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Laser Heating of a Moving Slab: Influence of Duty Cycle and Irradiated Spot Diameter on Temperature Field
S.Z. Shuja, B.S. Yilbas and H. Ali

Laser consecutive pulse heating of a moving thin slab is considered and temperature field in the irradiated region is predicted. The influence of the duty cycle and the irradiated spot diameter on temperature rise is examined in details. A numerical model incorporating the final element method (FEM) model is introduced to predict temperature filed inside the irradiated substrate material. It is found that the effect of duty cycle on temperature rise is significant; in which case, increasing duty cycle results in attainment of high temperature at the irradiated surface. Increasing irradiated spot diameter enhances temperature rise at the irradiated spot centre. In this case, heat diffusion is suppressed by the attainment of low temperature gradient in the radial direction and the internal energy gain by the substrate material due to absorption of the incident radiation enhances temperature rise at the surface. Local melting occurs for low duty cycles, which in turn results in wavy appearance of the melted region along the laser scanning direction at the surface. Increasing duty cycle and irradiated spot diameter enhances the melt width size at the surface. The consecutive laser pulses gives rise to temperature rippling at the irradiated surface, which is more pronounced for low duty cycles and small irradiated spot diameter.

Keywords: Laser heating, temperatue, duty cycle, diameter, numerical model, finite element method (FEM), consecutive pulses, phase change, moving slab

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