Numerical Modeling of Transport Phenomena and Dendritic Growth in Laser Spot Conduction Welding of 304 Stainless Steel

Abstract

A multiscale model is developed to investigate the heat/mass transport and dendrite growth in laser spot conduction welding. A macroscale transient model of heat transport and fluid flow is built to study the evolution of temperature and velocity field of the molten pool. The molten pool shape is calculated and matches well with the experimental result. On the microscale level, the dendritic grvwth of 304 stainless steel is simulated by a novel model that has coupled the cellular automata (CA) and phase field (PF) methods. The epitaxial growth is accurately identified by defining both the gr-ain density and dendrite arm density at the fusion line. By applying the macroscale thermal history onto the microscale calculation domain, the microstructure evolution of the entire molten pool is simulated. The predicted micr-ostructure achieves a good quantitative agreement with the experimental results.

The influence of surfactants on thermocapillary flow instabilities in low Prandtl melting pools

“…This enhanced heat and momentum transport is in agreement with ad-hoc modifications necessary to match experimental results in previously published numerical studies of industrial processes involving thermocapillary flows in liquid low Prandtl number pools, where the flow has been assumed to be laminar. 24, [47][48][49][50][51][52] It is noteworthy that the self-sustained oscillations arise even without taking into account complex interactions such as a deformable liquid-gas interface, temperature dependent material properties, non-uniform surfactant concentrations or additional, competing forces such as buoyancy.…”

Mathematical modeling of the electron-beam wire deposition additive manufacturing by the smoothed particle hydrodynamics method

“…7) a two-phase zone of a melt is set by a liquidussolidus transition under melting temperature; 8) an effect of latent heat during cooling is neglected; 9) capillary forces are not taken into account; 10) an effect on the motion of a melt of electric and magnetic fields generated by an electron flow is not considered. Table 2 shows the Grade 2 Titanium's (Tang et al 2014;Fox and Beuth 2013) and the 308LSi Steel's (Wang et al 2011;Tan et al 2012;Pang et al 2016) physical characteristics necessary for numerical modeling by the above smoothed particle method.…”

A Modified Cellular Automaton Model for the Quantitative Prediction of Equiaxed and Columnar Dendritic Growth

“…To deal with the problem, the decentered square/octahedron algorithm originally proposed by Rappaz et al, was later modified by Wang et al [7] , through coupling the finite difference model to solve the solute diffusion equations. The algorithm eliminated the effect of grid anisotropy and was adopted by many workers to describe the dendritic growth with arbitrary preferential orientation [3,8,25,26] . On the basis of this technique, the solutal interaction within an advancing columnar dendritic network and columnar-to-equiaxed transition of Al-Cu alloys were investigated by Dong and Lee [13] , and the stray grain formation mechanism in the platform region of turbine blades was revealed by Yang et al [27] .…”