Transportation industries are obliged to address concerns arising from greater emphasis on energy saving and ecologically sustainable products. Engineers, therefore, have a responsibility to deliver innovative solutions that will support environmental preservation and yet meet industries' requirements for greater productivity and minimised operational costs. Aluminium alloys have successfully contributed to meeting the rising demand for lightweight structures. Notable developments in aluminium welding techniques have resolved many welding related problems, although some issues remain to be addressed. The present study attempts to give an overview of the key factors related to the formation of defects in welding methods commonly used with aluminium alloys. First, a concise overview of defects found in friction-stir welding, laser beam welding and arc welding of aluminium alloys is presented. The review is used as a basis for analysis of the relationship between friction-stir welding process parameters and weld defects. Next, the formation and prevention of the main weld defects in laser beam welding, such as porosity and hot cracking, are discussed. Finally, metallurgical aspects influencing weld metal microstructure and contributing to defects are tabulated, as are defect prevention methods, for the most common flaws in arc welding of aluminium alloys.

There is an increased requirement in the automotive, food and medical equipment industries to weld heatsensitive materials, such as thin sheets, coated thin plates, stainless steel, aluminium and mixed joints. Nevertheless, relevant innovations in arc welding are not widely known and seldom used to their maximum potential. In the area of gas metal arc welding welding processes, digitalisation has allowed integration of software into the power source, wire feeder and gas regulation. This paper reviews developments in the arc welding process, particularly the effect of the setup of the welding process parameters on waveform deposition. It is found that good weldability, good mechanical joint properties and acceptable process efficiency can be obtained for thin sheets through advanced power source regulation, especially over short circuiting, controlled polarity and electrode wire motion. The findings presented in this paper are valuable for waveform and deposition prediction. The need is furthermore noted for an algorithm that integrates gas flow parameters and wire motion control, as well as a variable sensor on the tip of the electrode, permitting flexibility of control of the current and the voltage waveform.

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Arc behaviour is a significant factor in all arc welding processes. Understanding of arc types and their inherent properties can help enhance weld prediction and weld quality and reduce welding cost and production cycle time. Advanced welding processes utilize real-time control and prediction, increasing the need for detailed knowledge of arc characteristics and arc applications. This paper analyses the types of welding arcs used in the welding industry, explains corresponding features and characteristics, provides guidance for suitable applications, and presents arc type comparisons, benefits, and weaknesses. The study is based on a review of the literature, and it provides a comprehensive overview of arc phenomena. The results of this work show that in many applications, greater benefit accrues from spray and pulsed arcs than short and globular arc modes. Controlled short arc, heavy deposition rate arc, and controlled spray arc are enhanced arc processes offering significant improvements in efficiency and usability. This review can assist companies in making appropriate choices of arc and welding process for different materials and applications. Furthermore, it can be utilized as a basis for further research.

The welding of dissimilar materials finds a wide variety of applications in the fields of industrial construction and manufacturing, where the characteristic features of the different materials are optimized for the desired application to result in cost effectiveness and value addition. Non-fusion welding methods such as solid state welding and high energy beam welding are more popular for welding dissimilar metal combinations, due to fewer complications, than fusion welding, which melts the base metal and forms brittle intermetallic compounds (IMCs) that may lead to failure. Various factors have to be considered when assessing the feasibility of welding dissimilar metals and producing a sound weld joint. This paper presents a broad classification of the most commonly used welding processes for dissimilar materials, discusses some of the commonly used welding processes with examples of some common material combinations, critical factors for good welding, and practical difficulties arising from the physical and chemical properties of materials. From the findings, it can be inferred that continuous improvement and research is still required in the field of dissimilar metal welding, particularly in the light of increasing demand for tailored material for modern engineering and industrial applications.

Dissimilar welding of aluminium (Al) and copper (Cu) has many applications in the electric power, electronic and piping industries. The weldments in these applications are highly valued for their corrosion resistance, heat and electricity conducting properties. The Al-Cu joints are lighter, cheaper and have conductivity equal to that of copper alloys. Much research has investigated dissimilar welding of Al-Cu by solid-state welding and fusion welding processes with the aim of optimising the properties and strength of such dissimilar joints. The main aim of the study is to critically review the factors influencing the properties of the Al-Cu joint. The study mainly discusses about the effects of intermetallic compounds (IMC) on the properties of Al-Cu joint and their effect while in service. The effects of joining aluminium alloy 1060 with pure copper by laser welding, friction stir welding and brazing have been reviewed and compared. The review shows that the various intermetallic compound formations in the joint have both beneficial and detrimental effects. The characteristics of these intermetallic compounds vary according to the location of the phase formed. Comparison of processes and parameters for welding of Al 1060 with pure Cu shows that the formation of the intermetallic compounds and their effects on the weld properties are mainly influenced by the welding speed, heat input, the thermal properties of the base metals and the filler metal as well as the dilution between the base metal and filler metal.

This work presents a review of the three most efficient non-destructive testing methods. The methods are radiography, eddy current and ultrasonic inspection. These particular techniques were chosen because they are able to cover most of the industrial needs for welding joint inspection. The aim of this work is to present the physical background of operation for the given methods, discuss their benefits, limitations, and typical areas of application, and compare them with each other. In the first part of this work, all three methods and their variations are described in detail with schemes and figures which represent their working principles. It appears that, although all the given methods can detect all types of flaws in welded joints, they have their specific limitations. For example, ultrasonic testing is able to detect defects only in certain directions. The eddy current technique is also sensitive to defect direction, but it can be applied for inspecting conductive materials only. The main flaw of radiography is the resolution: it is not usable for very fine defects. The second part of the work is for comparing the testing methods and for drawing the conclusions. The methods are compared according to the possible materials, defect types and their position, as well as the possible areas of application. This part gives the background for choosing a proper welding joint testing method for certain applications in the welding industry.

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