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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.

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.

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.

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.

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.

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 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.

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 surface texture of friction stir weld is related to internal structure of weld. The statistical image parameters along good and defect weld regions are quantitatively evaluated for quality from the weld bead images, which are processed and analyzed using machine vision technique and X-ray radiography. The weld strength obtained along the weld regions showing similar variations in Acoustic Emission (AE) data, which was acquired during welding and image data of the weld bead are analyzed to assess the weld quality. The combined model developed using limiting values of image data and AE data along different regions of weld evaluate the weld quality more reliably.

The radiographic test used to inspect the internal defects is an important non-destructive testing technique for welding. The weld bead radiographs of different detection scenes and different types of defects are very different, which limits the versatility of the automatic detection algorithm. This paper solves this problem by analyzing the radiographic images at different scales and intensities. Firstly, a multi-scale multi-intensity parameter space is established, and the preprocessed images corresponding to the parameters ensure that defects are not missed. Then, through the detection standard of the weld and the properties of the radiographic image, the value range of the parameters is automatically limited and the preprocessed image is optimized. Finally, algorithms for screening and merging defects in different preprocessed images are designed to reduce false detections and describe precise defect boundaries. Experimental results show that the algorithm proposed in this paper is universal, robust and accurate.

LONGLIFE (“Treatment of long term irradiation embrittlement effects in RPV safety assessment”) was a collaborative project of the 7th Framework Programme of EURATOM under the umbrella of NULIFE/NUGENIA, aiming at an improved understanding of irradiation effects in reactor pressure vessel steels under conditions representative of long term operation. The LONGLIFE project was completed by the end of January 2014. The paper gives an overview of the main project results and their implications for future research, as discussed at the final project workshop. The microstructural database for neutron-irradiated RPV steels was extended considerably and existing gaps on mechanical property data were closed. Indications of late blooming effects (LBE) were found in some cases, but clear criteria for the occurrence/exclusion in terms of irradiation conditions and chemical composition have still to be developed. The commonly accepted trend, that low flux and low irradiation temperature promotes LBE, is supported. A significant flux effect on the size of defect clusters was observed in two high Cu weld materials, while the changes of mechanical properties are not affected by the neutron flux. The database requires completion in particular for low-Cu RPV steels. The shift of reference temperature T 0 over the thickness location of a VVER-440 welding seam does not follow the prediction Russian code, because of the strong variation of the intrinsic weld bead structure. Therefore, the effect of the initial microstructure and of the heterogeneity on the radiation behaviour has to be addressed in future works. Existing embrittlement trend curves models were applied to the LONGLIFE data base. None of the trend curves could predict the behaviour of the entirety of the LONGLIFE materials sufficiently. A guideline for monitoring radiation embrittlement during life extension periods was developed.

Arc sound signals contain abundant information about the welding process, so they are widely adopted to monitor the penetration states of weld bead online. However, the arc sounds are vulnerable to back ground noises, which limits the practical application of them in industry. In this study, a central auditory perception model was proposed. This model through simulating human auditory system to identify the penetration states of weld bead in GMAW process. Firstly, the auditory spectrums of the arc sounds are obtained through auditory peripheral model. Then the shape of auditory spectrums is analyzed by an auditory cortex model. Finally, according to the auditory cortical response, character vectors are built and used to identify the penetration states. The results show that the proposed method has a high accuracy rate in the identification of penetration states of weld bead. This research provides a new method for the online monitoring of welding quality.

The aim of this paper is to present a new numerical heat source for gas tungsten arc welding (GTAW) simulation. This source is described as a homogeneous thermal flux which is defined by a power P distributed in a disk the radius of which is R : it enables the main dimensions of the weld bead and the evolution in temperature in the solid part to be predicted. The two parameters P and R relate to the process parameters, the arc length h and the current intensity I . Experimental tests were performed in order to study the weld bead dimensions in incomplete penetration and full penetration welds. For each test, the heat source parameters ( P , R ) which enable the experimental weld bead dimensions to be obtained were identified: a link between the heat source parameters ( P , R ) and the welding parameters ( I , h ) was established and thus a predictive heat source was produced.

Modern and expensive parts lead to an increasing demand for maintenance, repair and overhaul (MRO) technologies. Instead of part replacement, MRO technologies are economically advantageous throughout the life cycle. Laser metal deposition as modern MRO technology can be used to repair cracks or protect damaged surfaces with a hard facing layer. It is necessary to adjust weld bead profile to the specific task. For this purpose, Design of Experiment (DoE) has a high potential to decrease experimental effort. In this paper, a full factorial design is used to determine the effect of process parameters on the geometric dimensions of the weld bead. The paper is of interest to engineers working with laser metal deposition as well as DoE methods.

An important issue in current fusion materials research is finalizing the detailed manufacturing specification for ITER test blanket modules. The objective of this study is to clarify Ta effects of the hot cracking susceptibility of welds in F82H steels with controlled Ta contents up to 0.14%. Hot cracking susceptibility was evaluated with transverse-Varestraint testing. Hot cracks that occurred in the weld bead during the test were mainly solidification cracks. Maximum length slightly increased with increased Ta content. On the basis of the brittleness temperature range (BTR), evaluated by measuring maximum crack length and welding thermal cycle the BTR was slightly wider due to the increase in Ta content. However, the value of the temperature ranges was about 10 K. The hot cracking susceptibility of F82H steel was the same or better than commercial steels.

The aim of this work is to evaluate the reliability of non-destructive test (NDT) techniques for the inspection of pipeline welds employed in the petroleum industry. Radiography, manual and automatic ultrasonic techniques using pulse-echo and time of flight diffraction (TOFD) were employed. Three classes of defects were analyzed: lack of penetration (LP), lack of fusion (LF) and undercut (UC). The tests were carried out on specimen made from pipelines containing defects, which had been artificially inserted on laying the weld bead. The results showed the superiority of the automatic ultrasonic tests for defect detection compared with the manual ultrasonic and radiographic tests. Additionally, artificial neural networks (ANN) were used in the detection and automatic classification of the defects.

The objective of this study is to validate a finite element analysis (FEA) simulation methodology to predict the global behavior of thin-walled elbows subjected to in-plane bending. Two in-plane closing mode bending tests and one in-plane opening mode bending test were conducted on 2″ schedule 10 elbows, and a nonlinear FEA procedure was used to simulate the tests. A detailed FEA study was carried out to determine the relative importance of weld size and location, measured wall thicknesses, and original cross-section dimensions on the reconciliation results. When the weld bead was included in the analysis, the reconciliation results for load–displacement behavior and some of the strain measurements were excellent. For those cases in which the strain measurements reconciliations were not so good, a possible explanation is provided.

The effect of controllable process variables on the heat input and the area of the heat-affected zone (HAZ) for bead-on-plate and bead-on-joint welding were calculated and analyzed using mathematical models developed for the submerged arc welding of pipes (SAW). A comparative study of the area of the heat-effected zone between bead-on-plate and bead-on-joint welding was carried out. This comparative study reveals that the models developed for bead-on-plate for predicting weld bead qualities need further modification before applying to the actual joining of metals by welding. It is found that the area of the HAZ is greater for bead-on-plate than that for bead-on-joint and that the effects of SAW process variables on the area of the HAZ on plate is as same as that of the area of the HAZ on joint, and follows the same trend.

In order to investigate the difference in the behavior of bubbles between in a microgravity environment and in a terrestrial environment, gas tungsten arc (GTA) welding was performed in both environments. The microgravity environment was produced for 10 seconds with less than 10−5 G with a drop-shaft type system at the Japan Microgravity Center (JAMIC). The materials used were an aluminum alloy and pure silver. It has become clear that more pores are left in the weld in the microgravity environment than in the terrestrial environment. The bubbles cannot easily be released from the weld pool before solidification due to the lack of buoyancy in the microgravity environment. In the microgravity environment, blowholes are distributed uniformly in the weld and are smaller than those in a terrestrial environment. In the microgravity environment, the weld bead is formed flatly though the weld shape is significantly affected by gravity in the terrestrial environment. This indicates that in the microgravity environment, a larger amount of metal can be welded at once and in any welding position.

Dynamic crack initiation in BS 4360 50B steel specimens has been achieved by testing the steel with a brittle superimposed Hardex 450 weld bead. The effect of this brittle weld has been shown to move the ductile-brittle transition temperature for the underlying steel from conventional values of approximately −60°C to higher values of the order of −35 to −40°C. The extent by which the transition temperature is raised is shown to be dependent upon the stored energy present in the tested structure. The results confirm that the problem of arresting a running crack in structural steels is not solely a property of the material under test but depends upon the total strain energy stored in the system.