Underwater Welding Research Articles

Investigation on dissimilar underwater friction stir lap welding of 6061-T6 aluminum alloy to pure copper

Friction stir welding (classical FSW) is considered to offer advantages over the traditional fusion welding techniques in terms of dissimilar welding. However, some challenges still exist in the dissimilar friction stir lap welding of the aluminum/copper (Al/Cu) metallic couple, among which the formation of the Al–Cu intermetallic compounds is the major problem. In the present research, due to the fact that the formation and growth of the intermetallic are significantly controlled by the thermal history, the underwater friction stir welding (underwater FSW) was employed for fabricating the weld, and the weld obtained by underwater FSW (underwater weld) was analyzed via comparing with the weld obtained under same parameters by classical FSW (classical weld). In order to investigate the effect of the external water on the thermal history, the K-type thermocouple was utilized to measure the weld temperature, and it is found that the water could decrease the peak temperature and shorten the thermal cycle time. The XRD results illustrate that the interface of the welds mainly consist of the Al–Cu intermetallic compounds such as CuAl2 and Cu9Al4 together with some amounts of Al and Cu, and it is also found that the amount of the intermetallic in the underwater weld is obvious less than in the classical weld. The SEM images and the EDS line scan results also illustrate that the Al–Cu diffusion interlayer at the Al–Cu interface of the underwater weld was obviously thinner than that of the classical weld.

Mathematical Model to Predict Heat Flow in Underwater Friction Stud Welding

Friction Stud Welding is primarily used to bond different material. Joining of aluminum alloys, stainless steels and composites with any other materials is required in many underwater welding applications. In the present work, a mathematical model has been developed for underwater friction stud welding. A thick AA6061 plate is welded with steel stud in a modified drilling machine. Transient analysis of heat conduction in the plate has been calculated numerically including heat generation due to friction between the materials. The conduction, convective and surface boundary conditions have been considered as per the developed model. Comparison has been made between welding performed in normal atmospheric condition and underwater condition. The temperature distribution in the work piece has been predicted using the developed mathematical model. It is found that there is steep fall in a heat flow during underwater welding condition. High weld strength can be achieved due to less heat affected zone in underwater welding.

Underwater welding and cutting in CIS countries

Underwater welding and cutting in CIS countries

Investigation of influence of microalloying with titanium and boron of weld metal on its mechanical properties in underwater welding

The Paton Welding Journal, 2014, №06. International Scientific-Technical and Production Journal «The Paton Welding Journal» «The Paton Welding Journal» has been published monthly since 2000 in English, ISSN 0957-798X. «The Paton Welding Journal» is a cover-to-cover English translation of the «Avtomaticheskaya Svarka» (Automatic Welding) journal. The «Avtomaticheskaya Svarka» journal has been published monthly since 1948 in Russian, ISSN 005-111X.

Investigation of composition and structure of weld metal of Kh20N9G2B type made in wet underwater welding

The Paton Welding Journal, 2014, №06. International Scientific-Technical and Production Journal «The Paton Welding Journal» «The Paton Welding Journal» has been published monthly since 2000 in English, ISSN 0957-798X. «The Paton Welding Journal» is a cover-to-cover English translation of the «Avtomaticheskaya Svarka» (Automatic Welding) journal. The «Avtomaticheskaya Svarka» journal has been published monthly since 1948 in Russian, ISSN 005-111X.

Weldability of S500MC Steel in Underwater Conditions

Abstract Wet welding with the use of covered electrodes is one of the methods of underwater welding. This method is the oldest, the most economic and the most versatile. The main difficulties during underwater wet welding are: high cooling rates of the joint, the presence of hydrogen in the arc area and formation of hard martensitic structure in the weld. These phenomena are often accompanied by porosity of welds and large number of spatters, which are more advanced with the increase of water depth. In this paper result of non-destructive tests, hardness tests and metallographic observations of S500MC steel joints performed underwater are presented. The weldability of 500MC steel at water environment was determined

Modeling of underwater wet welding process based on visual and arc sensor

Purpose – The purpose of this paper was to use visual and arc sensors to simultaneously obtain the underwater wet welding information, and a weld seam-forming model was made to predict the weld seam's geometric parameters. It is difficult to obtain a fine welding quality in underwater welding because of the intense disturbances of the water environment. To automatically control the welding quality, the weld seam-forming model should first be established. Thus, the foundation was laid for automatically controlling the underwater welding seam-forming quality. Design/methodology/approach – Visual and arc sensors were used simultaneously to obtain the weld seam image, current and voltage information; then signal algorithms were used to process the information, and the back propagation (BP) neural network was used to model the process. Findings – Experiment results showed that the BP neural network model could precisely predict the weld seam-forming parameters of underwater wet welding. Originality/value – A weld seam-forming model of underwater wet welding process was made; this laid the foundation for establishing a controller for controlling the underwater wet welding process automatically.

Friction taper plug welding for S355 steel in underwater wet conditions: Welding performance, microstructures and mechanical properties

The present work reports new results regarding developing the friction taper plug welding (FTPW) process in wet conditions for underwater welding and repairing solutions. In this study, the FTPW process, microstructures and mechanical properties of the weld are investigated. The main findings are as follows: defect-free FTP welds can be obtained with a 7000rpm rotational speed and an axial force of 30–50kN. In the heat-affected zone (HAZ) and the lower region of the weld metal (WM), a large volume of lath bainite and small amounts of acicular ferrite, polygonal ferrite, and martensite are observed. However, in the upper region of the WM, the microstructure mainly consists of lath martensite. The best results of ultimate tensile strength and V-notch impact energy are 500MPa and 39.5J, respectively, on the joint that was welded with a 45kN axial force. The impact failure is characterised by brittle fracture with a large area of cleavage and notably little quasi-cleavage and ductile.

Hydrothermal flame impingement experiments. Combustion chamber design and impingement temperature profiles

The current work presents the hydrothermal flame impingement experiments conducted for the design of a hydrothermal spallation drilling nozzle. The products of hydrothermal flames of mixtures of ethanol, water and oxygen were injected as free jets in a high pressure water bath. The nozzle design was based on ideas stemming from underwater welding and cutting of metal sheets. Water entrainment in the flame-jets and the heat transfer capabilities of flames injected from various nozzles have been analyzed by measuring their impingement temperature profiles on a flat stainless steel plate. It was found that the thermal-to-kinetic energy ratio of the jet has a direct influence on the entrainment of water in it. Furthermore, the cooling water of the combustion chamber was injected in various angles to the axis of the jet resulting to different entrainment rates. It was found that higher water injection angles reduced the rate of entrainment. Finally, it was indicated that at certain operational points of the jet, its trans-critical properties had an important influence on the impingement temperatures.

Effect of Welding Parameters on Weld Bead Shape for Welds Done Underwater

The desire to model a control system so as to optimize the welding process parameters and the effect of the environment during underwater wet welding makes it necessary to study the effects of these parameters as it affects the weld bead geometry of welds achieved in underwater welding. The objective of this paper is to analyze how welding arc current, voltage, speed, and the effect of the water environment affect the weld bead geometry such as bead width, penetration, and reinforcement height. Comparing the differences of the effects of welding input parameters for air and wet welding as it affects the welding output quality parameter is the method employed in this research paper. The result of this study will give a better understanding of applying control mechanism in predicting the quality of a weld during underwater welding. A clearer insight of the weldability of structural steels for offshore applications as it relates to underwater welding, having a full knowledge of the nonlinear multivariable parameters is indicative of better control methods.

Application Study of Edge Detection for Droplet in Laser Enhanced GMAW Welding

Ambient pressure has a certain inhibiting effect on underwater welding droplet transfer and the stability of welding process. Good droplet transfer of underwater welding plays an important role in improving repairing quality of underwater structures. As an additional droplet separating force, laser provides effective means in improving the welding quality. For quantitative analysis and comparison of laser enhanced effect on droplet transfer, a high-speed camera system to shoot the process of welding droplet transfer was designed and by adopting the frequency domain operation, a filter aiming at image processing of welding droplet was also designed to filter the ambient noise and diffraction fringe. Through edge detection algorithm, edges of droplet images were detected, and the size of droplet was computed accurately with welding wire as the reference. At last, droplets’ statues under different welding parameters were compared. The results show that the clear images of GMAW droplet separated from the noise background can be acquired, which makes the high-precision quantitative analysis of laser enhanced effect possible. All of the results lay a foundation for further test of laser enhanced hyperbaric underwater welding.

Methodology for Measurement of Residual Stress in Welded Joints by the Technique of Pulse-Echo Ultrasound

ABSTRACTRecently they have discovered a large number of oil wells, however these are found in deeper waters. So it is necessary to develop a repair's methodology and inspection for this type of system to prove its operation. This research was focused to establish a methodology for evaluating residual stress generated from the application of solder in a subsea environment, in order to establish whether there is a relationship between residual stress and the depth of the sea. For this purpose was used underwater electrodes (UW -CS- 1) and an API 5L X65 steel to the development of underwater welds, which was welded at 10 and 15 meters depth by a diver welder on site. The measurement of residual stress is developed using non-destructive techniques, the first one was ultrasound technique (UT) which was the technique proposed by viability to being applied in site and as a second option, was applied X-ray diffraction (XRD), with the objective to validate the results obtained by ultrasound technician. The results showed a similar behavior between both non-destructive techniques. In this study was observed the tendency to increase the level of residual stress with increasing the work depth.

A Survey of Underwater Wet Weld Seam Tracking Based on Ultrasonic Sensor

With the exploration of marine sources becoming more and more important, underwater welding is widely needed. Because of the special working condition, underwater weld seam tracking technology is urgently needed, for the automation control of the underwater welding process is the inevitable development trend because of the rigorous environment. This paper used ultrasonic sensor to monitor the weld seam position in underwater wet welding process, and signal process algorithm was developed to obtain the weld seam information, experiment results showed that this method could detect the weld seam shape correctly, this load the foundation for further automatically controlling the welding process.

Prediction of Underwater Wet Weld Seam Forming Based on ARX Model

The exploration of marine resources is becoming more and more important, underwater weld technology is an important technology for the exploration. However, the underwater weld technology is very immature; the underwater weld quality is not as good as the offshore welding. To control and improve the underwater weld quality automatically, arc and visual sensors were used to obtain the information reflecting the weld quality, and ARX (AutoRegressive eXogenous) model was use to model the process, experiment result showed that the prediction results of the model were accurate enough for automatically controlling the process.

Effect of Arc Current Ultrasonic-Frequency Pulsation on Underwater Wet Arc Welding Quality

A novel process of ultrasonic-assisted underwater wet arc welding was proposed to improve the joint properties, a number of ultrasonic-assisted underwater welding experiments were then carried out, and the effects of pulse frequency on weld formation, joint hardness and microstructure were investigated. Experimental results show that the ultrasonic frequency pulsation of arc can improve weld penetration while reducing effectively the hardness of joint HAZ in the arc axial direction and refining the grain of microstructure, and the effects of which are related closely to the pulse frequency.

Active Visual Sensor Based Weld Seam Tracking for Underwater Wet Welding

Weld automation is the development trend of underwater welding, and underwater weld seam tracking is one of the key technologies in weld automation. This paper used active visual sensor to automatically monitor the weld seam in underwater wet weld process, and image processing algorithms were developed to automatically obtain the weld torch deviation, then the weld torch was adjusted automatically according to the deviation obtained by the image, experiment results showed that this method could be used in underwater wet welding.

Numerical Simulation of Underwater Explosive Welding Process

Recently, underwater explosive welding shows its advantage in some difficult-to-weld combinations such as material with thin thickness, high hardness, and fragile quality. The pattern of the typical wave morphology in the interface of the welding specimen indicates the suitability of the selected experimental parameters and sound strength of the laminates. For the existence of the water, traditional Gurney formula and Aziz formula can not directly be used to evaluate the velocity and acceleration process of the flyer plate. Numerical simulation is necessary and irreplaceable for existing knowledge. Underwater explosive welding process was numerically simulated by ANSYS/LS-DYNA to explore the underwater shock wave and deformation process of the flyer plate. Velocity and pressure distribution of welding plates were obtained. The velocity of the flyer plate could satisfy the minimum velocity in explosive welding. It was found that water prevented the gross distortion and ensured the integrity of the composite laminate. Welding rate was increased by expanding the size of the explosive.

Research on Ultrasonic Testing Technology for Polyethylene Pipe Hot-Melting Welded Joints

Due to the advantages of corrosion resistance, no scaling, light weight, polyethylene pipes are widely used in low pressure gas networks and their safety has also been duly noted. As for heat fusion welding of PE pipeline connectors, there is no effective means of detection internally. In this paper, welding specimens were tested under the condition of normal conditions, low melting temperature, low pressure, low heating time melts, underwater welding by the United States imported equipment based on the echo pulse method of ultrasonic testing technology. Comparing with the results of related conditions of tensile tests, this paper found that ultrasound can effectively identify internal defects of hot-melt connectors. And there is a corresponding relationship between the ultrasonic system evaluation grades and the elongation at break, the higher the level, the lower the elongation at break. Related research results can provide the basis for the establishment of PE pipe ultrasonic non-destructive testing inspection standards.

A New Modular Strategy For Action Sequence Automation Using Neural Networks And Hidden Markov Models

In this paper, the authors propose a new hybrid strategy (using artificial neural networks and hidden Markov models) for skill automation. The strategy is based on the concept of using an “adaptive desired” that is introduced in the paper. The authors explain how using an adaptive desired can help a system for which an explicit model is not available or is difficult to obtain to smartly cope with environmental disturbances without requiring explicit rules specification (as with fuzzy systems). At the same time, unlike the currently available hidden Markov-based systems, the system does not merely replay a memorized skill. Instead, it takes into account the current system state as reported by sensors. The authors approach can be considered a bridge between the spirit of conventional automatic control theory and fuzzy/hidden Markov-based thinking. To demonstrate the different aspects of the proposed strategy, the authors discuss its application to underwater welding automation.

Modeling and Analysis of Underwater Wet Weld Process Based on Regression Method

Underwater weld technology is urgently needed for the widely development of marine recourses, and weld automation technology is the inevitable choice because of the underwater environment. Because of the influence of the rigorous environment, the weld seam forming of underwater wet welding is very poor. To control the weld seam forming automatically, the model between the weld parameters and the weld seam shape must be built. This paper used arc sensor to monitor the electrical information of underwater wet welding process, and regression method was used to model the process, and the factors that influence the weld seam forming mostly were analyzed.