Controlling fusion zone shape and peak temperature produced by laser or electron beam

The fusion zone shape and peak temperature in melting or welding encountered in packaging and manufacturing technologies can be generally correlated as a function of four independent working parameters. They are dimensionless beam power, Marangoni, Prandtl and modified Peclet numbers. Dimensionless beam power includes the beam power and beam radius, Marangoni number represents the driving force, namely, surface-tension gradient coefficient and viscosity, Prandtl number stands for the ratio between momentum and thermal diffusivities, and the modified Peclet number includes scanning speed, specific heat, solid-to-liquid thermal conductivity ratio, difference in melting and ambient temperatures and latent heat. Determination of the fusion zone shape and peak temperature is crucial due to its close relationship with the strength and properties of the packaging and manufacturing products. The correlated results agree with numerical data, and available experimental data. This unified work can thus be successfully used to control the fusion zone shape and peak temperature prior to welding and melting.