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The purpose of this paper is an experimental investigation to determine the effects of defects on the strength of welds.

This investigation was carried out using butt- and fillet-welded specimens in tension. Several welding skills were incorporated into the investigation so as to come up with different types of defects. Half of the samples were welded flat and the other half, vertical.

Vertical welding resulted in a greater percentage of defects than flat welding. Most of the defects in the welds were a result of incomplete penetration, lack of fusion, slag inclusion, porosity and failure to weld to the given dimensions. The tests show that there is a linear relationship between the area of defects and the ultimate capacity of the joints.

Although the purpose of this research was to determine the effect of defects on the strengths of both butt and fillet welds, more attention was focused on fillet welds, as this investigation had not been carried out before. Fillet welds experience shear only, unlike butt welds which can either be in tension or shear, or, in rare cases, a combination of the two.

This work demonstrates the development of a robot, which was designed for the orbital welding of pipes.

The robot consists of a small car pressed against the pipe by means of chains, which are used by the robot to move around it. To provide all necessary torch movements, the robot must have four degrees of freedom: torch travel speed, stick‐out, torch angle and lateral motion. Thus, using a look‐up table‐which was specially designed to this application‐it is possible to follow the optimal parameters (voltage, current, welding speed, torch angle and stick‐out) for each welding position (flat, vertical and overhead).

The robotization of the orbital welding process brings enhancement in the final product quality, considerable increase of repeatability, reduction of rework and reduction of the weld execution time. At the very least, the robot is capable to reproduce the weld bead of the best human welder, through the use of the same paramenters contained in a table.

The use of this robot in welding with GMAW proved to be extremely viable. It was shown that the bead shape did not suffer great variations from one welding postion to another, thanks to the use of a gradual change of parameters.

Although, by RIA definition the devices for the orbital welding shown in literature up to now are not robots, the developed device can be called a robot due to its capability of being completely programmable and automatically carrying through all welding activities.

Recognition and guidance of initial welding position (IWP) is one of the most important steps of automatic welding process, also a key technology of autonomous welding process. The purpose of this paper is to advance an improved Harris Algorithm and grey scale scanning method (GSCM) to raise the precision of image processing.

Through the configuration of “single camera and double positions,” a new set of image processing algorithms is adopted to extract feature points by using the pattern of rough location and subtle extraction, so as to restructure three‐dimensional information to guide robot move to IWP in the practical welding environment.

Experiments showed that mean square errors (MSEs) in X, Y, Z‐directions for both flat butt joint and flat flange are 0.4491, 0.8178, 1.4797, and 0.5398, 0.4861, 1.1071 mm, respectively.

It has a limitation in providing guidance for only one step, and would be more accurate if fractional steps are adopted.

Guidance experiments of IWPs on oxidant tank's simulating parts are carried out, whose success rate is up to 95 percent and MSEs are 0.7407, 0.7971, and 1.3429 mm. It meets the demands of continuous and automatic welding process.

Improved Harris Algorithm and GSCM are advanced to raise the precision of image processing which influenced guidance precision most.

The purpose of this paper is to compile a comprehensive status report on pipes/piping networks across different industrial sectors, along with specifications of materials and sizes, and showcase welding avenues. It further extends to highlight the promising friction stir welding as a single solid-state pipe welding procedure. This paper will enable all piping, welding and friction stir welding stakeholders to identify scope for their engagement in a single window.

The paper is a review paper, and it is mainly structured around sections on materials, sizes and standards for pipes in different sectors and the current welding practice for joining pipe and pipe connections; on the process and principle of friction stir welding (FSW) for pipes; identification of main welding process parameters for the FSW of pipes; effects of process parameters; and a well-carved-out concluding summary.

A well-carved-out concluding summary of extracts from thoroughly studied research is presented in a structured way in which the avenues for the engagement of FSW are identified.

The implications of the research are far-reaching. The FSW is currently expanding very fast in the welding of flat surfaces and has evolved into a vast number of variants because of its advantages and versatility. The application of FSW is coming up late but catching up fast, and as a late starter, the outcomes of such a review paper may support stake holders to expand the application of this process from pipe welding to pipe manufacturing, cladding and other high-end applications. Because the process is inherently inclined towards automation, its throughput rate is high and it does not need any consumables, the ultimate benefit can be passed on to the industry in terms of financial gains.

To the best of the authors’ knowledge, this is the only review exclusively for the friction stir welding of pipes with a well-organized piping specification detailed about industrial sectors. The current pipe welding practice in each sector has been presented, and the avenues for engaging FSW have been highlighted. The FSW pipe process parameters are characteristically distinguished from the conventional FSW, and the effects of the process parameters have been presented. The summary is concise yet comprehensive and organized in a structured manner.

Examines the development of a new high speed rotating arc welding system. Describes the rotation mechanism and looks at the characteristics and phenomena of this welding method. Discusses the principles and performance of the arc sensor. Concludes that a six‐axis vertical multiple joints arc welding robot has been developed to meet the increasing high standards required of arc welding robots.

Aims to present missing knowledge of welding and sensor application with rotating torch to the technically and economically meaningful employment. With the help of this knowledge, on the one hand, the potential user is to be informed about the applicability of the system in the context of his production line and his products and on the other hand, the classification of the system in the range of the alternatives available on market.

Introduces the welding operation and experimental results of rotating torch integrated with a sensor device using a 6‐axis robot. Performed various laboratory experiments investigating variable frequency values with different torch orientations.

Figures out the optimum frequency and torch orientation to obtain ultimate welding geometry by means of compensating gaps with increased weld root. Observed the possibility of out‐of‐position welding.

In this manner, provides a great scope as a pioneer application in industry and a guidance for forthcoming researches.

Allows welding of thin sheet metals.

Presents a seminal concept in the field of any industrial applications such as marine and pipeline construction.

This paper aims to present a friction stir molding (FSM) method for the rapid manufacturing of metal tooling. The method uses additive and subtractive techniques to sequentially friction stir bond and then mill slabs of metal. Mold tooling is grown in a bottom-up fashion, overcoming machining accessibility problems typically associated with deep cavity tooling.

To test the feasibility of FSM in building functional molds, a layer addition procedure that combines friction stir spot welding (FSSW) with an initial glue application and clamping for slabs of AA6061-T651 was investigated. Additionally, FSSW parameters and the mechanical behavior of test mold materials, including shear strength and hardness, were studied. Further, scanning electron microscopy (SEM)/elemental map analysis (EDS) of the spot weld zones was carried out to understand the effect of FSSW on the glue materials and to study potential mixing of glue with the plate materials in the welded zone.

The results indicate that FSM provides good layer stacking without gaps when slabs are pre-processed through sand blasting, moistening, uniform clamping and FSSW using a tapered pin tool. The tensile shear strength results revealed that the welded spots were able to withstand cutting forces during machining stages; however, FSSW was found to cause hardness reduction among spot zones because of over-aging. The SEM/EDS results showed that glue was not mixed with slab materials in spot zones. The proposed process was able to build a test tooling sample successfully using AA6061-T651 plates welded and machined on a three-axis computer numerical control (CNC) mill.

The proposed FSM process is a new process presented by the authors, developed for the rapid manufacturing of metal tooling. The method uses additive and subtractive techniques to sequentially friction stir bond and then mill slabs of metal. The use of FSSW process for materials addition is an original contribution that enables automatic process planning for this new process.

The purpose of this paper is to quantitatively investigate the effect of process parameters (including welding current, voltage and speed) and plate thickness on in-plane inherent deformations in typical fillet welded joint; meanwhile, the plastic strains remaining in the weld zone are also analyzed under different influencing factors.

To achieve the purpose of this study, a thermal-elastic-plastic finite element (TEP FE) model is developed to analyze the thermal-mechanical behavior of the T-welded joint during the welding process. Experimental measurements have verified the validity of the established TEP FE model. Using the effective model, a series of numerical experiments are performed to obtain the inherent deformations under the conditions of different influencing factors, and then the calculation results are discussed based on the relevant data obtained.

Through numerical simulation analysis, it is found that the longitudinal and transverse inherent deformations decrease with the increase of welding speed and plate thickness, whereas as the nominal heat input increases, the inherent deformations increase significantly. The longitudinal shrinkage presents a quasi-linear and nonlinear distribution in the middle and end of the weld, respectively. The plastic strains in the cross section of the T-joint also vary greatly because of the process parameters and plate thickness, but the maximum value always appears near the location of the welding toe, which means that this point faces a relatively large risk of fatigue cracking. The inherent deformations are closely related to the plastic strains remaining in the weld zone and are also affected by many influencing factors such as process parameters and plate thickness.

In this study, relatively few influencing factors such as welding current, voltage, speed and plate thickness are considered to analyze the inherent deformations in the T-welded joint. Also, these influencing factors are all within a certain range of parameters, which shows that only limited applicability can be provided. In addition, only in-plane inherent deformations are considered in this study, without considering the other two out-of-plane components of inherent deformations.

This study can help to expand the understanding of the relationship between the inherent deformations and its influencing factors for a specific form of the welded joint, and can also provide basic data to supplement the inherent deformation database, thereby facilitating further researches on welding deformations for stiffened-panel structures in shipbuilding or steel bridges.

The study aims to fabricate large metal components with overhangs built on cylindrical or conical surfaces with a high dimensional precision. It proposes methods to address the problems of generating tool-paths on cylindrical or conical surfaces simply and precisely, and planning the welding process on these developable surfaces.

The paper presents the algorithm of tool-paths planning on conical surfaces using a parametric slicing equation and a spatial mapping method and deduces the algorithm of five-axis transformation by addressing the rotating question of two sequential points. The welding process is investigated with a regression fitting model on a flat surface, and experimented on a conical surface, which can be flattened onto a flat surface.

The paper provides slicing and path-mapping expressions for cylindrical and conical surfaces and a curvature-speed-width (CSW) model for wire and arc additive manufacturing to improve the surface appearances. The path-planning method and CSW model can be applied in the five-axis fabrication of the prototype of an underwater thruster. The CSW model has a confidence coefficient of 98.02% and root mean squared error of 0.2777 mm. The reverse measuring of the finished blades shows the residual deformation: an average positive deformation of about 0.5546 mm on one side of the blades and an average negative deformation of about −0.4718 mm on the other side.

Because of the chosen research approach, the research results may lack generalizability for the fabrication based on arbitrary surfaces.

This paper presented an integrated slicing, tool-path planning and welding process planning method for five-axis wire and arc additive manufacturing.

A structural element of an aeroplane comprises a sheath of thin sheet metal and a wooden core fitting closely within and completely filling the sheath, the core being held under endwise compression by means of metal discs or plugs forced into the ends of the sheath. In one form, Figs. 14 and 18, a sheath 4 is formed by bending a metal strip into tubular form and welding along overlapping edges, a core 5 being then inserted. Alternatively the metal strip may be wrapped round a core by rolling or drawing, or the sheath may be a plain or butt welded lube. Discs or plugs 7, Fig. 18, are welded to the sheath. An aeroplane incorporating elements formed as above described comprises stub wings 2 formed integrally with the structure of fuselage 1, Fig. 2, and main wing portions 3. Each wing includes three spars a, b, c, Fig. 3, each constituted by booms 8, 9, Fig. 12, connected by vertical struts 13 and diagonal braces 14 secured to the booms and to each other by gussets. The spars are interconnected by upper rib elements 10 and lower rib elements 11 having outwardly turned flanges 18, for attachment of the skin 12 and notched as shown to clear the booms to which they are secured by welded angle gussets. Supplementary booms 19 extend the full length of the wings, Figs. 3 and 4, and are disposed one at each side of spar b and supplementary booms 20 are arranged between booms 19 and spars a and c, these booms extending only part of the span, Fig. 3. Midway between booms 9 of spars a and b and of spars b and c, respectively, are disposed supplementary booms 21 extending outwardly beyond booms 20 but terminating short of the full span. Booms 9, 19, 20, 21 and upper and lower rib elements are interconnected by diagonal braces 22, Fig. 4, in the planes of the ribs. In addition, pairs of diagonal braces 23 are arranged as shown in Fig. 3 between booms 19 and 21 at the mid‐section of the wing. In the root bay of the wing, Fig. 3, booms 20, 21 are connected by pairs of braces 24 and booms 19, 21 by pairs of braces 25, Figs. 3 and 6, the latter being stabilized by struts 26. All connexions are effected by welded gusset plates. The internal structureof thestubwings 2 which is continuous through the fuselage, Fig. 2, is of the same construction as that of the root bays of the main wings and the connexion between the stub and main wings is by angle strips 30, Fig. 7, bent to the wing contour and secured one to the stub and one to the outer wing by welding the inner flange between the wing skin 12 and internal structure, the strips being secured to one another by bolts 32 passing through out‐turned flanges 31 of the strips and the margin of a bulkhead 29. Upper and lower spar booms, longerons, and gussets of each wing part merely abut on the bulkhead 29. The nose and tail portions of the wing comprise rib parts 33, 36, respectively, Fig. 4, secured to front and rear spars at rib attachment points and channel stringers 35, 37, respectively, Fig. 3, to which and to the rib parts skin 12 is spot welded. Wing tip 38 is formed by welding the overlapped edges of a shaped sheet metal shell to the main wing body. The fuselage frame, Fig. 16, 17, incorporates composite wood‐metal members and comprises longerons 39, vertical and transverse struts 40, and diagonal struts 41, secured together by spot welded angle plates 42. The corner angles are reinforced by braces 43 attached to the struts by welded‐on plates 44.