Prospects of laser beam welding and friction stir welding processes for aluminum airframe structural applications

Microstructure and failure mechanisms of refill friction stir spot welded 7075-T6 aluminum alloy joints

The influences of rotational and welding speeds on microstructures and mechanical properties of friction stir welded Al5083 and commercially pure copper sheets lap joints

Defect features and mechanical properties of friction stir lap welded dissimilar AA2024–AA7075 aluminum alloy sheets

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.

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Investigation of weld defects in friction-stir welding and fusion welding of aluminium alloys

Effect of welding parameters on microstructure and mechanical properties of friction stir spot welded 5052 aluminum alloy

In the present study, AA6061-T4 T-joints were successfully fabricated by friction stir welding (FSW) in three different combination ways of skins and stringers. Distributions and formation mechanisms of tunnel defects, kissing bond defects, original joint line with severe plastic deformation (OJLwSPD) defects, and zigzag line defects in T-joints were investigated by macro- and micro-observations. Influences of defects distributions and welding parameters on the tensile behaviors of T-joints were examined. To a better understanding of failure behaviors of T-joints, fracture locations and fracture surfaces of tensile samples were also investigated.

Characteristics of defects and tensile behaviors on friction stir welded AA6061-T4 T-joints

Microstructures and fatigue properties of friction stir lap welds in aluminum alloy AA6061-T6

Influences of joint geometry on defects and mechanical properties of friction stir welded AA6061-T4 T-joints

Friction stir welding (FSW) of T-joints with 3 mm thickness for AA6061-T4 sheets has been performed, and the influences of process parameters on the microstructures, defects, hardness profiles, and tensile strength were discussed specifically. It is found that the macrostructures and microstructures are similar in different process parameters, and the microstructure features in the skin welds have the same patterns as that of butt-joints. The unique microstructures of T-joints are the two fillet zones. Two lower hardness zones in the skin and one lower hardness zone in the stringer are found. Additionally, the tensile properties of T-welded joints are examined along the skin and the stringer plane directions. Results show that the tensile strength is in the range of 170-180 MPa for all the specimens along the skin direction, and the specimens fail in the heat affected zone (HAZ). In the stringer direction, the larger tunnel defects (DA) (the DA is greater than 0.1 mm2) would reduce the ultimate tensile strength of the T-joints and cause the joints to fracture at the bonding interface. The smaller tunnel defects (the DA is less than 0.015 mm2) and the zigzag lines have no pronounced effect on the failed location. In the stringer direction, tensile efficiencies of T-joints could be 83% of the base material (BM) when ω/v = 1541/218 r/mm is applied.

Guang Zhou

Papers

Effect of welding parameters on microstructure and mechanical properties of friction stir spot welded 5052 aluminum alloy

Characteristics of defects and tensile behaviors on friction stir welded AA6061-T4 T-joints

Microstructures and fatigue properties of friction stir lap welds in aluminum alloy AA6061-T6

Influences of joint geometry on defects and mechanical properties of friction stir welded AA6061-T4 T-joints

Study on the Microstructures and Tensile Behaviors of Friction Stir Welded T-joints for AA6061-T4 Alloys