Surface patterns of bead defects such as humping, gouged and rippling after solidification during laser and electron processing and different welding processes are systematically and quantitatively studied in this project. These defects usually accompanying with porosity, undercut, segregation, stress concentration, etc. seriously reduce the properties and strength of the surface heat treatment and weld joint. In order to improve quality, assure mass production and repeatability and reduce costs, it is necessary to understand their mechanisms. Although the defects have been extensively studied in the past, systematical, penetrative and quantitative understanding of their formation from thermal, physics, and pattern selection viewpoints are limited.The study include thermocapillary force, evaporation, and phase changes between solid-liquid and liquid-gas phases by introducing energy equation and interfacial and kinematic boundary conditions to simulate realistic processes.

This project is to explore the manufacturing and processing of laser or electron beam, formed on the surface morphology after curing and processing parts, such as surfacefilled, depression, or the formation of ripples; These reactions will directly affect the surface heat treatment and welding quality of thefinished product This study to consider the mass, momentum and energy equations, the introduction of theinterface and boundary conditions to simulate the real process In order to promote quality stability, and a large amount of production capacity and reduce costs, we must understand the institutions of the reaction In this thesis, the phase field method (Phase-field method) (Two-phase flow) two-phase flow simulation of metal surface by a concentrated source of heat melt the transient heat flow behavior