A mesoscale solidification simulation of fusion welding in aluminum–magnesium–silicon alloys

Abstract

A 3-D granular model has been developed to simulate solidification during fusion welding of Al alloys. The model simulates the gradual development of the weld mushy zone composed of both continuous liquid films and solidifying grains by coupling thermal fields based on the Rosenthal equation, a modified Voronoi tessellation to provide grain structure at the mesoscale, and the evolution of solid fraction within a grain based on the Scheil equation. The shape and geometry of the columnar and equiaxed grains within the weld pool has been characterized from experiments, and therefore the model can be used to link the solidification behaviour of individual grains to the macroscopic properties of the weld. The gradual formation of microscale liquid channels lying along the grain boundaries within the mushy zone is investigated and the role of welding parameters, including amperage and welding speed, on transitions in the semisolid microstructure is explored. The study reveals that the ability of the microscale liquid channels to feed molten metal into the solidifying areas is not uniform through the weld, and is strongly affected by grain size since smaller grains hinder the feeding ability of the mushy zone.

Three-dimensional cellular automaton-finite element modeling of solidification grain structures for arc-welding processes

“…Control is generally achieved by adjustment of the wire composition and tentative to form an equiaxed zone. Studies have been reported to model the grain structure developed in welding processing together with prediction of the internal pressure [2] or the liquid feeding ability at intergranular liquid channels [3]. The mechanical properties of the joints are also linked to the anisotropy of the grain structure developed in the weld bead, especially in case of multiples passes processes when large grains develop [4].…”

3-D multi-scale modeling of deformation within the weld mushy zone

“…The semisolid region of a weld, called the mushy zone, consists of grains forming a solid body within a network of micro liquid channels covering each grain [1][2][3]. At high solid fraction, the micro liquid channels may deform due to the solidification shrinkage, if a lack of feeding is present, and consequently induce local tensile deformation [3][4][5][6].…”

A Multi-scale Thermomechanical-Solidification Model to Simulate the Transient Force Field Deforming an Aluminum 6061 Semisolid Weld

“…The width and thickness of the base metal are assumed to be 50 mm and 3 mm, and the simulated weld length is set at 20 mm. The shape of the material removed representing the weld pool is given by the welding procedure, and was determined experimentally [18]. As shown in Fig.…”

“…The Solidification module uses the model of Zareie Rajani et al [18] to simulate solidification of the weld pool at the meso-scale. This model is composed of both columnar and equiaxed solid grains and also a network of micro liquid channels spread between each grain; the fully solid microstructure is generated from a series of Voronoi tessellations performed on different regions in space.…”

“…Zhong et al [16] and Bordreuil et al [17] have used cellular automaton (CA) methods to reconstruct in both 2-D and 3-D the microstructure of the weld directly after solidification. Zareie Rajani et al [18,19] used a multi-scale model based on a method proposed by Mathier [20] to reconstruct in 3-D the evolving semisolid composed of solidifying grains and micro liquid channels. Unlike the first step, the second step, i.e.…”