Modelling the effects of laser beam geometry on laser surface heating of metallic materials

Optimisation of different laser processes requires control over the fundamental parameters of laser processing i.e. heating / cooling rate and thermal gradient. Different processes have different requirement of heating/cooling rate and thermal gradient. If we can control these parameters we can optimise laser processing of materials. Knowing these parameters and relevant metallurgical information we can predict the microstructure and hence control the material properties. The effect of laser beam geometry on laser processing of materials has received very little attention. Laser material processing have been carried out in the past using circular or rectangular beams. This paper presents an investigation of the effects of different beam geometries including circular, rectangular and triangular shapes. Finite element modelling technique has been used to simulate the transient effects of a moving beam for laser surface heating of metals. The temperature distributions, cooling rates and thermal gradients have been calculated. Some of the results have been compared with experimental data.