Coupling Model and Numerical Computation Method of Keyhole and Weld Pool

This chapter introduces a self-consistent model of coupled keyhole and weld pool dynamics and its numerical implementation for keyhole mode laser welding. A self-consistent heat source model dependent on the transient three-dimensional keyhole profiles is presented by using the ray tracing algorithm. Governing equations for three-dimensional transient heat transfer and fluid flow of weld pool and keyhole free surface tracking are given in detail. The discontinuous boundary conditions of thermocapillary force, surface tension and recoil pressure on the interface between keyhole and weld pool are deduced based on incompressible viscous flow assumptions. Numerical implementations of this self-consistent model are also introduced.