Modeling of the Off-Axis High Power Diode Laser Cladding Process

Abstract

Off-axis high power diode laser (HPDL) cladding is commonly used for surface quality enhancement such as coating, part repairing, etc. Although some laser cladding models are available in literature, little has been reported on the modeling of powder flow and molten pool for a rectangular beam with side powder injection. In this article, a custom-designed flat nozzle delivers the powder material into a distinct molten pool formed by a HPDL with a rectangular beam. A powder model is first presented to reveal the powder flow behavior below the flat nozzle. Key parameters such as nozzle inclination angle, rectangular beam profile, shielding gas flow rates, and powder feed rate are incorporated so that spatial powder density, powder velocity, and temperature distribution are distinctly investigated. Then in order to describe thermal and fluidic behaviors around the molten pool formed by the rectangular beam, a three-dimensional self-consistent cladding model is developed with the incorporation of the distributed powder properties as input. The level set method is adopted to track the complex free surface evolution. Temperature fields and fluid motion in the molten pool area resulting from the profile of rectangular beam are distinctly revealed. The effect of continuous mass addition is also embedded into the governing equations, making the model more accurate. A HPDL cladding with little dilution is formed and the simulated results agree well with the experiment.

Multiscale Modeling of Transport Phenomena and Dendritic Growth in Laser Cladding Processes

“…The term M(x, y, z) and v p are affected by the nozzle geometry and the parameters of the laser (mode and power level), powder (feeding rate, feeding angle, and particle shape), and shielding/carrier gas (flow rate). Their values are calculated by an independent numerical model, [12] which predicts the powder stream flow inside and outside the nozzle and the laser-particle interaction process by solving a set of governing equations of turbulent gas flow and powder dynamics/thermal behavior. The H term in Eq.…”

“…The model has been validated by actual cladding experiments with different laser-density profiles and powder distributions. [11,12] In contrast, different models have been developed to investigate the microscale dendritic growth and solute redistribution in the molten pool. The Monte Carlo (MC) model has been used to by Yang et al [15] and Koseki et al [16] to predict the grain size and distribution in the molten pool as well as in the heat affect zone, and a good agreement with experimental results was obtained.…”

“…The element activation method has been used in finite-element models, [1,2,5] whereas the volume-of-fluid method [7] and the level-set method [6,[8][9][10][11][12] have been used in finite-volume and/or finite-difference models in which the thermofluid flow has been considered. An improved level-set method was proposed by Wen and Shin [11,12] to capture the evolution of the free surface of clad tracks. Additional source terms have been incorporated into the governing equation set to consider more rigorously the effects of continual additions of mass and energy from the deposited powder.…”

“…Some models have been developed based on a heat conduction equation with the consideration of latent heat of phase transformation, [1][2][3][4][5] whereas other models have included a convection term in the formulation to have a more complete consideration of the underlying physics. [6][7][8][9][10][11][12] The most challenging issue in the modeling of cladding processes is to track the freesurface evolution caused by material deposition. Some models are based on a simplified formulation with a predefined geometry of clad track, [13,14] which can give only qualitative results.…”

Advances in the modeling of laser direct metal deposition

“…Gas flow in the powder stream was taken as turbulent, described by the k-e model as reported in another paper dedicated to this subject. 67 The model was also applied to two overlapping tracks, 68 off-axis deposition 69 and cladding with an additional hard particle phase. 70 The model of Ibarra-medina et al incorporated the same effects but considered an annular nozzle and used the volume of fluid (VOF) method (Fig.…”