Dispersoid-free zones in the heat-affected zone of aluminum alloy welds

Abstract

The local microstructure in the heat-affected zone 1 (HAZ1) of a laser beam-welded Al-Mg-Si-Cu aluminum alloy is investigated closely. Dispersoid-free zones (DFZs), where the dispersoids of the base material (BM) are dissolved, are found in the vicinity of the fusion line (FL). They are not uniformly surrounding a grain, but oriented toward the FL. Their width can be as large as 10 m. Detailed analysis has revealed a decreased silicon concentration as well as a decreased hardness of the oriented dispersoid-free zones (ODFZs). Two mechanisms for the formation of this welding metallurgical feature are discussed.

Tensile fracture behavior in CO2 laser beam welds of 7075-T6 aluminum alloy

“…So the solute segregation commonly takes place in the fusion zone of aluminum alloy welds. In such fusion zones, Cu, Mg and Zn segregated along cellular boundaries, which resulted in the formation of low-melting-point eutectic products [14,24]. For example, Cu contents in the dendritic core regions were much lower than the normal content.…”

Microstructure controlled bending response in AA6016 Al alloys

“…They found that by promoting more dispersed slip, or by grain refinement the intergranular fracture mode can be replaced by the conventional ductile rupture in which void formation and shear banding became more pronounced than grain boundary decohesion. Practically, several possible sources of intergranular fracture can be delineated: (i) reduction in the local cohesive stress due to segregation or presence of grain boundary particles, (ii) initiation, growth and coalescence of micro-voids, formed on the grain boundary particles, (iii) localization of the deformation in precipitation free zones (PFZs) adjacent to the grain boundaries, (iv) promotion of coarse slip in the bulk of the grains, and (v) coarsening of the grain size [5,[7][8][9].…”

Laser-Machined Microchannel Effect on Microstructure and Oxide Formation of an Ultrasonically Processed Aluminum Alloy

“…[29] suggesting that the recast layer consists of oxidized material and resolidified melt. [39] showed that this zone is softer and experiences a reduction in hardness. [29] stated that an oxide layer is possibly formed on the recast layer.…”