Abstract
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.
Highlights
Aluminium alloys have been one of the primary candidates for material selection in many industries, including the commercial and military aircraft and marine sectors, for more than 80 years, mainly due to their well-known mechanical behaviour, design ease, manufacturability and the existence of established inspection techniques (Dursun and Soutis 2013)
In the second part of the paper, we focus on laser beam welds and investigate defect mechanisms in laser beam welding of aluminium
Longitudinal and transverse distortion is minimised in the frictionstir welding (FSW) process due to the lower peak temperature in FSW compared to arc welding processes
Summary
Aluminium alloys have been one of the primary candidates for material selection in many industries, including the commercial and military aircraft and marine sectors, for more than 80 years, mainly due to their well-known mechanical behaviour, design ease, manufacturability and the existence of established inspection techniques (Dursun and Soutis 2013). Heat generated for joining can cause significant changes in material microstructure, thereby compromising the mechanical property of the base metal and causing weld distortion. Characteristics of friction-stir welding Friction-stir welding (FSW) has been considered as the most significant development in metal joining of the past decade It is regarded as a green technology because of its energy efficiency, environmentally friendly nature and versatility. Friction-stir welds have a somewhat different microstructure to welds from fusion welding processes, because the maximum peak temperature in the heat-affected zone is significantly less than the solidus temperature and the heat source is rather diffused (Nandan et al 2008). Some aluminium alloys that are either not weldable or difficult to weld due to problems of brittle phase formation and cracking are weldable by friction stir welding as it is a solid-state process. Longitudinal and transverse distortion is minimised in the FSW process due to the lower peak temperature in FSW compared to arc welding processes
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