Renkun Dai

Melting widely exists in various industrial applications and melting control through an extra magnetic field is a promising subject. Recent studies mainly focus on the suppression effect of the magnetic induced Lorentz force. However, the influence of magnetic force is less investigated. The present study concentrates on investigating the impact of magnetic force, along with gravity, on the melting process. The magnetic quadrupole field is used to generate magnetic force and the temperature distribution, velocity field and melting front are obtained through lattice Boltzmann method. Results indicate that the magnetic force can enhance the flow and heat transfer during the melting process and it has the potential to be used to control the process. Besides, the gravity accelerates the melting process when the dimensionless magnetic force parameter is less than 20, whereas its effect can be ignored when the parameter is larger than 20.

The melt pool is the general process of the laser additive manufacturing process. An in-depth understanding of the evolution of the melt pool will facilitate obtaining an optimum mechanical performance. In this paper, a novel 2D transient model is presented, which considers most physical phenomena taking place in the laser melt process and incorporates a coupled multiphase capture method. This model is validated by comparing it to Han’s research. Then an investigation on the transient thermal dynamic in the melt pool including quenching time is carried out, and the effects of evaporation and alternative material properties on the evolution of the melt pool are discussed. The results show that the deformation of the free surface and the temperature in the workpiece both increase with energy input. After quenching, the temperature in the workpiece decreases sharply and the melt pool also shrinks. The evaporation effect is vigorous in the center of the melt pool and negligible in the periphery. The material properties have significant influence on the evolution process because the convection and diffusion in the melt pool are directly dominated by them.