded joint during the fiber laser welding of dissimilar materials shows characteristics that are different from that during the welding of the same material. The differences in the thermophysical properties between the materials are taken into consideration in the developed model. By means of comparison with the laser welding of the same material, the corresponding formation characteristics of a dissimilar weld bead are analyzed in terms of temperature distribution, molten metal flow, and thermophysical properties based on numerical simulation results. Due to the differences in the thermophysical properties, the weld bead, the temperature field, and the flow field are asymmetric in the laser welding of dissimilar materials. The moving processes of the two sides of the molten pool are extracted and discussed. The influence of an asymmetrical flow field on both sides of the molten pool is the critical factor accounting for the generation of asymmetric behaviors in the dissimilar material fiber laser welding. The proposed method in this paper can be utilized to provide guidance for revealing the weld formation process in dissimilar laser welding and to obtain weldment with high quality in practical welding.

High productivity, excellent joint strength and small weld bead make friction stir welding an emerging joining technique to join difficult to weld dissimilar aluminum alloys. Effect of rotational speed, traverse speed and shoulder diameter on the joint strength and elongation of the friction stir welded dissimilar aluminum alloys (AA7475-AA2219) is investigated. In addition, parameters are optimized to obtain joint with narrow weld bead and high joint efficiency using the entropy-weighted technique for order of preference by similarity to ideal solution method. Nine experiments are performed as per the L9 orthogonal array and mechanical properties of the welded joints are measured. Results of the study reveal that optimum values of ultimate tensile strength and percentage elongation are obtained at a rotational speed of 710 rev/min, welding speed of 250 mm/min and shoulder diameter of 10 mm resulting in good joint strength, high productivity and narrow weld bead. From the selected process parameter range, tool shoulder diameter is found to be the most significant parameter. The findings of the present study are discussed in light of the friction stir welding process mechanism, available literature, mechanical testing, microstructure and fractography.

Selecting suitable welding process parameters to obtain optimal mechanical properties of the weld bead in AC gas tungsten arc welding is of vital importance. This paper presents a combination method of the Kriging model and particle swarm optimization for optimizing welding process parameters to achieve the optimum mechanical properties, such as the tensile strength and micro-hardness, of the weld bead in AC gas tungsten arc welding of GW53 magnesium alloy plates. The Taguchi orthogonal array is first employed to construct a database including the input process parameters (welding speed, welding current, and protection gas flow) and the responses (the tensile strength and micro-hardness of the weld joint). Then, the Kriging model is used to establish the relationships between the input process parameters and the responses. The optimal mechanical properties of the weld bead corresponding to the welding process parameters are obtained by the proposed hybrid Kriging and particle swarm optimization algorithm. Finally, the effectiveness of the proposed method is verified by contrasting the mechanical properties, such as the tensile strength and the average micro-hardness, in the welding base metal and the weld bead. Furthermore, the main reasons for the decrease in the mechanical properties of welded plates are described in this paper.

The effects of shielding gas composition on wire melting rate, deposition efficiency, and geometry of the welds were studied. Commercial shielding gases were evaluated, among them pure Ar, pure CO 2 , Ar + CO 2 mixtures and Ar + 5% H 2 . The Ar + 8% CO 2 mixture exhibited superior deposition efficiency and weld bead wettability. In contrast, the wire melting rate obtained with Ar + 5% H 2 mixture was significantly higher than all other tested gases. In order to simultaneously obtain the advantageous characteristics produced by the CO 2 and H 2 additions, further tests were performed with ternary mixtures consisting of Ar + 5% H 2 with various CO 2 contents. The best results were obtained with Ar + 5% H 2 + 7% CO 2 mixture, which yielded an increase in wire melting rate with deposition efficiency and weld bead wettability similar to those of the Ar + 8% CO 2 .

The TIG process with hot-wire addition is described as a highly productive process in comparison with conventional TIG process with cold-wire and achieves large deposition rates and low dil...